The History of Diamonds in Engagement Rings

Jack Ogden FGA takes a look at the history of diamonds being used in engagement rings. You might be a little surprised at how far the custom dates back...

Here is a question for you. Read this sentence about engagement rings: “As for the engagement ring, modern fashion prescribes a diamond solitaire, which may range in price from two hundred and fifty to two thousand dollars.” When do you estimate that was written? Before or after World War II? 

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Diving into the World of New Zealand Paua Shells

Paua shells are the archetypal New Zealand gem - possibly even better known than its nephrite jade, known as 'greenstone', or Kauri copal, the fossilised resin or sap of the Kauri Tree. Here, Maggie Campbell Pedersen FGA looks to the ocean to learn more about paua shell, how it is farmed and how it is used in jewellery design. 

What are paua?

Paua belong to the large family of molluscs called Haliotidae, of which there are well over 100 species worldwide. Six are found in New Zealand, although only three are common. The most famous and exclusive to New Zealand is the Haliotis iris, known for the beautiful, vibrant colours of the inside surface of the shells. These colours range from striking blues through to aquamarines to greens, with tints of purple and gold. They are influenced by what the animal eats and therefore vary slightly from region to region.

Haliotis are marine gastropods. They carry one shell, and have one large, very muscular foot with which they attach themselves to rocky surfaces (in the case of H. iris the foot has a black outer skin). The name 'Haliotis' derives from the Greek, meaning 'sea ear', and along one side of the shells are small holes for expelling water in the aeration of the gills. The shell is made up of three layers: a very thin outer layer of conchiolin (a tough, insoluble protein secreted by molluscs, forming the organic matrix of the shell), under which is a chalky-looking rough material and beneath that is the coloured nacre (mother-of-pearl).

In common with other molluscs, the layers of calcium carbonate (in the form of calcite and aragonite) and conchiolin that form their shells, are laid down by the molluscs' soft bodies. Haliotis, however, lay down the inner layer of aragonite crystals and conchiolin in a slightly haphazard way, stopping altogether if the water temperature does not suit them. This results in areas where the conchiolin becomes very visible, giving an effect of wavy lines of organic material interspersed with beautifully coloured nacre.


A captive-bred, live mollusc ready to be harvested at a farm in Thailand

Where can paua be found?

Pauas live around the rocky coasts of New Zealand and are found at or below the level of the lowest spring tide, that is, at a depth of between one and 12 metres. Much of the paua used for gem purposes are wild-caught, under licence and to extremely strict quota. They can only be fished by free diving - no scuba is permitted - and only a certain number may be fished at any one time, all of which helps to keep the stocks of paua healthy. Furthermore, they may not be fished unless they measure a minimum of 125 mm at the longest part of the shell, which they usually reach at the age of about six years.

When did paua aquafarming start?

Paua aquaculture started in New Zealand in the 1980s. The captive-bred molluscs can be harvested when they are smaller - at about three years old. They are largely used for food, as the shells are not of quite such a vibrant colour. The outer, chalky surface of farmed paua is also pale blue (as opposed to the pale brown of wild paua), due to their feed. The soft bodies of farmed paua are slightly paler, which is considered more attractive as food - indeed the very black surface of the wild paua's flesh is usually removed before the meat is consumed.

The flesh of the paua is very rich in protein and has been a staple diet of the Maoris, who also used some of the shells in their carvings, almost always to depict eyes. In the large, wooden carvings that adorned Maori ceremonial houses and canoes whole shells were used, and were attached so that the inner, nacreous surface was visible (see below).

Paua shells used as eyes in a traditional Maori carving

How is paua used in jewellery?

The paua shell trade is unusual in that it is found at both ends of the market. It is well known in the form of colourful, whole polished shells, or inexpensive jewellery and trinkets, which are sold as souvenirs in museum shops and other such places. In jewellers' shops can be found the expensive paua shell items, set in precious metals and with gemstones (see below). At the inexpensive end of the market a little paua shell can go a long way when embedded in moulded clear plastic with a black backing, and is sold in great quantities to the tourist trade. It is made up into various designs, often depicting something specific to New Zealand such as a kiwi bird.


A paua shell necklace by Catherine Best Ltd.

When paua shells are sold whole, the outer, chalky-looking surface is removed to reveal the colourful, nacreous surface beneath, and it takes an expert only about 10 minutes to polish a raw shell on a diamond wheel (see main image). The typical pattern of the nacre with its dark, wavy lines of conchiolin is very attractive, and this is revealed when the outer layers of shell are removed. However, the inside surface of the nacre has a much smoother, almost liquid transition of colours, far fewer lines of conchiolin, and is subsequently considered the better material.

It is from there that the best pieces are taken to make jewellery, and is of course the area in which hemispheres of material are placed to produce blister pearls.

How are paua pearls cultured?

These blister pearls, also known as 'blue pearls', first came onto the market around the turn of the millennium.

These round blister pearls, usually referred to as mabés, are mostly produced from wild-caught paua, which are nucleated and treated in much the same way as the oysters in the culture of marine pearls, that is, by suspending them in baskets from lines in areas of clean water and tending them regularly.

The process of inserting the nucleus must be undertaken with utmost care as the smallest incision in the mantle can result in the death of the mollusc - they have no blood-clotting agent and therefore would bleed to death.

Natural paua pearls do exist, but they are always concretions produced by the animal outside the mantle and are inevitably very oddly shaped (see below). The success rate of the pearl production is not high. Only 10% will produce a marketable blister pearl covered with nacre, and only 2% will produce a smooth one of top quality and colour.


A natural paua pearl

Not only must the animals not be injured during the nucleation process, when the mantle is carefully lifted to insert the hemispherical bead underneath, they must then be kept in a stress-free environment for the two to three years it takes to cover the nucleus with nacre and produce a 'blue pearl'.

As with all organics, science alone cannot ensure success. We also have to rely on the assistance and co-operation of a living creature. ■

The full version of this article originally appeared in Gems&Jewellery July/August 2016 / Volume 25 / No. 4 pp. 10-12

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

All photos by Maggie Campbell Pedersen, except where otherwise stated


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


Additional Info

Read more...

A Quick Guide to the Crown Jewels at the Tower of London

Andrew Fellows FGA DGA takes a look some of the myths and legends associated with one of the world’s most famous gem collections, the Crown Jewels of the United Kingdom.

Foundations were laid for the Tower of London - where the famous Crown Jewels are housed - as early as 1066 by William the Conqueror. Successive monarchs then added to and reinforced the Tower, until, by the late thirteenth century, the general layout seen today was established. The Crown Jewels, the only working collection in Europe, is comprised of over 141 objects, which have been stored securely within the Tower for hundreds of years. It is these that attract hordes of tourists each year.

However, whilst the collection is worth seeing simply for the sheer beauty of the pieces, it is also worth seeing to learn about the captivating stories and histories behind some of the gems.

The Crown Jewels: The Imperial State Crown

The Imperial State Crown - possibly the most well-known individual piece of regalia in the collection - is worn by the monarch at the end of his or her coronation ceremony, and is also used for the State Opening of Parliament. The Crown is such an important piece that it even has its own coach for these important occasions - one that is every bit as ornate as the crown itself. Weighing in at an impressive 3.17 kg, it can only be worn for short periods.

One story says that when George IV was crowned in 1821, he developed a toothache that he blamed on the weight of the crown! The crown contains some of the most important jewels in the Royal Collection, many of which also have the most interesting stories attached to them.

The Crown Jewels: Black Prince's Ruby

One story that most gemmologists are familiar with is that of the Black Prince's Ruby. This is simultaneously one of the most beautiful and most sinister stones… and one which is also completely misnamed. Although referred to as ruby, this is actually a very large gem-quality red spinel, presented to Edward of Woodstock, a fourteenth century Prince of Wales, Duke of Cornwall, and Prince of Aquitaine, referred to more often as ‘The Black Prince’.

The Imperial State Crown. Copyright Cyril Davenport. Tower of London
The Imperial State Crown. Copyright Cyril Davenport

The gem, which sits in the cross pattée above the Cullinan II at the front of the crown, has a very dark and bloody history. It was first recorded in the fourteenth century as being owned by a Moorish Prince, Abu Said, who attempted to surrender to the conquering forces of Pedro the Cruel. Abu Said was ambushed under a flag of truce and executed with this large spinel being taken from his corpse.

This was just the start of the trail of blood, as Pedro himself broke several contracts, before presenting the stone to Prince Edward as a down payment for military assistance. The remainder of the payment was supposed to consist of treasure and jewels, but was never delivered, and eventually Pedro himself was ambushed and stabbed to death by his half-brother.

Read more: Last chance to see the record-breaking Foxfire Diamond at the Smithsonian

The stone was later worn in the battle helmet of Henry V when he went into the Battle of Agincourt in 1415, and allegedly saved his life when he received a blow to the head from an axe - one which destroyed the helmet, but didn't kill Henry. The 'ruby' was recovered from the shattered helmet and remained with Henry V until his death.

The same unfortunately cannot be said of Richard III, who also wore the 'ruby' in his battle helmet when he fought at the Battle of Bosworth Field in 1485. Presumably, Richard thought it would protect him and bring him luck, but sadly he was mistaken and died on the battlefield. This same ruby was later used in the crowns of Henry VI, Edward IV and Henry VIII (who wore it in a collar), before being sold by Charles I. It was returned to the monarchy for the crown of Charles II, and was subsequently used for the coronation of George IV.

The Crown Jewels: St Edward's Sapphire

Also in the Imperial State Crown is a sapphire, set in the cross on top of the Crown. Legend has it that this sapphire once resided in the coronation ring of Edward the Confessor, and that one evening he was passing through Westminster when he happened upon a beggar. Having already given away all the money he had on him, he gave the ring to the beggar and thought nothing further of it.

Read more: The history of diamonds in engagement rings

Years later two Englishmen were on a pilgrimage to the Holy Land and, in the middle of a violent storm, saw an old man approaching them. When the old man heard that the two men were English, and that Edward was still King, the old man offered them shelter for the night. When they departed the next morning, the old man revealed himself to be John the Evangelist, and told them that years ago King Edward had given him a ring, which he still had, and gave it to them to return to the King, with a message that he, John, would see the King in Paradise as a reward for his kindness in six months' time.

When the two men returned to England, they gave both the ring and the message to King Edward, who immediately prepared for his death. The King died six months later, to be buried with the ring on his finger. Stranger still is the fact that when the tomb was reopened in the twelfth century, the ring was found on a perfectly preserved corpse.

Tower of London at night. Copyright Kjetil Bjørnsrud. Tower of London
Tower of London at night. Copyright Kjetil Bjørnsrud

Whilst some of these stories are merely legend and may or may not be true, what is known as fact is that the Crown Jewels contain some of the best known and largest diamonds in the world, the most famous of which are probably the Koh-i-Noor and the Cullinan.

The Crown Jewels: Cullinan Diamond

The Cullinan was found at the Premier Mine in South Africa, on the afternoon of 26 January 1905, by the mine superintendent, Captain Frederick Wells. Initially he doubted it was a diamond as it weighed 3106 ct and measured 3 7/8 × 2 1/4 × 2 5/8 inches, well over twice the size of any other diamond found to that date.

This was sold to the Transvaal government for £150,000, and two years later the still uncut diamond was presented to King Edward VII on his 66th birthday. Cutting of the stone was a job given to I. J. Asscher and Company, of Amsterdam, who had some experience of cutting large diamonds, although nothing on this scale or value. After three months of consideration, the Cullinan was ready to be cut.

In those days the only way to divide a diamond was by cleaving it - effectively 'hitting' the stone in precise directions to cause the diamond to part along weaker directions, but this had to be done carefully, in order to avoid shattering it. Careful cleaving resulted in nine major 'pieces', and 96 offcuts. Once the whole cutting process was completed, a total of 1063 ct remained.

Read more: Harrods unearths 228.31 ct diamond from its vaults for private sale

The nine major stones, named Cullinan I to Cullinan IX, all reside in the Royal Collection. The majority are set in such a way as to be interchangeable into other pieces of jewellery. Cullinan I, also known as the Star of Africa, is in the Royal Sceptre, and weighs just over 503 ct, making it the largest colourless pearcut diamond in the world.

The Cullinan II (the 'Lesser Star of Africa'), is the largest cushioncut diamond in the world, weighing 317 ct, and is set into the front of the Imperial State Crown. It also has two platinum loops on its setting, so that it can be removed and worn alone, as a brooch or pendant, or with the Cullinan I accompanying it.

The Crown Jewels: Koh-i-Noor Diamond

A second notable diamond exists in the Queen Mother's Crown, this being the Koh-i-Noor, which translates as 'Mountain of Light'. This impressive diamond currently weighs 105.6 ct, having been recut from its original 186 ct for Queen Victoria in 1852.

There is a legend that this stone will bring good luck to any woman who wears it, but a curse to any man! It is said that in 1739 Nadir Shah of Persia conquered the Mogul region, but could find no sign of this rare and fabled diamond, said to be held by the rulers, until one member of the royal court told him of the stone's location. Shah then threw a celebration, and offered to exchange turbans with the conquered leaders as a show of everlasting friendship, knowing that this was the hiding place of the Koh-i-Noor.

The diamond changed hands many times over the coming decades, until in 1850, the Koh-i-Noor finally found its way to England and to Queen Victoria, where it has remained ever since.

Whilst the Crown Jewels are a wonderful piece of English history, they are also shrouded in legend, and are more than just adornments. There are a multitude of stories and histories, all waiting for visitors to uncover. Whether you appreciate them from a gemmological or historical perspective, or simply want to see jewels that most of us will never afford, the Crown Jewels are the perfect way to spend a day in London. ■ 

This article originally appeared in Gems&Jewellery Sept/Oct 2016 / Volume 25 / No. 5 pp. 14-15

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover image the nine major uncut stones split from the rough Cullinan diamond in order of size (largest to smallest).


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


Additional Info

Read more...

Jewellery History From Elizabeth I to Elizabeth Taylor with John Benjamin

John Benjamin FGA DGA,  jewellery consultant, contributor to BBC’s Antiques Roadshow, author and historian, presented the January Gem Central at Ely Place. Angharad Kolator Baldwin reports on his fascinating lecture…

Starting his career at Cameo Corner, a jewellers previously found in Bloomsbury, John Benjamin successfully passed the Gemmology Diploma and Diamond Diploma courses at Gem-A, before joining Phillips Fine Art Auctioneers as a cataloguer and valuer. After becoming the International Director of Jewellery at Philips, he left to establish his own company, John C Benjamin Limited, an independent jewellery consultancy.

Read more: Gem-A Student Celebrates Southend Success at Houses of Parliament

John’s mission is to "inculcate people with knowledge about antique jewellery" and his talk A History of Jewellery from Elizabeth I to Elizabeth Taylor presented at Gem Central on 17 January, was certainly a splendid opportunity to bask in his extensive knowledge.

The talk began in the sixteenth century and took the audience on a journey through the centuries, showcasing examples of beautiful jewellery in paintings and photographs, demonstrating the widespread fascination the public have with pearls, diamonds and other precious stones.

Gems in the sixteenth century were believed to have prophylactic properties. Evidence has been found that suggests pearls used to be powdered and drunk as a cordial to protect against disease, while garnets were worn against the skin and said to prevent the individual from having nightmares. Similarly smallpox scars were believed to be cleansed with sapphires and peridot was believed to promote love making. Although there have been a few changes in daily practices, gemmologists today still learn the birthstones for each month and gemstones remain associated with mystical and healing properties.

Social change is also reflected in jewellery trends. The obsession at the turn of the sixteenth century with death, when people were acutely aware they were unlikely to survive over 30, and wanted to immortalise their nearest and dearest saw the fashion for Memento Mori (remember you must die) jewels. The emergence of imitation gemstones in the nineteenth century when the rate of crime was rising and rather than risk losing precious jewellery in robberies, it was better to invest in paste and keep the real items in a safe deposit box.

17th Century Memento Mori Slide. Photo supplied by John Benjamin.
An English early to mid seventeenth century gold enamel and hair Memento Mori slide exhibiting the grim symbolism of death common at this time. Image courtesy of John Benjamin

The audience were show a seventeenth century Dutch painting detailing a women’s jewellery box. Containing a diamond necklace and a string of pearls, the jewellery was not dissimilar to what you would find in a jewellery box today. John made the point that nothing fundamentally changes in people’s jewellery choices. Although Antwerp may have revolutionised diamond cutting, and the location of the most prolific diamond mines may have changed, our hunger to adorn ourselves to symbolise wealth and power remains.

"Jewellery follows the money", said John, whether it is the Monarch or the most popular celebrity. For centuries we have ogled the gems adorning powerful and wealthy people and sought to copy the taste of the rich and powerful, in an attempt to emulate their success.

Rose Brooch. Image courtesy of John Benjamin
An elegant early Victorian pave diamond set rose brooch, the principal flowerhead mounted en tremblant to scintillate when worn. Image courtesy of John Benjamin

Despite two fascinating hours, it's clear that John's Gem Central discussion barely touched the surface of his extensive knowledge of antique jewellery. As he moved around the room, the audience holding on to his every word, it was apparent that we were privy to a rare insight into the antique world of jewellery. He told us the story behind pieces, the trends of the past, and what this can tell us about the future.

Read more: Gem Central with Marcus McCallum FGA

There is "a social backdrop to jewellery trends", he informed us. Through understanding what was happening at a particular point in history, we can better understand the fashion.

When asked what he thought the jewellery of tomorrow would be…he replied ethnic jewellery. As society becomes more informed and conscientious, the public are looking for materials from sustainable sources, with a story attached. But as much now as in the past, this choice is affected by those with high status.

The audience were taken on an insightful journey through the progression of jewellery design, from Elizabeth I to Elizabeth Taylor, and had a look at the evolution of jewellery in the twentieth century. John visited many themes including Renaissance pearls, enamel, The Cheapside Hoard, mourning jewellery, the age of the faceted stone, Neo Classicism, Victorian sentiment, naturalism, souvenir jewels and the age of mass production. The broad range of topics discussed meant there was something new for everyone present.

Robert Webster Gem Central with John Benjamin
The Robert Webster Room at Gem-A HQ was packed with an eager audience for John Benjamin's talk.

Hosted once a month at Gem-A headquarters at Ely Place London, Gem Central evenings are a unique opportunity to learn from experts and meet fellow gemmology enthusiasts. Free for Gem-A members and students, or just £10 for non-members. ■

Interested in finding out more? Visit Gemmological Instruments, where you can purchase John’s book, Starting to Collect Antique Jewellery instore or by contacting instruments@gem-a.com.

Interested in attending a Gem Central event? For more information about our upcoming Gem Central events visit the Gem Central page or email events@gem-a.com.

Cover image a sixteenth century Spanish enamelled gold devotional Reliquary Pendant fashioned as a Ram, the fleece studded with pearls. Image courtesy of John Benjamin. 


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

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Explore the Historic Significance and Mythology of Amethyst

Amethyst has been worn for its lovely purple colour and mystical properties for thousands of years. From the Ancient Romans to the present day, Julia Griffith FGA DGA EG explores how this beautiful variety of quartz has stood the test of time. 

As it is the February birthstone, amethyst has always been linked to love and romance. However, throughout history the gemstone has also been connected to luck, good fortune and general positivity. The anonymous poem below sums it up nicely:

The February-born shall find
Sincerity and peace of mind,
Freedom from passion and from care,
If they, the amethyst will wear.
Let her an amethyst but cherish well,
And strife and care can never her dwell. Anon.       

Understanding Amethyst Gemstones

Amethyst is the purple variety of quartz and out of all of the quartz gemstones ranks at the top for desirability and value. Amethysts are pale pinkish-violet to deep reddish-purple in hue and are most often found as faceted gems, cabochons or carvings. Many rough forms are also used within jewellery including single crystals, clusters or slices of crystal-lined cavities known as geodes.

The most prized amethysts are known as Russian or Siberian amethyst, named after the fine specimens found in these localities. These have a good clarity and rich purple colouration with flashes of red.

Amethyst DreamscapeTM 53.37 ct cut by John Dyer & CO. Photo by Lydia Dyer Amethyst DreamscapeTM 53.37 ct cut by John Dyer & CO. Photo by Lydia Dyer

Amethyst Mythology and Meaning 

Historically, amethyst was kept as a talisman as it was believed to counteract the effects of alcohol. The word amethyst derives from the ancient Greek amethustos, which translates plainly to 'not drunk'.  

This mystical belief in amethyst in keeping one sober extends back to 320 BC to the poet Asclepiades of Samos, likely inspired by the wine-like colours of this gem. People believed that wearing an amethyst would save them from inebriation. The more affluent indulgers would sip from carved amethyst goblets or add powdered amethyst into their wine to keep their sobriety.

Amethyst - The Gem of Wine? 

This mystical power was argued as false by Pliny the Elder in the first century AD, however the belief continued for the centuries that followed. Inspired by its association with wine, the French poet Remy Belleau created a myth in the 16th century explaining how amethyst came into existence.

The poem speaks of Bacchus, the Greek god of wine and beautiful maiden named Amethystos, who refused the advances of Bacchus and prayed to the Goddess Diana to keep her chaste. To protect her, Diana transformed Amethystos into white crystal quartz. In frustration, Bacchus poured his wine over the crystals, dyeing them purple forevermore. 

Bentley and Skinner Amethyst Bracelet Bentley and Skinner Amethyst Bracelet. Image courtesy of Bentley and Skinner

The belief that amethyst is one of the worlds more precious gems can be linked back to antiquity. Amethyst was one of the twelve gemstones mounted in the Priestly Breastplate, cited in the Book of Exodus. It is from these 12 gemstones that the concept of birthstones developed. Christianity has used amethyst historically within the episcopal rings of bishops and other clergy to represent abstinence from alcohol. 

Amethyst - A Symbol of Royalty

In the Middle Ages, amethyst became a symbol of royalty and the rich purple of amethyst can be found within regal wardrobes and jewels across the world. A large domed amethyst can be found sitting atop the large Imperial Sceptre with Cross in our British Crown Jewels

The amethyst was considered a cardinal, or most precious gemstone, and was historically acknowledged in high regard alongside diamonds, rubies, emeralds and sapphires.

Cardinal gems held a value above all others due to their beauty and rarity. An abundant source of amethyst was found in Brazil in the eighteenth century and nowadays amethyst is widely accessible and ready to be enjoyed in all its regal beauty by gem and jewellery lovers worldwide. 

Read more Gem-A Birthstone Guides here

Do you want to know more about gemstones and the study of gemmology? Discover the Gem-A Workshops or speak to our Education team

Cover Image quartz amethyst rough crystal from the Gem-A archive. 

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Whitby Jet: A Discussion of its Simulants

Sarah Steele FGA DGA discusses the many simulants of one of Britain’s most famous native gemstones, Whitby jet.

If imitation is the sincerest form of flattery, then Whitby jet must be a very desirable material indeed. I can think of perhaps 20-30 different materials, both natural and synthetic, which, at one stage or another over the years, have been described as Whitby jet.

We think of a 40-year period during the mid to late nineteenth century as the heyday in Whitby jet manufacture, and from a jewellery output perspective that is unequivocally true. However, the desire for Whitby jet, and the quest to imitate it, has its roots much further back in time. 

Read more: Reconstructed Amber Broken Down

Following the Scottish Gemmological Association’s Conference this year, delegates had the opportunity to visit the 'Celts' exhibition at The National Museum of Scotland. I couldn’t resist the opportunity to join them in having a closer look at the museum’s stunning collection of Bronze Age jet neckpieces whilst we were there.

Historically, many of these early pieces containing black beads with high organic carbon content were described as Whitby jet. Modern analytical techniques have shown, however, that these almost always contain a variety of materials - Whitby jet, certainly - but also oil shales, lignites and cannel coals, often within the one piece of jewellery. 

Inchmarnock Bronze Age necklace showing use of multiple black materials. Photo credit Alison Sheridan. Whitby jet
Inchmarnock Bronze Age necklace showing use of multiple black materials. Photo credit Alison Sheridan

Whitby jet is a material with which the demand for rough will always outstrip supply in periods of high production, and jet collection requires patience as it is reliant on coastal erosion. Are we then, in the Bronze Age some 4,500 years ago, seeing the first example of a Whitby jet simulant? It has to be noted that the prevalence of Whitby jet in the archaeological record during this period suggests that it is arguably one of the oldest economic resources in the British Isles.

Fast forward 2,670 years and the Whitby jet simulant market is a fascinating and booming industry. British society is participating in a national obsession with mourning. With the death of George IV in 1830, the Lord Chamberlain’s office dictates the dress code for the period, stating unequivocally that “the ornament shall be jet”. In 1830 the term ‘jet’ meant only one material: Whitby jet. The death of the Duke of Wellington in 1852 prompted the production of Whitby jet jewellery into overdrive - the 50 recorded workshops in 1850 swelled to 204 following the death of Prince Albert in 1861, as yet another wave of mourning swept the nation. 

Read more: From Elizabeth I to Elizabeth Taylor with John Benjamin FGA DGA

Demand for rough Whitby jet was beginning to outstrip supply and other options were needed. The main attraction of Whitby jet as a gem material was of course its deep black colour and liquid-like lustre, but more importantly its low specific gravity (SG) 1.2-1.3. It was fine to look ‘weighed down’ by the convictions of your expression of mourning, but it was practical if the seven strings of beads you wore to denote that you were the seventh daughter of a deceased father, didn’t weigh more than a few ounces.

Therefore, to be a convincing simulant of Whitby jet, the imitation material would need to be light in weight. Whitby jet is also a poor thermal conductor and so always feels warm, as heat is not quickly transferred away from the surface. Today we often describe jet as feeling ‘plasticky’, however, in the mid nineteenth century plastic was yet to be discovered. The simulant therefore needed to be light in weight, black in colour and a poor conductor of heat. 

Horn and tortoiseshell

In 1712 John O’Bisset discovered horn could with the application of heat, be moulded into various shapes. When cooled the shape was retained - O’Bisset had discovered the first natural thermoplastic material. Sheets of horn were put between hot metal plates in a press and pressure applied. Placing the warmed horn into moulds before applying pressure enabled the production of horn boxes, beakers and other items. With the application of black dye, pressed horn was a good candidate for a simulant of Whitby jet and many jewellery items were produced. 

Horn has a tendency to delaminate due to its layered structure, so loupe examination often reveals these layers, especially on the reverse of brooches. Any damage to the edges also gives a slight transparency to the damaged area, which is not seen in Whitby jet. The colour can often seem uneven and it is not possible to screw a brooch fitting into jet. Therefore a screw, often seen in horn, is always a sign of a simulant. 

Pressed horn jewellery items. Whitby jetThe reverse of a pressed horn brooch showing lamination and screw fittings. Whitby jet
Top: Pressed horn jewellery items. Below: The reverse of a pressed horn brooch showing lamination and screw fittings

It is also worth mentioning that tortoiseshell, like horn, is also a natural thermoplastic. Tortoiseshell, a much admired decorative material, derives not from a land tortoise but from certain species of marine turtle, principally the relatively small hawksbill. Tortoiseshell is unlikely to be mistaken for jet due to the mottled colour, but the SG and ‘plasticky’ feel are similar.

Bog oak

Whitby jet is a fossilised wood, so perhaps a wood product could also make a suitable simulant. Bog oak is not a specific species, rather a term that indicates wood that has been buried in a peat bog for thousands of years. The extremely low oxygen conditions of the bog protect the wood from normal decay. While the underlying peat provides acidic conditions where iron salts and other minerals react with the tannins in the wood, gradually giving it a distinct dark brown to almost black colour. 

Bog oak jewellery. Whitby jet
Bog oak jewellery

Bog oak occurs in many areas of the United Kingdom but jewellery usually originates from Ireland. It was produced from the early 1800s but became popular in the mid nineteenth century, reflecting the demand for Whitby jet, especially after 1852, when techniques to mass-mould and decorate the material (through the application of hydraulic or heated pressure to the dried wood) were invented. 

Although predominantly used for mourning jewellery as a cheap substitute for Whitby jet, bog oak was also worn to support Irish crafts, with pieces often carved or stamped with Gaelic motifs such as harps or shamrocks - symbols not normally found in mourning jewellery. Concentric rings are usually visible on the reverse of items as blanks were lathe-turned prior to carving. Loupe examination always show the ligneous nature of the wood and the lustre achieved is usually textured and dull.

Vulcanite

In 1839 Charles Goodyear discovered the method of mixing sulphur with rubber to form hardened or vulcanised rubber, called Vulcanite. The proportion of sulphur can be increased or decreased in order to vary the required amount of hardening accordingly. Between 25-50% sulphur gives a hard product with the familiar feel of plastic. There are many Victorian vulcanite objects, but the most common form is an imitation of Whitby jet used widely in the production of brooches, bracelets and necklaces. Vulcanite could be produced in almost any colour, although the predominant colours are black (ebonite) and brown. As a result, vulcanite was by far the most widely-produced Whitby jet simulant. Unlike pressed horn a thermoplastic materials which, if heated again can be re-moulded into a different shape. Vulcanite is a thermoset material which, after moulding becomes brittle and cannot be remoulded. 

Vulcanite can be distinguished from jet relatively easily. If the material has been exposed to light over time it loses its black colour and becomes khaki brown. When rubbed, vulcanite smells strongly of sulphur and brooch pins are usually screwed into position rather than glued. Chain links only show one or two splits depending on the link style as the link can be twisted open and then closed. In comparison in Whitby jet links, where every other link in the chain is cut and glued and will always show two or three cuts depending on the style of link. As vulcanite pieces were often moulded from jet originals the same design is seen regularly and, with experience, can be identified easily. (Please note: the ‘streak’ test on vulcanite will reveal a light brown streak similar to that of hard Whitby jet and so should not be relied on).

Examples of vulcanite jewellery. Items with little exposure to light remain black (left). Items that have been exposed to light show the typical khaki colour (right). Whitby jet
Examples of vulcanite jewellery. Items with little exposure to light remain black (left). Items that have been exposed to light show the typical khaki colour (right)


Bois durci

In 1855 Francois Charles Le Page secured a French patent for a method of combining blood albumen from slaughterhouses, with wood powder to form a plastic mouldable material he called bois durci. The wood dust (either ebony or rose wood), was mixed with blood, dried and then ground to a fine powder. The powder was placed in a steel mould and steam heated to 150-250°C in a powerful hydraulic press. After half an hour the mould was plunged into cold water. The resulting wood product was an extremely dense, highly polished and resistant thermoset material. 

Le Page is reported to have used the marketing strapline “Anything Whitby Jet could do, bois durci could do cheaper and in brown”. The most common items available in bois durci today are circular plaques showing royalty or statesmen of the time. They are generally brown and often have bois durci stamped on the reverse.

French jet and Vauxhall glass

As far as Whitby jet imitations go French jet, along with vulcanite one of the most common. Glass items were also produced in large quantities during the Whitby jet heyday, primarily faceted black glass beads referred to as French jet. 

Its higher SG, vitreous lustre and glass moulding marks mean it is unlikely to confuse French jet with Whitby jet. However, because many of the designs were so innocuous, finding a nineteenth century piece of French jet and identifying it from a piece of black glass, used all the way through to the 1940s, can be difficult for collectors of the material. 

Vauxhall glass is often referred to as the English version of French jet, however all French jet was not of course produced in France! This thin highly reflective mirror glass was produced by a silvering process. The silvering is often seen on the reverse - either intact or in residual traces.

Spanish jet

Although all the above impacted the Whitby jet industry, it was a natural jet which was finally responsible for the industry decline. By 1870 the Whitby jet industry reached its peak, before catastrophically collapsing. There were undoubtedly a number of reasons. Some blamed the terrific demand, which had outstripped supply and lead to a fall in standards of workmanship, as many workers hadn’t had the basic training. The large number of simulants also cannot have helped, but the final death knell was heralded by the arrival from the continent of Spanish jet. It is hard to estimate how much of this material was imported from Asturias, but it is first documented in 1874 and many tonnes seem to have been available. 

The Spanish jet trade had flourished between seventh and sixteenth centuries, and whilst the Spanish supply undoubtedly had some very good quality rough material, it seems that Whitby imported a rather poor quality jet, often containing pyrite, making it unstable. Finished pieces degraded quickly, cracked and crumbled. As a result, consumer confidence in an already struggling product sector collapsed.

Three faceted bead necklaces, cracked and crazed beads, likely Spanish jet (left), Whitby jet, showing high lustre and sharp facet edges (centre), French jet with chips and abraded facet edges (right). Whitby jet
Three faceted bead necklaces, cracked and crazed beads, likely Spanish jet (left), Whitby jet, showing high lustre and sharp facet edges (centre), French jet with chips and abraded facet edges (right)


Decline of the industry

In 1889 the Whitby Gazette reported “It would have been better for the Whitby jet Industry, and better for art development, if the Spanish jet trade had never been known in Whitby”. Despite desperate measures to support the Whitby jet industry, such as a quality mark scheme, the industry didn’t recover. The mourning trend was well and truly over. 

In 1915 The Lady described the Whitby jet trade as “A somewhat funereal fetish of fickle fashion”. Poor recognition for the greatest lapidary trend our nation, and perhaps the world has ever seen. 

The beginning of the twentieth century may have heralded the end of the Whitby jet mourning jewellery trend, but it didn’t signal the end of the road for the use of plastics in jewellery. In 1899 we saw the introduction of casein formaldehye; milk curds hardened with formaldehyde giving us such famous trade names as Galilith, and of course in 1907 phenol formaldehye, with wood flour or other filler as powder gives us the trade name Bakerlite. Galilith and Bakerlite were never used to imitate Whitby jet jewellery - by this time (and forgive the pun) you wouldn’t have been seen dead in this outdated material.

It seemed like the end of the road for Whitby jet. The last apprenticed jet worker Joe Lyth died in 1958, and with him died the secrets of the Victorian era. However, the last 30 years or so we have seen a revival in fortunes within the Whitby jet trade. Today there are 11 manufacturers in Whitby town. As mentioned previously, demand for rough Whitby jet is high and patience is required for collection of beach material. This has allowed poor quality materials, primarily Siberian cannel coals and Georgian jet (both often referred to as Gagate) with its poor stability and high porosity to enter the supply chain. 

Georgian jet is becoming increasingly common as finished contemporary style jewellery made by Baltic amber manufacturers, and within the last 12 months as antique style beads from an undisclosed source. Attempts were even made to sell rough to unsuspecting workshops in Whitby. Experienced lapidaries however quickly identified the new foreign imposter. In Whitby we have no issue with Georgian manufactures producing items from their indigenous jet, but lack of disclosure of origin leads to the material being retailed as Whitby jet somewhere along the pipeline.

Nomenclature and appellation of origin is, as always, crucial to price. A good Whitby jet string of Victorian beads is worth £300 upwards, the Georgian imitation probably nearer £20, so caveat emptor!

As a lapidary in Whitby, I know that the Whitby jet trade will, as always fight back against the latest simulants. A true jet to rival the beauty or stability of Whitby jet has yet to be discovered, but it does make me proud to think that for the last 4,500 years Whitby jet has been held with such reverence that many have tried to emulate it. With the desire of the Victorians to find the perfect simulant, Whitby jet was in part perhaps responsible for the birth of the modern plastics industry, and therefore the modern world as we know it. ■

This article originally appeared in Gems&Jewellery May/June 2016 / Volume 25 / No. 3 pp. 16-20

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover image fine Whitby jet cameos including King Oswy and his bride (centre) and Bejamin Disraeli (right). Photo Credits Sarah Steele, except where otherwise stated. 


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

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Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

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Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

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Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

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Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

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Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

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Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

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Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

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Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

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Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


Additional Info

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The Tale of the Mouawad-Tereschenko Blue Diamond

Jack Ogden FGA looks into the story of the world's second largest blue diamond, the Mouawad Blue Diamond, previously known as the Tereschenko Blue Diamond. 

In the summer of 1984 David Warren, now Senior International Jewellery Director at Christie’s, received a phone call from the auction house’s bank manager with a question: “Do Christie’s sell blue diamonds? Our client has one the size of a pigeon’s egg.”

Mouawad-Tereschenko Blue Diamond

The huge gem turned out to be the Tereschenko diamond, one of the least well known large blue diamonds, and at 42.92 ct, just a shade smaller than the 45.52 ct Hope. It sold at Christie’s in Geneva in November 1984 for a then-record price of $4.6 million to Robert Mouawad and is now called the Mouawad Blue. Unlike the Hope and many of the other famous diamonds, it has lacked a romantic history.

There has been no curse or celebrated Mughal emperor to add notoriety or spice. The Christie’s catalogue, and Lord Balfour in his standard work on the world’s great diamonds, simply notes that the first known appearance of the stone was in 1913 when the Ukrainian Mikhail Tereschenko left it with Cartier in Paris. 

Read more: Harrods Unearths 228.31 ct Diamond from its Vaults for Private Sale

In 1915 he instructed them to mount it in a necklace, which was returned to him in Russia before being spirited out of the country again in 1916, on the eve of the Russian Revolution. Then according to Christie’s and Balfour, it passed into anonymous private ownership until it came up at auction in 1984. 

Perhaps we can now add some spice, even a curse, to this story, by introducing a French dancer born in the final decade or so of the nineteenth century. She entered the entertainment world under the stage name of Mademoiselle Primrose and by 1911 was performing in Le Théâtre des Capucines in Paris. She was renowned for her attractiveness and, in a rather surreal article on the components of female beauty in Paris that appeared in various American newspapers in late 1911 and early 1912, she was noted as one of the most beautiful of reigning stage beauties in Paris with particular praise for her “most charming chin”.

Suzanne Marie Blanche Thuillier ca 1920. Tereschenko diamond
Suzanne Marie Blanche Thuillier ca 1920

If Mikhail Tereschenko left the 42.92 ct blue diamond with Cartier in Paris in 1913 he may have encountered Mlle Primrose in that city. This is not such a wild suggestion because in 1924 we hear of a former Parisian dancer named Mlle Primrose, real name Suzanne Marie Blanche Thuillier, who had resided for a time in St. Petersburg, Russia, and who moved in Court circles there. She had left Russia for France just before the Revolution and was the owner of what was described as a 43 ct blue diamond, called by some the ‘Russian Imperial Blue’, and by others (rather bizarrely) the ‘Blue Diamond of Ceylon’.

The newspapers at the time gave myriad origins for the stone, neither verified nor mutually exclusive. It came from the eye of an idol in India; reached Russia in the time of Peter the Great; had been set in the Russian Crown Jewels; had been secretly purchased in London “under romantic circumstances” and so on. 

One newspaper even hedged its religious bets and said the gem had “ornamented the finger of Buddha in a Hindu Temple". Particularly intriguing is a report in a British newspaper that "In April 1912, there were rumours in Hatton Garden that a diamond merchant was walking about with a quarter of a million in his wallet. In fact he had received from his Dutch agents a stone [a large blue diamond] which had been sent from America with instructions to let it fetch what it would."

This merchant supposedly pieced together the history of gem, found out that it had once belonged to the Russian Imperial family and put out feelers, which reached the then-Czar who sent an emissary to obtain it. Perhaps more about this supposed transaction will come to light, but in the meantime we can observe that a presence on the market in London in 1912 would tie in nicely with Tereschenko depositing a large blue diamond with Cartier in Paris in 1913.

After Mlle Thuillier and her diamond reappeared in France, some newspapers reported that she had been given it by Czar Nicholas as a token of his regard for her; others that it was given to her by "a member of the Imperial Court of Nicholas".

The latter view was supported by those in the know who vehemently denied, or expressed indignation, at the suggestion that the late Czar gave Thuillier the diamond. Indeed, according to Le Parisien newspaper in June 1924, when directly asked where it came from Thuillier explained “evasively” that strictly speaking she was not admitted to the imperial court, but “frequented assiduously with the gentlemen of the court who occupied the highest positions”. She never claimed that the diamond was presented to her by the Czar. So, if a gentleman other than the Czar gave her the gem, Mikhail Tereschenko is perhaps a potential contender. 

Was a gift of the blue diamond the ticket to a new life outside Russia on the eve of the Revolution? She reportedly arrived in Nice in the South of France in 1916 and pawned it there that same year. The diamond had travelled in a secret pocket of her sealskin coat. 

Following her arrival in the South of France, Mlle Thuillier’s beauty and attire "made her a spectacle among the many lovely women". However, she gambled excessively and this "most notoriously extravagant woman in Europe" inevitably got into debt and had to pawn the blue diamond more than once. In June 1924 the diamond was in pawn for 200,000 francs with creditors circling, but there was the expectation that it would be redeemed and available for purchase. Apparently a Parisian dealer had already offered £125,000 and an American woman £200,000. 

The Tereschenko or Mouawad Blue Diamond
The Tereschenko or Mouawad Blue Diamond

What then occurred is unclear. There are reports that a Joseph Paillaud of Cap d’Ail, near Nice, had put up collateral of 1,350,000 francs and would take ownership of the diamond if not repaid in full by 9 December 1924. Mlle Thuillier made a plea to the Court and in March 1925 the Civil Court in Nice removed it from Paillaud’s possession.

Apparently Paillaud’s actions equated with acting as a pawnbroker, an activity for which he was not licensed. A police search of his house - named, ironically, Chalet Russe (Russian Chalet) - revealed numerous pieces of jewellery lacking the required hallmarks plus records of transactions that were not properly registered.

Mlle Thuillier might well have predicted Paillaud’s bad luck. A newspaper report in 1929 recounted that she had believed the diamond to be cursed. This may be typical press sensationalism, but some accounts say she was something of a mystic with an interest in the occult and in 1924 was even considering taking the gem back to India so it might be replaced on the statue of Buddha from which it had been robbed. It clearly never made it back to the statue and the last we hear of the large blue diamond is in March 1925, in the custody of the clerk of the civil court in Nice.

The last we hear of the celebrated Mlle Primrose - with her charming chin - is in jail in Nice in April 1929, after several years of dire poverty. Her desperate situation had driven her to forgery. What happened to the large blue diamond from 1925, until it resurfaced at Christie’s Geneva in 1984 is so far unknown, but a French newspaper in 1924 had already commented that the diamond had "undoubtedly not yet finished the cycle of events of its adventurous life". 

Note: The above was compiled from contemporary press accounts from Europe and America. Their lack of accuracy is demonstrated by their confusions and contradictions, so for now this is a tale of the Mouawad-Tereschenko diamond, not necessarily the tale of the Mouawad-Tereschenko diamond 

This article originally appeared in Gems&Jewellery March/April 2016 / Volume 25 / No. 2 pp. 32-33

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover image an exact CZ replica of the Mouawad blue.


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


Additional Info

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Beginner's Guide: What Can Emerald Inclusions Tell Us About Origin?

Emerald has long been one of the world’s most popular and valuable gemstones. Since the times of the Ancient Egyptians, emeralds have been viewed as tokens of good fortune and harbingers of new beginnings and rebirth.

While emeralds are fascinating from a historical and culture perspective, they are equally exciting for gemmologists, particularly when it comes to characteristic inclusions.

Birthstones Guide: Emerald for those Born in May 

A variety of green beryl, the name 'emerald' is derived from the Greek word smaragdus (meaning green). The green colour of emerald is caused by traces of chromium, but vanadium may also be present in some stones.

Today, emeralds can be found in Colombia, Brazil, India, Pakistan, Siberia, South Africa, Zambia and Zimbabwe.

Read more: The 'Emerald Desert' of Western Australia

The inclusions contained in almost all natural emeralds are very useful in distinguishing them from synthetic emeralds and other green stones. The types of inclusions in some emeralds can offer an indication as to their origin - although this is certainly not a foolproof method.

Typical Emerald Inclusions 

As you examine more emeralds, either during your studies or out in the field, consider the following localities and the typical inclusions and features that material from these regions can present.

LocalityTypical Inclusion and Features
Colombia Three-phase inclusions (liquid-filled cavity containing a crystal and a gas bubble)
India Two-phase inclusions (liquid-filled cavity containing a gas bubble)
Zimbabwe Tremolite (usually fibrous or neddle-like crystals)
Siberia Needle-like crystals of actinolite
Many Localities Mica flakes, pyrite and calcite, and also colour zoning

Examples of these inclusions can be found in the images below, taken by Gem-A tutor, Pat Daly. 

Three-phase inclusion. Image courtesy of Pat Daly.
Three-phase inclusion in emerald. Image courtesy of Pat Daly.

Two-phase inclusion. Image courtesy of Pat Daly.
Two-phase inclusion. Image courtesy of Pat Daly.

 Needle-like inclusion. Image courtesy of Pat Daly.
Needle-like inclusion. Image courtesy of Pat Daly. 

Pyrite inclusion. Image courtesy of Pat Daly.
Pyrite inclusion. Image courtesy of Pat Daly. 
Mica inclusion. Image courtesy of Pat Daly.
Mica inclusion. Image courtesy of Pat Daly. 
Crystal inclusion. Image courtesy of Pat Daly.
Crystal inclusion. Image courtesy of Pat Daly.

When combined with other assessments, such as the refractive index and specific gravity, these inclusions can give an indication as to the country of origin. ■

Interested in finding out more about gemmology? Discover our courses and workshops here

Cover image needle-like inclusions in emerald. Image courtesy of Pat Daly. 


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


Additional Info

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What Makes the Alexandrite Colour-Change Effect so Special?

Sometimes known as ‘emerald by day, ruby by night,’ the gemstone alexandrite is a marvel of nature and the alternative birthstone for those born in June. Here, Julia Griffith FGA DGA EG explores the history, properties and colour change effect of this fascinating gem.

Alexandrite is an extraordinary gemstone that appears green or red dependent on the light it is observed under. This colour change effect is sometimes referred to as the ‘alexandrite effect’. The rarity of this material and its chameleon-like qualities make alexandrite one of the world’s most desirable gemstones.

What Makes Alexandrite Valuable?

Alexandrite was discovered in 1834 alongside beryls within the prestigious emerald mines of the Russian Ural Mountains. It is part of the chrysoberyl family, which is separate to beryls, being a beryllium aluminium oxide as opposed to a silicate. Chrysoberyls have good durability and a hardness of 8.5 on the Mohs scale, making them perfect for use in jewellery. This all depends, however, on whether you can find an alexandrite to begin with!

Alexandrite Gem A Conference Evan Caplan Photographed at the Gem A Conference 2017 Gem A BlogA large alexandrite specimen presented by Evan Caplan at the Gem-A Conference 2017. Photograph by S Dowthwaite FGA DGA on Instagram.

Alexandrite is so rare that it has never truly been the main aim of commercial mining. Instead, it is a happy ‘by-product’ as the likelihood of uncovering it in any significant quantity is very, very slim. In Russia, just one crystal of alexandrite was found for every hundred-or-so emeralds.

Read more: What Can Emerald Inclusions Tell Us About Origin?

Clarity is poor in the majority of alexandrites – they are commonly riddled with fractures and appear translucent to opaque. Such specimens have little value and are often unusable as gems in jewellery. Rough specimens over five carats in weight are also scarce and most alexandrites found on the market are under one carat. Prices for fine specimens above a single carat will rival or surpass fine quality rubies, emeralds and even diamonds, making them one of the most expensive and rare gemstones in the world.

The Alexandrite Colour Change Effect

The most important factor for alexandrite is the quality of its colour change. The most prized colour change is a strong raspberry red in incandescent light and a bright green in daylight - however an absolutely perfect specimen is not known to exist!

Alexandrite in daylight gamma rayAlexandrite photographed in daylight.

Alexandrite in tungsten alpha rayAlexandrite photographed under incandescent light.

The colours seen in alexandrite are caused by chromium – the same colouring element that causes the red of ruby and the green of emerald. The amount of colour change observed is often given as a percentage - with a 100% colour change from one hue to the other being the most valuable. The hues seen can also vary; if they stray too far from the expected colours of alexandrite or if the amount of colour change seen is minor, the value will be significantly affected and it is debatable as to whether it can be classified as an alexandrite at all.

Read more: What Makes a Gemstone Rare?

The colour change effect is due to alexandrite transmitting green and red light equally. Incandescent and daylight light sources are richer in different wavelengths (red or blue and green respectively) and this has a direct effect on what colour the gemstone appears to the human eye.

Alexandrite Pleochroism

Alexandrites are also noted for their strong pleochroism. This is an independent optical effect from colour change, in which the gem will appear different colours from different directions. In alexandrite the pleochroic colours are green, orange and purple-red.

Alexandrite Origin

The finest quality alexandrites are said to be from the original deposits in Russia, which were mined out in the 19th century. The name ‘Alexandrite’ was chosen to honour the Russian Tsar Alexander II. Legend states that this rare and beautiful stone was found on the day the heir became of age on his 16th birthday.
The vibrant red and green colours observed also mirror the colours of the national military of Imperial Russia. This led to alexandrite being named the official stone of the Tsardom of Russia.

Chrysoberyl AlexandriteAnother example of the colour change effect in alexandrite.

According to Russian legend, wearers of alexandrite reap many benefits including good luck, good fortune and love. A popular belief is that alexandrite helps the wearer strive towards excellence by bringing concentration, discipline and self-control.

Nowadays, alexandrites are mined from Brazil, Myanmar, Tanzania, India and Madagascar. Sri Lanka has also produced some fine specimens - the world’s largest faceted alexandrite hailed from this locality and is a whopping 65.7 carats. A further rarity is chatoyant or ‘cat’s-eye’ alexandrites, which are cut in cabochon to reveal this optical effect.

Alexandrite Synthetics

Alexandrite has such extreme rarity that those seen on the market might not be quite what they seem. Alexandrite has been successfully synthesised in laboratories since the 1960s and these synthetics have the same chemical, physical and optical properties of natural alexandrite and show a strong colour change.

The most common simulant is synthetic colour change sapphire, which shows a greyish blue to pink colour change. At just a dollar or two per carat - it is extremely common on the market. This material has been made since 1909, so is often found in antique pieces of jewellery.

Chrysoberyl Alexandrite Synthetic Flux GemA 0200An example of synthetic alexandrite.

A good colour change, good quality, transparent natural alexandrite could easily cost the consumer a five figure sum per carat and beyond. This, however, is a fine price to pay for such a spectacular and exceptional gem. ■

Do you want to find out more about gemstones and understand their physical and optical properties? Start your gemmology journey with the Gem-A Gemmology Foundation course.

Save the date! The Gem-A Conference takes place annually in November. Find out more about this year's Gem-A Conference, here.

Cover image: Gemmology in action at Gem-A. Image by Henry Mesa.

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Gem Careers: A Lifetime of Expertise

Rosamond Clayton FGA DGA FIRV MAE, a gemstone specialist and jewellery valuer, is often called upon as an expert witness in trials to identify and value precious stones. 

When did you get started in gemmology?

I had been working in Hong Kong on a contract posting when I married in the 1970s and I needed to find a new and interesting career. Fortunately, my search for a fulfilling subject to study coincided with the arrival of Marcia Lanyon FGA in Hong Kong, whom I met at a friend’s house one evening. 

I was soon enrolled on a foundation gemmology course and quickly became a fanatic. Many in our trade will recognise this ‘disease’. When I visited China in 1973 for a business trip with my husband, we were each only allowed 15 pounds of luggage, including handbag and camera; Webster’s Gems formed part of this allowance! 

I took my foundation exams in Hong Kong in 1974 and passed, but it was diamonds that interested me and therefore I needed to study for the Diamond Diploma. I was helped by Noel Deeks FGA DGA who taught the practical diamond grading at Sir John Cass College in London, but there was nowhere to study in Hong Kong, so I partly commuted to London (subject to load on British Airways). Noel Deeks introduced me to a Mr Shun Wai Woo FGA DGA, the only DGA in Hong Kong at the time, who worked in a senior capacity with his cousin, who had started the only diamond manufacturing company there. 

In addition, through a friend, I was introduced to Bill and Joan Hsu who had studied the residential GIA diamond course in Santa Monica and returned to Hong Kong to run a diamond wholesale business. I went to their office at least once a week and graded all their stock; they taught me how to survive in business in Hong Kong. 

How did you transition to the world of valuations?

When Marcia Lanyon left Hong Kong she passed her consultancy work with the Hong Kong tourist association on to me, so by this time I knew most of the retailers. My boss at the time, a shrewd Chinese business woman, saw an opportunity to open up new accounts with these retailers. After three years I moved to a retailer in Kowloon on the mainland, called Tse Lee Yuen. 

Rosamond Clayton in Hong Kong, 1981. Image courtesy of Rosamond Clayton.
Rosamond Clayton in Hong Kong, 1981. 

One Monday I was instructed by my employer that I would become the valuer! I was to value all the customers’ diamonds and jadeite. My protests fell on ‘dead ears’ as I was told my English was better than my Chinese colleagues’ and the valuations had to be written in English – there were no typewriters with Chinese characters – therefore there was no argument. 

How did your own business evolve?

In 1985 I set up my own valuation business in Hong Kong, which I sold when I returned to the UK in 1987. Initially, on return to the UK, I rented space with jewellery designer John Donald at 120 Cheapside who I knew through Marcia Lanyon. It was a matter of going back to the start on the Monopoly board, only saved by the fact that the NAG and Gem-A were housed together in Carey Lane (in close proximity to Cheapside), and I was soon taken under the wing of Philip Stocker FGA the NAG in-house valuer. He introduced me to the Academy of Experts, who provide training for those taking instruction as expert witnesses. 

Have there been any memorable moments that really stand out?

I have always enjoyed travelling abroad for work and my most memorable business trip was for a Chinese friend, who was chairman of a marine diamond mining company in Namaqualand, looking at the possibility of cutting diamonds mined there in Hong Kong or New York, where he lived. 

My cousin was working as a commercial pilot in South West Africa (now Namibia), so I flew to Windhoek with a commercial airline and she flew me from Windhoek to the mine in a Beechcraft Bonanza. We stayed the night at Okiep near Springbok, about 500 miles from Windhoek and the next day to De Punt, North of the Oliphants River. 

Loughborough 2002 Valuer of the Year. Image by Vicky Morrison.
Loughborough 2002 Valuer of the Year. Image by Vicky Morrison.

In earlier times this river was much larger and brought the diamonds down, it is thought from Lesotho, exiting into the Atlantic and carrying the diamonds north with the current, in the same process as the Orange River at a later stage. Due to the rough sea conditions, the members of the mining franchises were only able to dive on average four times a year and I was fortunate to be there on one of these occasions. Apart from a substantial yield of fine quality diamonds they brought up crayfish for our evening barbecues. 

Can you tell us a little bit more about your profession and what makes it unique? 

I had been instructed as an expert in jewellery cases in Hong Kong and this work in the field of gemstones and jewellery had always held the greatest interest for me. Importantly, it is necessary to train to supply reports as an expert witness in court proceedings and it is now becoming a requirement by the courts, not merely a wise precaution. The cases are varied but the civil cases frequently involve post loss assessment, divorce or some aspect of alleged unethical trading. 

A case set down for a High Court hearing can last a number of years from the preliminary report to additional reports in light of new evidence, experts meetings and finally the hearing which can frequently last a week or a number of weeks. A great deal of research is required, sometimes many months just for one item. No other type of valuation work provides this opportunity. 

What would your advice be for anyone who wants to get into what you do? 

For aspiring valuers today it takes time to obtain the required qualifications and experience and the process may seem costly. However, it would be hard to find another field of interest with so many enthusiastic and generous people willing to give their time and knowledge. As a valuer, even once the initial qualifications are obtained, without the wealth of knowledge available and help from those in specialist fields, it would not be possible to operate. In addition there is not a moment to lose in grasping every opportunity for further knowledge and training in every aspect of our rich world. 

My own career in the field of gemstones and jewellery has been a long and challenging path and, at the outset, I had not entertained the idea of being a valuer but I believe that there has been a revolution in the methodology of jewellery valuing in the UK and I am proud to be a part of it.

Rosamond Clayton at the London Diamond Bourse in 2016. Image courtesy of Rosamond Clayton.
Rosamond Clayton at the London Diamond Bourse in 2016. 

Top Tips: Becoming a Valuer

Essential qualifications:

Gemmology, diamond grading, Certificate of Appraisal Theory (CAT - the NAJ’s self-learning programme on valuation methodology). Join the National Association of Jewellers Institute of Registered Valuers (NAJ IRV). 

Concurrently with obtaining qualifications:

Try to obtain experience with a diamond wholesaler, coloured stone wholesaler or manufacturer. 

Network:

It is impossible to operate even as an experienced valuer without contacts. Visit auction houses, museums, attend lectures and most importantly attend The NAJ Loughborough Conference where workshops and lectures are provided on every imaginable valuation topic. ■  

Gem-A members can log in to read the full article Gems&Jewellery Spring 2017 / Volume 26 / No. 1

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover image Rosamond Clayton and her colleagues from the Institute of Registered Valuers. All images courtesy of Rosamond Clayton. 


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


 

Additional Info

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How to Assess the Value of an Opal: A Beginner's Guide to Pricing

Although once known as 'bad luck', opals are fast becoming one of the most sought after gemstones in jewellery collections. But what makes one opal worth thousands and others mere pounds and pence?

Here, Gem-A Instruments manager, Samatha Lloyd FGA EG, offers a quick but essential guide to opal value factors and what distinguishes a fantastic specimen from an average one. 

COLOURS IN OPAL

Opal is composed of uniform spheres of silica, which form a grid-like structure. The spaces between these spheres contain a silica solution. When light passes through the spheres and hits the silica solution, it is diffracted, producing differing rainbow hues.

Read more: The Different Types of Opal

Colour play depends on the size of the spheres, for example, smaller spheres result in blue colours, but orange and red will be present when they are larger. The more uniform the grid-like structure, the more intense the colours will appear.

Australian Opal. 

TYPES OF OPAL 

Customers may be most familiar with light opal, which makes up the majority of mined opal. It has base colours that range from white, to milky white and light grey, with varying degrees of colour play dancing on top.

If the body of the opal is transparent – also known as light crystal opal - the colour patches can be seen below the surface. It is these specimens that command exceptionally high prices. Your customers may also be familiar with black, or dark, opal, which has a dark body colour - sometimes enhancing the brilliance of the colours. This is the rarest and most valuable opal variety. 

OPAL VALUE FACTORS 

There are a number of factors that alter the value of opals. As mentioned, black opal can command higher price points than light opal (especially with an inky black body tone), although this is not to say that a fantastic light opal cannot be more expensive than a mediocre black opal. 

The brightness and brilliance of an opal is particularly important for its value, even if it is average in other areas. Therefore, lots of colours flashing on a dull stone may not command the same value as a gem with a higher degree of brilliance. 

Australian opal.
Australian opal.

We have already hinted at transparency, but this is also an important value factor. Light opal is much more desirable if it is transparent, with crystal opals with vibrant colours being particularly prized. 

A secondary and more complex layer of value arises when considering colours. The ‘dominant colour’ in an opal can affect its value, with red commanding the highest cost, followed by orange, yellow, green, blue, indigo and violet. However, do not forget, a blue-green brilliant stone will be more valuable than a dull red. 

OPAL PATTERNS 

In some rare cases, the diffraction of light within an opal can cause interesting patterns to arise. These patterns can increase the value of a stone. ‘Pinfire’ and small dot-like patterns are less desirable than bold ones, such as stripes, peacock feather shapes and broad brushstroke-like flashes of colour. 

Australian opal.
Australian opal.

 

ETHIOPIAN OPAL VS AUSTRALIAN OPAL

Customers may ask why one opal costs thousands of pounds, while another is mere hundreds or less. The answer could lie in its origin. Australia is a phenomenal source of opals and produces some of the world’s most incredible specimens.

Crucially, opals from this region have a lower water content, which means they are less susceptible to drying-out and less likely to exhibit ‘crazing’ - hairline fractures that impact the durability of the stone.

In contrast, Ethiopia is a newer source of opals, but some material has been found to have a much higher water content, making it unreliable and potentially unsuitable for jewellery. 

Ethiopian opal.
Ethiopian opal.

With thanks to Hatton Garden-based gemstone supplier, Marcus McCallum FGA, for taking these striking photos of Ethiopian and Australian opals.

Read more facts in The Opal Story by Andrew and Damien Cody, available in the Gem-A library. ■  

Gem-A members can log in to read the full article Gems&Jewellery Spring 2017 / Volume 26 / No. 1

Interested in finding out more about gemmology? Sign-up to one of Gem-A's Short Courses or Workshops.

Cover image example of Australian opal. All images courtesy of Marcus McCallum. 

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Natural vs Enhanced: Navigating Lapidary Materials

Helen Serras-Herman FGA guides us through the varieties of all-natural and enhanced gem materials, highlighting key treatments and their impact on the marketplace. 

There is an endless inventory of lapidary gem material on the market today, created or enhanced to look like other natural materials, usually one that is rare and expensive. Most of these enhanced materials are natural materials that have been dyed or compressed to simulate a better quality material, while some are partly natural stone and partly other materials, such as resins and metals. There are also natural materials that have been dyed to a completely different colour in order to look like another natural material, which we could call ‘look-a-likes’. All these simulants provide an inexpensive alternative to natural gems, and many of them are beautiful, with bold patterns and durability. 

The only problem surrounding these stones is disclosure, or the lack of it. Dealers should always let their customers know exactly what they are buying. Even though many times the original wholesaler or lapidary may have disclosed information about the nature of the rough, cabochons or beads, somewhere down the line, or online, information gets buried or blurred. 

One of the reasons for disclosure, besides honesty, is for the customer to know how to take care of the finished stones. The customer may be the lapidary, designer, metalsmith, the final jewellery client or collector. Disclosure helps determine how well stones will wear once set into jewellery, whether they should be set into rings (which take more abuse) or pendants and brooches, or how will they survive in an ultrasonic cleaning machine. 

Turquoise Sky necklace made by Helen Serras Herman.
Turquoise Sky necklace made by Helen Serras Herman: The carved turquoise in this 'Turquoise Sky' pendant, set in sterling silver with orange sapphires from Montana, is from the Hatchita Mine in Southwestern New Mexico, showing natural beautiful golden-colour matrix inclusions.

According to the Federal Trade Commission (FTC) guides for the jewellery industry, with the exception of normal fashioning (cutting and polishing), it is the seller’s responsibility at all levels of commerce to clearly disclose to the buyer at the time of the sale whether the stone is natural or not, and about any enhancements. 

While many articles focus on disclosure of enhancements of faceted rubies, emeralds or diamonds, the cabochon and bead market slides almost quietly under the disclosure radar. 

NATURAL TURQUOISE VS STABILISED & COMPRESSED TURQUOISE 

Turquoise is a beautiful gemstone found in several places around the world. As one by one the famous Arizona turquoise mines close - Bisbee, Sleeping Beauty - there are not too many options left to source the all-natural material, which is sought after and appreciated by lapidaries, gem collectors and jewellery lovers alike. Hard, all-natural turquoise is probably less than 3% of all turquoise sold today. 

The vast majority of turquoise on the market has been stabilised with polymers in order for the stone to harden, a permanent treatment. When dyes are added to the resin, the turquoise is referred to as ‘treated’ instead of ‘stabilised’. 

Blocks by Colbaugh Processing Inc.
Blocks by Colbaugh Processing Inc. A variety of compressed natural turquoise blocks is offered by Colbaugh Processing, including turquoise with bronze, Mohave purple turquoise with and without bronze, and Mohave green turquoise with and without bronze. 

A rarer form of turquoise comes in a compressed type. Small, natural nuggets of quality turquoise are compressed with resin into blocks. The outline of each nugget is still visible. There are no dyes in these blocks. These blocks are created by Colbaugh Processing Inc, a very-well known company owning the only active mine for turquoise in Arizona, the Kingman mine. They also create compressed blocks of natural turquoise nuggets infused with bronze or zinc that offer a very unique look, simulating natural turquoise with golden web inclusions. A dyed bright green turquoise block is also available, with or without infused bronze, simulating the rare bright green gaspeite from Australia. 

NATURAL LAPIS VS ENHANCED VS SIMULANT 

Lapis Lazuli is a striking rich blue opaque rock, composed of several minerals; lazurite, calcite veins and pyrite crystals are the most predominant. There are only a few well-known mining areas in the world producing fine quality lapis: Russia, Chile and Afghanistan, and they are all ancient deposits. 

Magnesite (left) vs. lapis lazuli (right)
Magnesite (left) vs. lapis lazuli (right)

Pale and mottled material is successfully marketed as ‘Denim lapis’. Lapis should be kept away from heat and chemicals, especially in the event that the stones, carvings or beads may be dyed. Simulants include a brightly-coloured man-made lapis crushed for inlays, and magnesite from China, a soft and porous material, dyed blue with added metallic inclusions that simulate pyrite, that truly looks like natural lapis. 

RAINBOW CALSILICA 

Rainbow Calsilica is a manufactured material created and sold by Colbaugh Processing Inc. The material imitates natural quartz with veins of blue chrysocolla and red jasper found in copper mines in Arizona. This colour combination is rare making the natural pieces highly prized. 

Rainbow Calsilica, natural vs. man-made.
Rainbow Calsilica, man-made (left) vs. natural (right): Rainbow Calsilica is a manufactured material made of pulverised calcite mixed with pigments and stabilised with a polymer, imitating quartz with veins of blue chrysocolla and red jasper.

Tests were undertaken on samples of Rainbow Calsilica at the SSEF Swiss Gemmological Institute laboratory in Basel in 2002. Their final report, as referenced in the GIA’s Gems & Gemmology magazine in 2002, states that “the samples examined appear to have been made of pulverized carbonate rock (calcite) mixed with pigments and stabilised with a polymer.” 

CONCLUSION 

As lapidaries, designers and collectors, we always look for new gem materials to incorporate into our artwork. The list of all natural materials is shrinking daily, and the variety of enhanced lapidary materials on the market today is almost overwhelming. 

The better we understand these materials, the better we will be able to sell them to our customers. Today’s gem and jewellery consumers are educated, and look up to artists and jewellers to alert them about the natural origin of the materials or the technological enhancements that made these lapidary gem materials available, affordable, durable and appealing. ■ 

Gem-A members can log in to read the full article Gems&Jewellery Spring 2017 / Volume 26 / No. 1

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover image Mohave purple turquoise blocks: Mohave purple turquoise has become very popular and is made from natural turquoise compressed with resin, then dyed and stabilised. All images by Hellen Serras-Herman. 


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


 

Additional Info

Read more...

Field Trip: The 'Emerald Desert' in Western Australia

Author, British jewellery designer and Gems&Jewellery contributor Joanna Angelett describes her recent gemmological trip to Western Australia.

We decided to take a trip to the 'Emerald Desert' in Western Australia, to look for emeralds. After arriving at Kalbarri National Park and spending a week, surrounded by its stunning pristine beauty, it was not a very short leap from there to our emerald destination - about 600 km – and setting off at 5am we reached Mount Magnet, renowned for iron and gold mining, before day-break.

Navigators on the way to the Emerald Desert.
Navigators on the way to the Emerald Desert.

To reach the Poona emerald mine we drove another 200 km from Mount Magnet to Yalgoo. Alluvial gold was discovered in Yalgoo in the early 1890s but then in the first part of the twentieth century, emeralds were discovered.

A variety of the mineral beryl (Be3Al2(SiO3)6)  - green in colour due to the traces of chromium or vanadium - were found in the Warda Warra in the Yalgoo Goldfields. But it is the Poona deposit, which has always been considered the most productive in the region. Several other, much less significant deposits like Noongal, Menzies and Warda Warra in the Yalgoo Goldfields (names from the Aboriginal language) discovered small unnamed occurrences of mostly milky-opaque emeralds, richly filled with cracks and inclusions and thus appeal mainly to mineral collectors, scattered across the Emerald Desert in a radius of more than 200 km around Poona.

The owners of our hotel told us they have relatives in almost every mining town of the Goldfields' surroundings, and locals filling the bar, mainly miners, gave us plenty of advice on how to reach the Poona emerald mine and how to prepare for this expedition. The owner gave us a present - a huge crowbar. "It will help," he said, and it really did!

Eugene Trimmer fossicking.
Eugene Trummer fossicking.

In the morning it seemed that the entire town knew "these people from London are going to dig for emeralds in the desert". They waved at us as we filled our 4x4 with endless bottles of mineral water, and even when we drove through the town.

Equipped with hand-drawn maps, it was just 150 km to Cue - a cosy town of 300 people - surrounded by golden mines, big and small, and then another 70 km on an uneven track to the mysteries of Poona's Aga Khan Emerald mine, named after a member of the Iranian royal family Sultan Aga Khan III. 

The gold mines with the highest productivity lie right on the doorstep of Cue and as soon as we passed this tiny, tidy town, we found ourselves in a land beautified with all shades of gold. It was impossible not to take photos of Cue's numerous gold mines from the distance and close up, especially after we were shown a huge gold nugget by a Cue resident, who had found it in the area several years ago and who ever since has worn a nugget around his neck as an amulet. 

Golden amulet belonging to a Cue resident.
Golden amulet belonging to a Cue resident.

We were told by locals that the best sign for those off fossicking, is to meet the potentate of the desert and master of all its treasures - the Golden Coins King - the beautiful and rare lizard 'dragon' of the Emerald Desert, who it is said leads to great fortune.

Golden Coins King of the Emerald Desert. Image courtesy of Eugene Trimmer.
Golden Coins King of the Emerald Desert. 

Certainly we had been waiting all the way for such a sign and when, we saw the Golden Coin King at first we did not believe our own eyes, but it was real. Even getting the opportunity to take a picture of the Golden Coin King was magical.

After a couple of miles along a narrow bumpy path, we finally discovered an abandoned runway and a bit further on, a now irrelevant warning: 'Danger Active Mining Area Keep Out'. One more mile and we were honoured by the chance to see and enjoy Pegmatite's field.

In Poona emeralds occur in both mica schist and quartz pegmatite matrix. The best emeralds were found here during the active mining period of 1960 to late 70s, in a mica schist adjacent to the quartzose beryl-bearing pegmatite, where some crystals were gem quality, and huge boulders of perfect quality snow-white quartz were found scattered across the area. 

Our mineral collectors' enthusiasm gradually shrunk as the day wore on and the hope of finding a huge sparkling transparent emerald of a saturated green began to shrink.

But sometimes a small surprise find can bring greater gratification than an expected large one, and it happened this time; we found a milky-green crystal, almost invisible amongst the mass of brightly coloured rocks sparking in the sun, but in our eyes it was invaluable.

Milky green emerald find.
Milky green crystal of emerald.

Sunny and golden Western Australia slowly abated into the bustling heart of London, where our designer studio is based in Hatton Garden and the arrival of the Poona emerald was eagerly awaited.

From the very beginning there was no doubt what kind of design this opaque emerald demanded, but primarily it was necessary to release it from the matrix. When dealing with one of the most fragile gems, this it is not an easy task.

Although some of Poona's crystals are gem quality, they are still quite undistinguished in size, with only one exception in 1971: an 138 carat transparent emerald was found and widely published in the WA press. Gemmologists Perry and Levinson were engaged to separate the emerald from the biotite matrix.

Despite their best efforts the stone cracked and split into two unequal parts of 118 and 20 carats. This type of matrix makes the extraction of emeralds very difficult, which made mining in Poona an unattractive commercial quality.

Gems Merchant with emerald rough ring from the collection 'The Characters' by Joanna Angelett. Image courtesy of Eugene Trimmer.
Gems Merchant with emerald rough ring from the collection 'The Characters' by Joanna Angelett. 

We remembered this story, when our emerald broke in two parts during our attempt to release the green jewel from the tenacious rock, but in this case it did not spoil our plan. The ‘Gems Merchant Captain’ ring shoulders half of the emerald and represents Poona’s rough supplied to Sultan Aga Khan III, telling the story of the wondrous emerald desert of Australia. ■ 

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover image the broken emerald. All images copyright of Joanna Angelett.


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


 

Additional Info

Read more...

A Man of the Ocean: Diving for Organics with Eric Fritz

In a recent trip to the London headquarters, Eric Fritz, FDGA DGA manager of North America for Gem-A stopped by for an industry insider Q&A, educating us on theoretical and practical guidance of organic materials. Sarah Salmon speaks to the man of organic passion exploring the nature of these beautiful materials.

With a passion for pearls, a deep love for shells since the age of four and an extensive knowledge of coral, minerals and gemstones, Eric Fritz reveals his top tips when it comes to his specialty: organic gem materials.

Q. When identifying pearl, what are Gemmologists looking out for when grading their quality?

For value, you will be looking at whether it is a salt-water or freshwater pearl, whether it is natural - formed without any human involvement - or whether the pearl has been cultured. The most valuable in terms of quality across the board would be natural saltwater pearls. This would then be followed by natural freshwater pearls, saltwater cultured pearls to freshwater cultured pearls.

Roundness is also preferable when grading a pearl where the more perfectly round and larger it is without blemishes, the more precious it is considered. The bigger the pearl, provided it still has a good ‘roundness’ and lustre finish to it with minimal spots and blemishes to it, the more desirable and valuable it becomes.

Q. What causes the blemishes and imperfections to form on a pearl?

The blemishes are caused by the formation of the organic material itself. Formed by living organisms which, just like us are made up of a range of different imperfections, gives each pearl its unique, flawed composition. The living environment of the shellfish is also a key factor where surrounding waters may contain disease or the shell mechanism itself may malfunction; all of which directly affects the pearl quality.

Q. Where in the world are the most desirable pearls located?

Probably the most desirable and rarest natural pearl will always be the mellow mellow pearl. This is a yellow - golden range commonly found in Myanmar, Burma and Vietnam. The mellow mellow pearl is often hailed as the holy grail of all pearls due to being that of the most value.

The price of a pearl can vary widely in correlation to its size, ranging from $3000 to $65-70,000 at many Gem trade shows, even when such pearls contain blemishes and are therefore still considered imperfect

Q. We often hear about Mikimoto pearls, is this a particular brand or is it a type of organic pearl?

Mikimoto was the first person to commercially produce cultured pearls in Japan in the late 1800’s. Prior to this, cultured pearls had only been produced on an experimental basis but Mikimoto found a technique that he could use to sustainably produce small cultured pearls – typically 7mm - in small saltwater shells.

Its predecessors, being Gem-A, launched the first global Gem lab in London in order to differentiate cultured Mikimoto and natural pearls. The value of each was quite starkly different which meant that many London jewellers became concerned at the introduction of cultured pearls against the trade of more expensive natural pearls. Mikimoto, dating back over 100 years was, and probably still is, the top quality Japanese Akoya pearl on the market.

Q. Being similar in name, what is the key difference between a conch shell and a conch pearl?

Great question! The Conch shell, Lobatus Gigas being its scientific species, occurs only in the Caribbean off the coast of North America, from Florida down through to the West Indies. It is a big shell that was originally gathered by the native people for food due to its very large edible muscle. It is said that 1 in a hundred conch shells could produce a pearl. Conch pearls come in a range of colours from whites to pinks to browns and yellows but it is the pink variety that remains to be the most valuable. We often believe that the very inside of the Conch shell is pink in colour which is why the pink pearl remains the rarest.

However it is also the inside of the conch shell that produces all of the varying colours of conch pearls. Imitations are created when people take the conch shell and try and cut around a bead, passing it off as a genuine pearl. However, these imitations always have concentric bands where, if you look at the side of the bead, you will see what looks like tree ring growth around the edges. This is a kay indication that this is not a real pearl, but an imitation that has been cut out of a shell.

Q. With a huge variety on the market, how do you identify and compare different seashells from one another?

Seashells come in such a wide variety of genus, ranging from freshwater to seawater environments. Dating back to the Victorian times, seashells were and still are highly collectable objects of nature. Linnaeus, founder of the Linnaeus society extensively named over half of the shells we have identified so far. Seashells are very easy to tell the different species apart as they visually look very different from one another.

Today however to differentiate shells via its species level, identification can require DNA analysis to indicate the differences from one shell to the next. They may look very similar but there is stark variation between the different species.

Q. If you’re looking to purchase a high quality shell, what attribute should one be looking for?

People are attracted to different shapes and colour forms with some buying what we call ‘valves’ where two halves of a shell are held together by a muscle, whilst others favour gastropods where the shell is one piece. Some people like to collect a whole family of shells, preferring only to select pieces within the same genus of shells, leading to a lot of variability. Shell prices for collectors range from £2-£3 up to £100,000 for those that are highly desirable.

Q. What are the key differences between 'hard' and 'soft' coral?

A lot of the time when you look at soft corals in its natural habitat under water, they can often look like plants or sea fans which move with the ocean current. They can range in appearance from big broad fans to tall upright branches but most tend to move. Hard coral contains more calcium carbonate than soft and are often what we refer to as coral reef. An expansive garden of skeletons makes up the coral bed where tiny living organisms live within the pores of these hard corals.

Q. Where is Coral found in abundance across the world?

Coral is most commonly found within temperate waters, including the Caribbean, Australia and the Pacific, with its particular type ranging from place to place. Coral will vary widely in habitat from shallow 3-5ft soft coral waters to deep hard coral found over 1000m underwater. The most precious coral for jewellery is the red coral of the Mediterranean, originally found 100ft under water by early fishermen.

This precious coral was thought to be extinct until divers located caves as shallow as 10-12ft containing this red coral species.

Q. So if you’re looking for a piece of jewellery containing red coral, how do you identify it as genuine and not an imitation?

Corals are fairly easy to differentiate with most of the corals – the precious corals – having visible striations that move across the stone/bead. This identifies the growth where the small tree -like structures were with vertical striations of the stems. Many corals are treated with dye to enhance their appearance so being aware of this when purchasing coral is important as those that have been dyed are no longer considered precious. Dyed coral can be identified when a concentrated colour is found along the edges of the stone where the dye has run in a cut stone or if the coral itself is a perfectly uniform colour without imperfection.

Coral value is similar to pearl where the more intense the colour, like red, the more valuable the material is deemed to its pink and orange counterparts.

Q. Final question, I promise! Out of pearl, coral and shell, what is your favourite organic material and why?

That’s a hard one! I have a much more extensive collection of shells since I started collecting them at only 4 years old on the coast which continues till today. In this case, since I’ve been interested for over fifty years, I would probably have to say shells. I collect two main families, the Cowrie shells as well as Conch shells of which The Queen conch is one of them. It was from collecting shells that I got to love pearl, especially as I am yet to find one. The question is tricky as the pearls live inside the shells which then live beside the coral so they are all connected!

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover image of Coral Skeleton and Pearl. All images courtesy of Henry Mesa, Latin American Ambassador at Gem-A.


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


Additional Info

Read more...

Birthstone Guide: Peridot for Those Born in August

Those born in August have vibrant green peridot as their birthstone. Lily Faber FGA DGA EG delves into this zesty gemstone to find out more about its physical properties and fascinating history.

Peridot is the birthstone for August and is known for its rich green colour. It is one of the few gemstones that come in only one colour (green), and its name is thought to derive from the Arabic word ‘faridot’, which translates to ‘gem’. 

Rough Peridot Crystals GemARough peridot crystals. Image by Gem-A.

Peridot is a transparent gem variety of olivine. Coloured by iron, it comes in a range of greens from yellowy-green to brownish-green. It also has a slightly oily or greasy lustre, but don’t let that description put you off!

Read more: What Should Be in the Ideal Gemmologist's Toolkit?

Its distinct olive-green hue is a lovely reminder of long summer days. In fact, some believe that peridot can bring happiness, luck and prosperity while calming anger, conquering fear and protecting one from evil spirits.

Peridot is formed in the Earth’s mantle and makes its way to the surface via volcanic eruptions. It is typically found in ancient lava beds. Occasionally, it can also come from outer space!

Mining for Peridot Gem A Blog August BirthstoneMining for peridot. Image by Gem-A.

A special type of meteorite called a pallasite meteorite sometimes contains peridot within its iron-nickel matrix. If you slice the meteorite open, it will reveal a smattering of transparent to translucent gems.

The History of Peridot

Zabargad Island (St. John’s Island), in the Red Sea off the coast of Egypt, is believed to be the earliest known source for peridot. Centuries ago, the Greeks called this island Topazios, which was also their name for peridot. Later, this island was mined for peridot to fill the coffers of Egyptian kings and anyone who tried to set foot on the island at that time was threatened with death.

It has been said that many of Cleopatra’s emeralds, her favourite gemstone, were actually peridot. Strangely, the ancient Romans called peridot the ‘Evening Emerald’ because they believed that its bright green colour could only be seen at night, which is clearly not the case!

Read more: What is the Link Between an Emerald and the Emerald Cut?

Other localities where peridot is found are Myanmar, Pakistan and the Peridot Mesa in the San Carlos Apache Native American Reservation in Arizona, USA.


Lilypad inclusions. Image by Pat Daly FGA, Gem-A.

The Physical Properties of Peridot

This is a brittle stone with a hardness of 6½, which leaves it vulnerable to chips and scratches. Care should be taken when set in jewellery, especially rings. Perfumes, hairspray and make-up can also damage the stone, so spritz your perfume prior to draping yourself in peridots.

Read more: Questions to Ask When Buying a Piece of Gemstone Jewellery

A characteristic feature that can help differentiate peridot from emeralds is its high birefringence of 0.036, within an RI range of 1.65 to 1.69. As a result, the internal inclusions and facet edges within the stone may appear ‘doubled’ – almost like you are looking at the gemstone with double vision. You can often see this doubling with a loupe or even with the unaided eye if the stone is big enough.

The most prized peridots are those of larger size, with a rich ‘oily’ green colour and few inclusions.


Mica inclusions. Image by Pat Daly FGA, Gem-A.

Peridot Inclusions

Common inclusions are lily pads, which consist of crystals, typically chromite, and are surrounded by curved stress cracks. Mica flakes can sometimes give a brownish tinge to the gem. Needle-like ludwigite inclusions are also seen.


Ludwigite and vonsenite inclusions. Image by Pat Daly FGA, Gem-A.

While this stone has gone in and out of fashion over the years, I encourage you to think of peridot for your next piece of jewellery not only for its gorgeous colour, but also for its interesting and varied history.

Read more: How to Identify Antique Edwardian Jewellery 

Interested in finding out more about gemmology? Sign-up to one of Gem-A's Short Courses or Workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover Image: Peridot © GemA.

Additional Info

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Birthstone Guide: Sapphire for Those Born in September

Legend describes sapphire as a stone of purity, honesty, trust and prosperity, bringing inner peace and protection to its wearer. From a gemmologist’s perspective, sapphire is an important variety of the mineral corundum and an integral part of the global trade in coloured gemstones. Here, we consider the many facets of sapphire, from inclusions and treatments to synthetics, engagement rings and royal connections.

Sapphire: The September Birthstone

Those born in September are lucky enough to count sapphire as their birthstone. This ‘royal’ gem is often described as one of the ‘big three’ – sapphire, ruby and emerald – or perhaps ‘big four’ – sapphire, ruby, emerald and tanzanite’ – in the world of coloured gemstones.

Sapphires have always been prized for their colour and are believed by some to bring their wearer wisdom and truth. Historically they were thought to attract divine favour, prevent the wearer from suffering envy, promote serenity and give one peace of mind. Often used in engagement rings, sapphires are an ancient symbol of fidelity.


Natural sapphire with crystals and feather inclusions.
Image: Pat Daly, © Gem-A.

The word sapphire originates from the Greek word sappheiros, meaning ‘blue stone’. Sapphires are traditionally associated with the colour blue but they can come in any colour aside from red, which would be a ruby. One of the most valuable colours of sapphire is a natural, untreated padparadscha (orangey pink), which means ‘lotus flower’ in Sinhalese.

Sapphire Origins

Sapphires are a variety of the mineral corundum – an aluminium oxide in the trigonal crystal system. These stones are most commonly sourced in Australia, Cambodia, Myanmar (Burma), Sri Lanka, Thailand and in some parts of Africa.

When mined in their natural rough form, sapphires can appear dark and dull until their true colour shines through once polished, cut or treated. The origins of sapphires can directly affect the clarity, carat, cut and colour of the stones and therefore determines their value and popularity to the trade.

Sapphires that are mined within Sri Lanka or Thailand have been considered by many to be the most valuable due to their clarity and brilliance of colour. Like many natural stones, it is the presence of visible inclusions within the crystal structure that can sometimes - but not always - indicate where in the world the sapphire has been mined.


A rough yellow sapphire crystal in bipyramid form.
Image: Pat Daly, ©Gem-A .

Sapphire Resilience

Measuring at nine on the Mohs scale of hardness, sapphire is well known for its good durability and refractive index of 1.76 to 1.78. The resilience of these stones makes them highly desirable not only for the fine jewellery market but also to industry for electronics and scientific instruments.

Due to its high ability to withstand scratching, sapphire is one of the most popular choices for engagement rings and other jewellery pieces for everyday wear.

Sapphire Engagement Rings

Today, sapphire has become the second most popular choice of gemstone after diamond for bridal jewellery and fine jewellery, collections. One of the world’s most famous sapphire jewellery pieces is the blue sapphire and diamond engagement ring given to Lady Diana by Prince Charles in 1981. Prince William proposed with this 18ct oval sapphire ring to his now wife, Kate Middleton, in 2010.

Colour Spectrum of Sapphire

Traditionally, sapphires are thought of as only appearing in naturally vivid blue. In fact, this gemstone can occur in a wide rainbow spectrum of colours; from canary yellow and tropical orange to fuchsia pink. The red variety of corundum is otherwise known as ruby.

Sapphires get their colour from different trace elements. The presence of iron and titanium are responsible for the blue tones, while traces of chromium cause pink tones. Ruby red is a result of more chromium present in a stone’s chemical structure.

Sapphire Clarity and Inclusions

Sapphires can be found as either well-defined crystals or water-worn pebbles, depending on the type of gem deposit. If well-formed, they will take the shape of a hexagonal bipyramid or hexagonal barrel-shape with striations running horizontally across the crystal faces. They are often colour-zoned across the crystal or with hexagonal zoning in their cores.


Sapphire with rutile inclusions that appear as silk. Image: Pat Daly, © Gem-A .

Inclusions are numerous and varied. A few include silk, zircon haloes (circular stress cracks around a zircon crystal), hexagonal and straight colour zoning, feathers (partially healed fractures), negative crystals, two-phase inclusions of a gas and liquid, and fingerprints, which are especially neat feathers.

Read more: Ruby and pink sapphire from Greenland

Generally, the presence of inclusions within a sapphire will make it less valuable, especially if this influences the stone’s overall durability. However in some cases, with Kashmir crystals for instance, the opposite is true. Sapphires sourced in Kashmir, India, often have a very slight milkiness caused by very small inclusions. Colour zoning and stress fractures scatter light to create an almost velvet optical effect without compromising the stone’s transparency. The Kashmir mines are no longer actively mined which adds to the rarity and desirability of this locality.

LocalitiesCommon natural sapphire inclusions
Myanmur
(Burma)

Rutile 'silk', accompanied by pinpoints of rutile. Long needles of apatite; dolomite inclusions (Mogok). Convoluted feathers, silk, hexagonal colour zoning in some stones.

Sri Lanka
(Ceylon)
Crystal inclusions: particularly mica, pyrite and zirca crystals with haloes; healed fractures often resembling fingerprints; rutile 'silk', two-phase inclusions; apatite crystals. Graphite present as solids in two-phase or three-phase inclusions. Elongated negative crystals and pyrite/pyrrhotite are common.
Australia Strong zoning, feldspar, zircon crystals with associated haloes.
Colombia

Crystals of rutile are common.

Table showing common natural sapphire inclusions found in different localities worldwide.
 

Like star rubies, blue and fancy coloured sapphires can display asterism due to silk inclusions. To form a star, corundum needs to have abundant silk inclusions running in three directions at 120 degrees to one another. In order to best display a star, these gems must be cut en-cabochon with the inclusions oriented parallel to the base.

Read more: Exploring Inclusions in a Twelve Point Black Star Sapphire

Light reflects at 90 degrees off of the inclusions to show intersecting, bright bands of light that seem to hover above the surface of the sapphire. Natural star sapphire cabochons are often cut with a slightly rounded base to preserve yield, thereby commanding a higher price.

One of the most famous star sapphires is the greyish-blue Star of India, housed in the American Museum of Natural History in New York. This gemstone is 563 carats and displays a star on both sides, which is atypical.

Read more: The Star of India Sapphire - A Famous Gemstone


An example of a synthetic star sapphire. Image: Pat Daly, © Gem-A .

Sapphire Treatments

Most sapphires on the market today have been heat-treated to improve their colour. These treatments can enhance and deepen a very pale colour or lighten a very dark sapphire.

Another treatment is surface diffusion, which is achieved by heating an already faceted stone in colouring elements, such as iron and titanium, to produce a stronger blue colour that is surface-deep. The stone is then re-polished to sharpen the facet edges. One way to discover this treatment is to place the stone on its table over a diffused white light either directly on the light or immersed in a liquid such as water or baby oil, and to look at the colour concentration.

The location of the colour's presence within the stone can help to determine whether or not it has been treated. For example, if the colour is mainly concentrated at the facet edges and you can see a clear outline of the stone, it has been surface diffusion treated. If the outer edge of the stone fades away and the colour zoning is straight and does not seem to be dictated by its relation to the facet edges, then it has not been surface diffusion treated.

Read more: Understanding the Value of Sapphires

Lead-glass filling is a treatment that can be used to enhance the colour and overall appearance of all varieties of corundum but is more commonly seen in rubies. The lead glass is used to fill surface-reaching cracks and is often an ideal colour such as a saturated red or a vivid dark blue. To detect this treatment, inspect with a loupe to detect fine lines on the surface of the gem (surface-reaching cracks).

Corundum Sapphire Treated Co Glass Filled and Heated GemA PD 0220An example of a lead glass filled sapphire. Image: Pat Daly, © Gem-A.

Look for colour-concentration that is limited to cracks within the stone (a key indicator of this treatment), and if there are bubbles, they will be confined to the glass in the cracks. A red flash may be seen in the glass filling.

Natural Sapphires vs. Synthetic Sapphires

Whilst synthetic stones display an almost identical chemical composition to natural corundum, uncut synthetic specimens can often exhibit a variety of different crystal habits. One of the ways to separate synthetic and natural sapphires is by their characteristic inclusions.

The most common type of synthetic corundum is Verneuil flame-fusion. Verneuil flame-fusion sapphire forms as a boule which is shaped like a bottle. Faceted verneuil flame-fusion sapphires commonly display curved colour zones which are present due to the formation of the rounded boule.

 An example of Verneuil flame-fusion in synthetic corundum, which forms as a boule. Image © Gem-A.

These curved growth zones can be detected with both a loupe and a microscope depending on the size of the stone and the visible depth of colour saturation. Elongated gas bubbles as well as induced 'fire marks' caused by the polishing process may also be seen on the surfaces of the facets. These ‘fire marks’ are typical of corundum polished without sufficient care and are an indication, but not irrefutable proof, that the stone is synthetic.

Additionally, you can use the diffraction grating or prism spectroscope to detect synthetic Verneuil flame-fusion blue sapphires. Whilst many natural blue sapphires show an absorption spectrum of between 1, 2 or 3 black bands that appear in the blue, Verneuil flame-fusion blue sapphires do not show a spectrum whatsoever.

Sapphire Care and Caution

Sapphires have a hardness of 9 on the Mohs scale of hardness, and their ability to resist scratching and wear while taking a bright vitreous polish, not to mention their irrefutable beauty, makes them ideal for everyday wear. For good practice, do not put these gemstones in ultrasonic cleaners and be careful when setting them as they can chip or fracture.

Heat treatments are relatively stable and will not affect the stone’s ability to be cleaned. However, if a sapphire is filled with cobalt-coloured lead glass, that is a totally different story and care must be taken when the stone is cleaned and also when it is taken to a jeweller for setting or jewellery repair. It is crucial that you are aware of this type of treatment as lead glass has a lower melting point than sapphire and will leak out of the stone should it be heated by a jeweller’s torch.

Start your gemmology journey with our range of Short Courses and Workshops.

Find out more about the Gem-A Gemmology Foundation course here, or speak to our Education department via education@gem-a.com

Cover image: Synthetic sapphire showing seed crystal inclusions. Image: Pat Daly, © Gem-A.

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Turkish Designer Özlem Tuna Named Gem-A’s Gem Empathy Award Winner at IJL 2017

Gem-A is excited to announce that Turkish jewellery designer and International Jewellery London (IJL) Design Gallery exhibitor, Özlem Tuna, has won the 2017 Gem Empathy Award with her 'Dance of Branches' ring.

This year, IJL exhibitors from across the globe were tasked with creating a hand-drawn or CAD rendered design based around a beautiful, fancy-cut gemstone sourced from award-winning gem-cutter, John Dyer.

Finalists in the 2017 Gem Empathy design competition in partnership with International Jewellery London 

The Gem Empathy judging panel, made up of Gem-A CEO Alan Hart, IJL Event Director, Sam Willoughby, Gem-A Chairman Maggie Campbell Pedersen, and guest judge Liza Urla of jewellery platform GEMOLOGUE, was tasked with selecting a design that uses the 4.14 carat zig-zag green tourmaline in the most innovative and captivating way.

Despite stiff competition from a number of emerging designer-makers and brands, Özlem Tuna of Özlem Tuna Design was unanimously selected as the winner of the competition for her 'Dance of Branches' ring.

The sculptural piece was inspired by nature and features two curved bands in either 18k green or white gold, designed to look like the branches of trees moving in the wind. These bands of gold meet at the green tourmaline gemstone, which appears to float above the surface of the precious metal like leaves on a tree.

Dance of Branches ring by Özlem Tuna

Judges praised the design for its architectural, yet fluid shape and the prominence afforded to John Dyer’s striking fancy-cut gemstone.

Gem-A CEO Alan Hart commented: "I was instantly attracted to Özlem Tuna’s design, which not only showcases John Dyer’s eye-catching zig-zag cut tourmaline to great effect, but also offers a contemporary, sculptural aesthetic reminiscent of a work of art. We are pleased to continue the tradition of Gem-A’s Gem Empathy Award at IJL, and we look forward to seeing the ‘Dance of Branches’ ring come to life very soon."

Özlem Tuna Design advocates sustainable design and cultural preservation through its contemporary jewellery and homeware collections, which have been designed, produced and sold in the Historical Peninsula area of Istanbul since 2003.John Dyer's zig-zag cut tourmaline, presented to Özlem Tuna Design at IJL 2017

Commenting upon the winning design, Brand Manager at Özlem Tuna Design, Fatos Burcoglu said: "It is my honour to work with a Turkish jewellery design who has now won the 2017 Gem Empathy Award. This accolade highlights the success of Turkish designers. Now, our aim is to continue to showcase the existence of Turkish designers across the world and encourage their proliferation and success."

The Özlem Tuna Design team was presented with the 2017 Gem Empathy Award and the striking green tourmaline gemstone at IJL on Tuesday, September 5. The brand will now bring its winning design to life and the final piece will be unveiled at a future Gem-A event.

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership

Main image from L-R: IJL marketing manager, Leigh Martinez, Gem-A CEO, Alan Hart and Gem Empathy Award winner, Özlem Tuna. 


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

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Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

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Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

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Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

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Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

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Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

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Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

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Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

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Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

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Additional Info

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Ancient Sapphires and Adventures in Ceylon

Helen Molesworth FGA, managing director of the Gübelin Academy and a professor of the history of jewellery, takes the reader back in time to Seilam, now Sri Lanka.

'From here...we reach the island of Seilam, which is, for its size, one of the finest islands in the world...This island produces many precious gems, amongst which are rubies, sapphires, topazes and amethysts. The King of the island owns a ruby thought to be the most beautiful in the world, as long as the palm of your hand and as thick as three fingers; it shines like the most burning fire and is perfect.' - Livres des Merveilles du Monde or Book of Marvels of the World, Marco Polo, ca 1300

At the age of 17, a young merchant from a Venetian family set off with his father and uncle on an unusual expedition: to travel and explore the Far East. Twenty-four years later, in 1295, they returned to Venice, wealthy men, with a valuable hoard of both stones and stories. Immediately caught up in the Italian war to which they had returned, Marco Polo was imprisoned, and before his release, dictated his travels to a fellow inmate of posterity. What is passed down to us is a wonderful medieval European account of parts of Asia and the Middle East, from a unique historical perspective. Although relatively brief, the account of Sri Lanka, here Seilam, is extremely appropriate. It is an excellent early reference not only to the first known source of ruby (and maybe also and/or spinel, which was often confused in early sources) and sapphire at the time, but also to the beauty of the island.


A roman sapphire cameo, almost certainly from Sri Lanka, depicting Aphrodite feeding an eagle, first century. Image courtesy of the Fitzwillian Museum, Cambridge.

Known by the Greeks and Romans as Tabropane, in Persian as Serendib, and to be recognised more recently under British rule as Ceylon, Sri Lanka was often referred to by writers as a utopian land of natural riches and great beauty. The earliest gem reference to the island was as the origin for the valuable gems given by Middle Eastern King Solomon to the Queen of Sheba in the Old Testament. Centuries later, not far away in ancient Iraq, a wonderful oral tradition of fabulous story-telling developed in the Thousand and One Nights, in which we find the fantastic tales of continuous castaway Sinbad the Sailor, whose sixth voyage saw him shipwrecked on the very same island, where rivers flowed with rubies, diamond, pearls and 'many precious things'. From a western perspective, Sri Lanka's natural resources were already being traded into Europe through India by the time of Alexander the Great in the third century BC, thanks to the development of the Silk Route. By the time of Marco Polo's Livres des Merveilles du Monde, this fine island paradise was already clearly recognisable as an 'Island of Gems': the Ratna Dweepa of ancient Sanskirt.

A roman gold ring mounted with a sapphire, Sri Lankan, circa third century AD, Babar-Content Collection of Ruby, Sapphire and Spinel. Image courtesy of Medusa-art.com

All the more amazing are such early geographically-relevant accounts of sapphire when we realise that many seemingly ancient references to corundum are mistranslations or transliteration errors. Traditionally, European scholars have substituted our word (and European variations of) 'sapphire' for the ancient Latinised Greek or Persian versions of sapphirus, discarding modern day mineralogy in their translation efforts. In the majority of early references, such sapphirus would have been the blue lapis lazuli from the ancient mines of Afghanistan, and at worst case, any blue stone in general. The poor ruby suffers even worse the woes of inaccurate reporting. Often credited by non-historians today with being one of the Old Testament gemstones mounted in the High Priest's breastplate in the book of Exodus together with other marvellous ancient ruby references, in fact we have little to no archaeological evidence supporting the use of ruby as a gem so far back. Other red gems such as garnet, spinel, maybe; ruby, sadly not.

This highlights the importance of archaeological evidence supporting ancient references, and happily in the case of sapphire, a handful of important sapphires survive from antiquity. Several known Roman jewels exist, perhaps set in a ring with a single 'cabochon' polished pebble, such as the third century example from the Babar-Content Collection; and a few more tend to appear with other multi-coloured gems in later Byzantine jewels. Arguably one of the earliest and most beautiful is the Roman sapphire drilled as a bead and carved in cameo depicting Aphrodite feeding an eagle, a subject of imperial allegory from the first century and now in the Fitzwilliam Museum in Cambridge: an extraordinary important object, which would have been in the most prestigious of ancient collections.


The spoils of river mining in Sri Lanka: a collection of water worn sapphire pebbles.

By the Middle Ages onwards, naturally more sapphires survive, and unsurprisingly the best are found in royal collections. Two spectacular sapphires sit in the Imperial Crown of Great Britain: the seventeenth century Stuart Sapphire and the eleventh century St Edward's Sapphire, the oldest gem in the Royal Collection. Under Queen Victoria, both astonishing stones took pride of place at the front and atop the Imperial Crown. The huge hundred carat Stuart Sapphire sat central to the circlet, until it was bumped to the back by the Cullinan II in 1909, while the smaller St Edward's sapphire, eponymously and originally belonging to Edward the Confessor, remains in its venerated position, befitting its earliest owner, in the surmounting Maltese Cross.


Helen Molesworth trying out traditional faceting and polishing techniques with a bow drill in Sri Lanka. Image by Armil Sammoon.

Perhaps the most remarkable early medieval sapphires, however, were those mounted in the early ninth century Carolingian amulet known as the Talisman of Charlemagne. Said to have been sent to the Holy Roman Emperor by the Middle Eastern Abbasid Caliph Harould Al-Rashid, two sizeable sapphires once sandwiched a hair of the virgin as combined powerful symbols of purity, loyalty, royalty and righteousness. Exemplary too, of our Silk Route road for sapphire travels. These, and all those preceding, were almost undoubtedly examples of Sri Lankan sapphires, as Sri Lanka was, crucially, our only known source of sapphire in the ancient world.

I was fortunate enough to visit this incredible country recently, and to experience production and trade first hand on this 'Island of Gems'. Sapphires are still central, psychologically and financially, with a host of other gems, including garnet, moonstone, quartzes and spinel featuring frequently in local mining and manufacturing. I experienced main mining techniques directly, plus post production, in the regions surrounding Ratnapura, our traditional 'City of Gems', and from a historical perspective, it was remarkable to see hundreds, if not thousands, of years' practices continuing today as if through unbroken tradition.


Local miner with gem finds, Sri Lanka.

River panning for alluvial deposits continues almost unchanged, a millennial old mining practice which sorts surface-reachable deposits with relative ease. I descended shaft mines, also after secondary placers and another age old mining technique, which would have developed naturally after easier alluvial river beds would have been worked out. Watching the traditional blow-pipe heat-treatment of ruby buried amongst coke and coconut shell in a back yard reminded me of two medieval Arabic accounts - of Middle Eastern polymaths Al-Biruni and Teifashi - of burying Sri Lankan rubies within or under bonfires to improve their colour. Even some of the local cutting and polishing practices, with original hand-held bow drills, followed almost the exact same mechanism as a gem-carving drill depicted on one Mediterranean Roman gem-engraver's tomb from the first century AD.


Traditional heat treatment with blow-pipe and charcoal, Sri Lanka.

Yet Sri Lanka has balanced tradition with continual development. While quality of production and some traditional techniques have remained consistent for thousands of years, cutting-edge technologies have been developed and international trade drawn in from all over the world. At the same time as remaining a player on the world stage of gem production, Sri Lanka has successfully held off the loom of large scale mining giants ready to reap the riches of this tiny island below the surface, a forward-thinking decision in favour of local sustainable practices to give the country and its people a long term future.

This compact but competent land, long considered a natural utopia to travellers and traders, and once more coming into its own in terms of tourism, has consistently remained a true Island of Gems, a centre for sapphires, and indeed one of the 'finest islands in the world'.

Gem-A members can log in to read the full article Gems&Jewellery Autumn 2017 / Volume 26 / No. 3

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops.

If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover image: Sapphire crystals from Sri Lanka. All images ©Helen Molesworth, unless otherwise stated.


The Fascinating History of Antique Turquoise Jewellery

The Fascinating History of Antique Turquoise Jewellery

In his third Gemstone Conversations column for Gems&Jewellery, Jewellery Historian and Valuer John Benjamin FGA DGA FIRV explores the fascinating history of turquoise and its use in jewellery design from the Shahs of Persia to the Art Deco design movement.

Read more


Birthstone Guide: Garnet For Those Born In January

Birthstone Guide: Garnet For Those Born In January

If you're lucky enough to be born in January, vibrant garnet is your birthstone. A rainbow jewel of the gem world, garnet displays the greatest variety of colour of any mineral and is very often untreated, making it a rarity in the gem world. 

Read more


Getting Started with Quartz Inclusions

Getting Started with Quartz Inclusions

Do you know your calcite inclusions from your dumortierite, epidote, fluorite and rutile? Here, Charles Bexfield FGA DGA EG explores some incredible quartz inclusions and explains what to look for when shopping for quartz specimens.

Read more


Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Understanding Iridescence: Opals, Pearls, Moonstones and Fractured Stones

Iridescence has to be one of the most mesmerising and magical optical effects seen in gemstones. But have you ever wondered how it occurs? Gem-A's Collection Curator Barbara Kolator FGA DGA shines a light on this fascinating optical effect and tells us about the gems that are most likely to display it.

Read more


Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Hidden Treasures: Highlights of Gem-A's Gemstones and Minerals Collection

Gem-A Gemmology Tutor Pat Daly FGA DGA offers us a glimpse at some of the more unusual items in Gem-A's Gemstones and Minerals Collection.

Read more


Tanzanite: The Contemporary December Birthstone

Tanzanite: The Contemporary December Birthstone

Are you looking for the perfect festive gift for a December baby? Gem-A tutor Lily Faber FGA DGA EG considers tanzanite – one of three birthstones for December – and shares how this relatively new gemstone compares to its purple and blue-hued rivals.

Read more


Birthstone Guide: Turquoise For Those Born In December

Birthstone Guide: Turquoise For Those Born In December

Beautiful blue turquoise is one of three birthstones for the month of December (in addition to zircon and tanzanite). It is enriched with real cultural significance that can be traced back thousands of years. Here, we explore the blue shades of turquoise and explain what makes this gemstone so special...

Read more


Understanding the Cat's Eye Effect in Gemstones

Understanding the Cat's Eye Effect in Gemstones

Chatoyancy is the gemmological name given to the curious optical effect in which a band of light is reflected in cabochon-cut gemstones, creating an appearance similar to light bouncing off a cat's eye. Gem-A's Collection Curator, Barbara Kolator FGA DGA explains chatoyancy and highlights some of the many gems in which it can occur.

Read more


Jade and its Importance in China

Jade and its Importance in China

Jade has long been revered by gem lovers internationally, but nowhere more so than in China. But what is it that makes this gemstone so special? Gem-A's Assistant Gemmology Tutor Dr Juliette Hibou FGA gives us an overview of jade, how to identify it and its significance in Chinese culture.

Read more


Highlights of Gem-A Conference 2019

Highlights of Gem-A Conference 2019

The Gem-A Conference is always the highlight of our gemmological calendar! If you didn’t manage to make it, we’ve put together a few of the highlights from this year’s event to fill you in on what you missed, and whet your appetite for Gem-A Conference 2020!

Read more


 

Additional Info

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Discovering Agates on the Shores of Cornwall, England

Cally Oldershaw FGA DGA describes the thrill of finding agate on the shores of Cornwall and reveals how these subtly-toned gemstones are shaping her jewellery collections in collaboration with geologist and lapidarist, Ben Church.

With many more people choosing to stay in the UK for their 'staycations' rather than going abroad for the holidays, the numbers visiting popular tourist regions such as Cornwall is increasing.

Agates of Cornwall

Of the Cornish rocks and the many millions of pebbles on the beaches, only a few are true agates showing the characteristic banding that defines them. The process of looking for agates is simply to visit a beach and walk slowly, looking at as many pebbles as possible. Determining whether a pebble is an agate is more of a challenge, it takes time and experience to identify the agates and from those, the ones that will be best suited to be made into jewellery.


A selection of Cornish cabochons and slices from Cally's jewellery collections.

Time and location are also important. The best time to look for the agates is when the tide is going out, as the banding in the agates shows better when they are wet; searching the intertidal areas from the high tide 'strand line' is likely to be most successful. Some beaches yield more agates than others and this changes with the tides and the seasons as the amount of sand and pebbles on each beach fluctuates, sometimes daily, throughout the year. It took us almost two years of researching and visiting potential collecting sites to develop an effective method of finding Cornish agates.

What is Agate?

Agates are a type of quartz, the same family as colourless rock crystal, purple amethyst, grey to brownish-grey smoky quartz, black morion and yellow citrine crystals. Cornish agate consists of banded varieties of chalcedony and many occasionally include areas of crystalline amethyst, rock crystal or morion. Chalcedony is defined as microcrystalline or cryptocrystalline (hidden crystals) quartz, where crystals are too small to be seen without using a microscope.

No two agates are alike; each is formed over millions of years and has its own unique colours and patterns. Their distinctive colours include grey, cream, caramel, white, colourless chalcedony. Some pieces have translucent or transparent bands, where it is possible see through the agate.

Left: A model wearing a pendant made of Cornish agate. Right: A Sculptural piece approx. 10cm across with purple crystalline amethyst

The Cornish agate pebbles and polished pebbles have been used in crystal therapies. Named for their colours; the more vibrant poldark agate and Cornish caramel agate, are believed to help energise, while the cooler colour of Cornish grey agate and Cornish cream agate have a calming effect. A reddish coloured blush agate is particularly rare.

Cornish Agate Formation

Most agates have a volcanic origin, with the agate filling cavities or vesicles (small bubbles) within volcanic igneous rocks. Cornish agates formed about 240 million years ago and have a different origin. The characteristic granite landscape of the Southwest of England including Dartmoor, Exmoor, and Bodmin Moor, as well as the Scilly Isles, are all part of a large intrusion of igneous rock, which slowly cooled between 1.5 and 3 miles underground, causing fissures and cracks in the surrounding rocks (country rocks).

Cornish agates formed from got silica-rich fluids that filled these cracks and fissures called veins (like the veins within a leaf) within the country rocks, and then cooled and solidified to form vein agate.


Another selection of Cornish agate jewellery in a variety of colours.

The country rocks surrounding the granite were folded and faulted as the sea floor between Cornwall and Europe was compressed, and the rocks buckled up to form the landscapes and coastal cliffs of Cornwall. Over millions of years, these folded and faulted rocks were weathered and eroded. In rare cases, the veins can be seen in the rock faces and cliffs at the back of beaches. As the rock was broken down, agates were released to the beaches, where the energy of the seas moved the agate back and forth with the tides, gradually grinding sharp angular rock fragments into smooth rounded pebbles.

Cornish Agate Jewellery

Having collected and sorted the agates, the first step in making the jewellery is to make a slice to check the pattern within. Ben [Church] uses a saw with a 25cm diameter diamond blade, which cuts about 10cm an hour. The blade is lubricated and cooled with honing oil that gives a smooth satin surface and is wonderfully tactile. It can take several hours to prepare and make the first cut through one of the larger pebbles.

We assess each slice individually, inspired by the unique pattern of each agate, to decide whether to trim and polish a slice as an irregular shape (freedom form), or draw around set templates to produce oval and teardrop shapes for example. We then sort the slices to choose which will be made into cabochons, with a rounded upper surface, and which will be worked as polished, flat slices.

Left: Cally collecting Cornish agates. Right: Cornish grey agate slice on chord.

Initially the flat slices were made into freedom forms with a drilled hole so that agate slice could be worn on a leather cord. A later development was a surf board design with further accentuated the Cornish essence of the agate, fitting with the Cornish beach and surfing lifestyle.

Adding a sterling silver pinch ball and chain was the next development phase. This jewellery has Made in Cornwall accreditation, as we collect the Cornish agates from the north coast of Cornwall, as well as cutting, slicing, polishing, drilling and packaging the jewellery all within about 10 miles of where they have been found. Pieces have been exhibited at Made in Cornwall events and displayed in the Lander Gallery in Truro, Cornwall.

This year we also had some of the agates mounted in sterling silver bezels and displayed on sterling silver necklaces to enhance the natural beauty of the agates, whilst placing the agate in the content of fine jewellery.

The Infinite Wave Jewellery Collection

The latest range of jewellery is our Infinite Wave Cornish Agate Collection. We have used the waves of the Cornish coastline as our inspiration to design unique luxury pieces.


Left: Cornish caramel and Cornish cream agate polished pebble
. Right: A model wears jewellery design featuring Cornish agate

Having worked with gemstones and with the jewellery industry for more than 30 years, it has been a wonderful challenge and an exciting experience to bring together my love of gemstones and jewellery to design something so uniquely Cornish.

My vision for jewellery, as a consultant in sustainable mining and ethically sourced gemstones, is to design a collection that, in collaboration with jewellers' worldwide, would be produced using only Fair-mined and Fairtrade gold and platinum, and ethically sourced silver.

Find out more at cornishagates.co.uk

This article originally appeared in the Winter 2017 (Vol. 26 No.4) issue of Gems&Jewellery magazine

Interested in finding out more about gemmology? Sign-up to one of Gem-A's courses or workshops. If you would like to subscribe to Gems&Jewellery and The Journal of Gemmology please visit Membership.

Cover image: Cornish grey agate slice © Ben Church. All images © Ben Church.


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The RealReal, the leading authenticated luxury consignment company, today announced a first-of-its-kind collaboration with the University of Arizona to create a new degree program for gemology. The RealReal is funding an endowed chair in the UA College of Science with the intent of helping the University of Arizona develop new research and technology. An undergraduate program will be offered, along with a graduate program for master's and PhD students emphasizing gemological research and skills will be made possible through this endowment. Finally, Gem-A (Gemological Association of Great Britain) is also partnering with the UA and The RealReal to allow students in the program to obtain their individual gemology certification.

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The new degree program will be located in Tucson, Arizona, the mineral and colored stone capital of the world. Students will learn on campus and in state-of-the-art labs located in the University of Arizona's new Gem and Mineral Museum in downtown Tucson.

"As the market leader in the jewelry resale market, we have always invested heavily in gemologists, research, and technology," said The RealReal CEO Julie Wainwright. "Collaborating with University of Arizona on this new degree program will enhance our efforts and the entire industry. We have had great success working with University of Arizona gemologists in the past and are extremely impressed with their expertise. We are excited to share their knowledge with the world."

"The RealReal is clearly an innovator in the luxury space. The University of Arizona is a known innovator in many aspects of retail, forensic sciences, and development of novel programs.  I am thrilled that these two entities who are currently leading in their respective fields are now working together to build this gemology program. These partnerships are how transformative changes happen." - Joaquin Ruiz, Dean, UA College of Science; UA Vice President for Innovation; Executive Dean of the Colleges of Letters, Arts and Sciences

About The RealReal

The RealReal is the leader in authenticated luxury consignment. With an expert behind every item, we ensure everything we sell is 100% real. We have 60+ in-house gemologists, horologists and brand authenticators who inspect thousands of items available online each day. As a sustainable company, we give new life to pieces by brands from Chanel to Cartier, and hundreds more, supporting the circular economy. We make consigning effortless with free in-home pickup, drop-off service and direct shipping. At our store in SoHo NYC customers can shop and consign and meet with our experts to learn more about luxury authenticity and sustainability. In eight Luxury Consignment Offices across the country, our expert staff provides free jewelry, watch and handbag valuations.

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