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.

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Rio Tinto Reveals The 2.11ct Argyle Everglow Red Diamond

It is always an exciting time of year when Rio Tinto unveils what has been discovered at its Argyle diamond mine. Typically, this is beautiful pink diamonds, with the occasional purplish violet tones. Even rarer still are the fancy red diamonds, which remain a mysterious quantity even today. 

It is without doubt that red diamonds are some of the most beautiful and captivating gemstones, largely due to their extreme rarity. In fact, it has been estimated that as few as 30% of all red diamonds have been discovered, leaving many curious to what showstoppers remain untouched below the surface.

The colour red is thought to symbolise love, passion and strength, which makes red diamonds an especially meaningful shade for collectors with significant funds. Those with an eye on the market will undoubtedly have spotted The Argyle Everglow - a 2.11 carat polished radiant-cut diamond presented as part of the 2017 Argyle Pink Diamonds Tender. 

Read more: The World's Most Expensive Diamond at Auction.

The Argyle Everglow was immediately identified for its miraculous size, colour and clarity and, after being assessed by the Gemological Institute of America (GIA), it has been given a grade of Fancy Red VS2.

Just to put the significance of this into perspective, in the 22-year history of the Argyle Pink Diamonds Tender, there have been less than 20 carats of fancy red certified diamonds sold.  

Argyle Everglow 2.11 carat radiant shaped Fancy Red. Image by Rio Tinto.

The 2017 Argyle Pink Diamonds Tender, also named 'Custodians of Rare Beauty' will present 58 diamonds with a total carat weight of 49.39 carats, including four fancy red diamonds, four purplish red diamonds, two violet diamonds, and one blue diamond.

The five 'hero' diamonds in the collection are as follows:

  • The Argyle Everglow, 2.11 carat radiant shaped fancy red diamond
  • The Argyle Isla, 1.14 carat radiant shaped fancy red diamond
  • The Argyle Avaline, 2.42 carat cushion shaped fancy purple-pink diamond
  • The Argyle Kalina, 1.50 carat oval shaped fancy deep pink diamond
  • Argyle Liberté, 0.91 carat radiant shaped fancy deep grey-violet diamond

 

Argyle Avaline 2.42 carat cushion shaped fancy purple pink. Image by Rio Tinto.

Read more: 'Diamonds: Rare Brilliance' Showcase Collection.

Found primarily in Australia, Africa and Brazil, red diamonds are so rare that only 20 to 30 stones are officially known to exist with each one measuring less than half a carat on average.

Argyle Liberte 0.91 carat radiant shaped fancy deep gray violet. Image by Rio Tinto.

Argyle Kalina 1.50 carat oval shaped fancy deep pink. Image by Rio Tinto.

In light of the reveal of The Argyle Everglow, we hit the archives to recall the most spectacular discoveries of red diamonds that have captured the interest of high-end jewellers, aficionados and collectors worldwide...

The Hancock Red Diamond

Whilst this round brilliant-cut diamond is not famous for its size, weighing in at 0.95ct, it is praised for its astounding deep red and purple colours, making it one of the most highly sought-after stones to date.

The Kazanjian Red

With a history nearly as big as its size, this South African diamond, although later cut in the Netherlands, was found over 100 years ago weighing in at 5.05 carats from the original rough 35ct stone. In 2010, the Kazanjian red diamond was on display in the Morgan Memorial Hall of Gems at the American Museum of Natural History before being purchased by Kazanjian Bros. Inc.

The Moussaieff Red Diamond

Discovered by a Brazilian farmer in the 1990s, the Moussaieff Red, otherwise known as 'Red Shield' is an internally flawless, triangular brilliant-cut fancy diamond famous for its 5.11 carat weight. This iconic diamond remains one of the largest red diamond discoveries in the world to date.

The Edcora Red

This pear-cut fancy red brown diamond, weighing in at 5.71 carats is known as the 'lost stone' due to vanishing from the public eye into the collection of a private investor. Whilst there have been no identified photographs of this red diamond, its existence has been well-documented in writing.

The DeYoung Red Diamond

The DeYoung red diamond is a rare 5.03 carat unmounted diamond purchased by a Boston jewellery seller at a flea market. Sydney DeYoung initially mistook the stone for a garnet but, upon noticing its high quality, had it laboratory tested to reveal its true identity as a red diamond. After his death in 1986, the DeYoung red diamond was given to the Smithsonian Institution’s Natural Gem and Mineral Collection where it remains on public display.   

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 2017 Argyle Pink Diamonds Tender hero diamonds from Rio Tintos Argyle Diamond mine. ©Rio Tinto.


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.

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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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Fossicking in the Outback

Carmen Garcia-Carballido FGA DGA L.Geology MSc. EurGeol travelled to the southern hemisphere to find out more about the opals and sapphires of eastern Australia.

To test the skills acquired in two years training as a gemmologist with Gem-A, my husband planned a three week field trip to the sapphire and opal fields of eastern Australia.

We flew from Aberdeen to Sydney, hired a motorhome and headed into the outback of New South Wales (NSW) and Queensland. However, cyclone Debbie making landfall on the coast put paid to our plan to visit a gem dealer in Yepoon and check out the Marlborough Chrysoprase. To keep safe we stayed inland, driving 4,500 km in 13 days and camping at a different site every night.

Map of Australia showing key sapphire and opal locations and the field trip itinery. Image by Peter Scott-Wilson.

Two days from Sydney, our first gem field was Glenn Innes where we tried fossicking for the first time. A petrol station sold us a ‘bucket of dirt’ and rented sieves for AUS $20. Washing the dirt off, we found our first sapphires and zircons. We admired Robert Cook's collection of locally mined parti-colour sapphires that he cuts in his shop at the Visitor Information Centre. After some purchases, my husband had to drag me out of Robert’s shop.

60 km west at Inverell, we met Jack Wilson, who owns a longstanding sapphire mine and his wife Dallas, who designs lovely jewellery with blue sapphires from his mine. I bought some untreated rough blue sapphires with the idea of learning to cut them myself. Jack explained the host rock (i.e. the primary deposit where the sapphires formed) has not been identified. These sapphires are found in secondary, alluvial deposits.


Rough untreated sapphires from Jack Wilson's mine. L-R 10.21 ct and 6.54 ct.

After a long drive west, roads littered with dead kangaroos took us to Lightening Ridge, famous for its black opals. The town in the desert appeared empty. Tourists do not arrive until Easter. Only emus stay all year round. We camped in a site by the artesian baths, a wonderful way to relax and learn about the immense subterranean artesian system that probably played a role in the development of the opal fields. We visited an underground opal mine and were allowed to fossick for opals on the ‘mullock heaps’ of old spoil outside the mine. My husband found a small sample but I was not so lucky.

Next day we headed northwards. I was disappointed I could not buy any black opals in Lightning Ridge because the shops were shut, but a few kilometres before crossing into Queensland, a roadside sign led to the house, shop and workshop of Greg Armstrong. An opal miner, cutter and stone setter. Greg laid out his collection of white and black opal (3) and when we mentioned we were learning lapidary, he gave us a bag of ‘potch’ opal to practice cutting at home.

Boulder opals from Quilpie, mined and cut by Eddie Lunney.

Over the state boundary, we headed north for St. George, Roma, where the oil and gas industry’s mega coal bed methane (CBM) project produces gas from extensive Permian and Jurassic coal deposits to supply the energy needs of c. 90% of the homes in Queensland, and the location of the famous Carnarvon Gorge.

We drove inland to central Queensland to The Gemfields area, which includes the localities of Anakie, Rubyvale, Sapphire and Emerald, where green gemstones initially taken for emeralds were found in about 1880, when drilling for water, ahead of railway construction. Green and yellow sapphires and zircons have been mined in this area since the 1880s.

Read more: Field Trip: The 'Emerald Desert' in Western Australia

At the Sapphire Caravan Park we watched wallabies and lorikeets being fed. Taking Jack Wilson’s advice, we looked for Peter and Eileen Brown at the Rubyvale Gem Gallery, but as they were on holiday, the shop manager showed us Peter’s amazing fancy cuts on parti-colour sapphires. The shop is a gemmologist's paradise. Alicia Pray was cutting beautiful black star sapphire cabochons from the Desperado mine, and we bought a bag of ‘wash’ from the mine to fossick back home in Scotland.


Coloured sapphires collected over a period of 40 years in The Gemfields of Queensland by Peter Brown of the Rubyvale Gem Gallery.

Alan, a lively Stranraer émigré, took us round an underground sapphire mine in Rubyvale. Prospectors first dug one metre diameter vertical shafts through ‘shin cracker’ overburden (sandy gravels). The bottom layer of wash sits uncomfortably over eroded granite. When miners hit the granite at a depth of 15 m or so, they dug horizontal tunnels to follow the alluvial pay zone where sapphires, zircons, garnets and occasionally diamonds concentrate. Miners knew if they found a block of quartz in the wash, and sapphires were present, they were likely to aggregate upstream of such ‘Billy boulders’. This helped them to orientate their tunnels.

Geological section c.15m below the surface inside the Walk-in Miners Heritage Sapphire Mine at Rubyvale. The alluvial sapphires concentrate within narrow 'wash zones' (average 15-20 cm as marked by dotted lines) above the 'granite floor' and below several metres of sandy alluvial gravels. Elongated features are pickaxe marks.

From The Gemfields in Queensland, we drove westwards to Barcaldine ahead of cyclone Debbie's rainclouds. Here we decided to head south towards the Quilpie opal fields. As the land became more arid, the soil turned red, the gum trees thinned out and the grass grew sparse. Intrepid wildlife competed with massive ‘road trains’ for the driver’s attention on the empty roads between the gem locations. We passed trucks hauling three trailers, sometimes four.

Arriving in Quilpie, everywhere we went we were presented with useful information, friendly advice and ideas for things to see, and a chance to cool down from the 35 °C heat of early autumn in the outback. In Quilpie, they told us St. Finbarr’s Catholic Church was worth a look. Its altar, font and lectern have impressive panels of boulder opal donated in 1976 by local miner Des Burton, the father of the boulder opal industry. I was quite literally on my knees in adoration.

The only shop open in Quilpie sells everything. There I found the last copy of Greg Pardey’s Black Opal: A Comprehensive Guide to Cutting on its shelves and read it cover to cover before we got back to the UK. Walking back to the motorhome on our way out of town, we noticed that the Opal Hunter shop had opened too. Asking if I could buy some rough opal to cut back home, shop owner Eddy Lunney told me he would need to get to know me before knowing what he wanted to sell me. Induction into opal heaven started with a tour of the shop, the lapidary workshop and the yard with part of his huge stock of boulders from his opal mine. By teatime he had given me a masterclass in boulder opal cutting and polishing. I absolutely loved it! The dark blue and purple colours he brings out of the transparent opal (known as crystal) are gorgeous. It was really hard to leave Quilpie the next morning.

We noticed a change in the weather. The temperature had dropped to 20 °C as we drove to Yowah. In this famous opal location, we found Scott Shorten, shopkeeper, opal mine tour guide and librarian. After lunch, with his shopkeeper hat on, he showed us round the Yowah Opal Centre. Yowah opal is found inside nodules. Nine out of ten nodules are empty, so it is always exciting to crack open one, using a hammer or even better sawing through it, to see whether there is any opal inside. Scott sold us some good samples.

Before flying home, Matthew Morin FGA FCGmA senior sales consultant at Altmann + Cherny, a jewellers on Sydney’s Pitt Street, showed me how beautiful opals are used in modern jewellery (6). The shop also hosts The Olympic Australis, the largest and most valuable piece of opal ever found. It is a white opal from Coober Pedy, which weighs 17,000 ct, measuring 28 cm long by 11.5 cm high. For more information visit altmanncherny.com.au/famous

ACKNOWLEDGMENTS Carmen Garcia-Carballido would like to thank her husband, Peter Scott-Wilson, for organising the wonderful tour. Eddy and Lynda Lunney for their hospitality at Quilpie. Jack and Dallas Wilson, Robert Cook, Greg Armstrong, Scott Shorten, the staff at Rubyvale Gem Gallery and Matthew Morin for generously giving their time to discuss Australian gemstones.

Carmen meeting Matthew Morin at Sydney jewellers Altman + Cherny. Matthew is also the president of, and a gemmology tutor at the NSW division of the GAA (The Gemmological Association of Australia). Carmen is modelling a Koroit boulder opal pendant on white gold from the shop. Image by Peter Scott-Wilson.


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 Yowah boulder opals cut by Scott Shorten. Image by Carmen Garcia-Carballido.


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 Separate Natural from Synthetic Ametrine using Conventional Equipment

Guy Lalous ACAM EG summarises the discovery of features that could be used to distinguish between natural and synthetic ametrine from The Journal of Gemmology; from the orientation of growth striations to the interference patterns caused by twinning.

What about natural ametrine?

Ametrine is a bicolored quartz variety that contains both amethyst and citrine zones in the same crystal. The only significant source of natural ametrine is eastern Bolivia’s Anahi mine, where it occurs in veins in a dolomitic limestone. The amethyst-citrine bicoloration results from quartz precipitation at very specific geochemical conditions, temperatures, and growth rates. The combination of amethyst and citrine colours in natural ametrine from the Anahí mine has been attributed to colour zoning that differentiates rhombohedral r (violet) and z (yellow) growth sectors.

The colour of iron-bearing quartz depends on the valence state of the iron. The citrine colour in Bolivian ametrine appears to come from the incorporation of very small aggregates of Fe3+. The amethyst colour develops in two steps. First, individual Fe3+ ions replace Si4+ ions in the quartz structure. To develop the amethyst colour, the crystal must be exposed to ionizing radiation to oxidize the iron in the 4+ state.

Shown in this composite photo are three custom-faceted natural ametrines: a 19.87 ct round StarBrite cut, a 20.35 ct cushion ZigZag cut and a 13.69 ct square StarBrite cut. Courtesy of John Dyer Gems, Edina, Minnesota, USA; photos by Ozzie Campos.

What about FTIR?

FTIR is a technique that measures absorptions within the infrared part of the electromagnetic spectrum. In infrared spectroscopy, IR radiation is passed through a sample. Some of the infrared radiation is absorbed by the sample due to vibrations of molecules in the crystal structure and some of it is transmitted. The resulting spectrum represents a molecular fingerprint of the sample. Infrared spectrometry is very useful to detect impregnations in gemstones (polymers, oils and resin), heat treatment in corundum and to distinguish certain natural and synthetic gem materials. Full width at half maximum is the width of the spectrum curve measured between those points on the y-axis, which are half the maximum amplitude.

What about EDXRF?

X-Ray fluorescence analysis using ED-XRF spectrometers is a commonly used technique for the identification and quantification of elements in a substance.

Beginning in 1994, Russian gem-quality synthetic ametrine entered the market. Synthetic ametrine can be identified by employing advanced techniques, such as EDXRF chemical analysis, and IR spectra. High-resolution (0.5 cm-1) FTIR analysis has shown that a band at 3595 cm-1 is present in the vast majority of natural amethyst. If the 3595 cm-1 band occurs in synthetic amethyst, it has a much larger FWHM (Full width at half maximum) value than in natural specimens. EDXRF chemical analyses revealed higher concentrations of K, Mn, Fe and Zn than in natural ametrine.

What is a conoscope?

The conoscope is a polariscope accessory tool. It is a strongly converging, strain-free glass sphere. When a gemstone is positioned between two crossed polarizers, interference colors that are centered in the specimen will be witnessed with the conoscope when the optic axis is exactly perpendicular to the polarizers.

Previous studies focused on the possibility to separate natural from synthetic ametrine using the refractometer and the polariscope. Quartz is a uniaxial mineral with two unique refractive indexes along its three crystallographic axes. The unique axis is the optic axis. The amethyst-citrine colour boundary in natural ametrine is oriented roughly parallel to the optic axis; in synthetic stones, the boundary is oriented at an oblique angle to the optic axis. The gemmologist needs only to find the direction of the optic axis to determine whether an ametrine is natural or synthetic.

The optic axis in a uniaxial gemstone can be found with a polariscope that has a conoscope lens and, on occasion, with a refractometer. The direction of the optic axis cannot be obtained by refractometer readings for samples cut with their table at random orientation to the optic axis and some difficulties may arise with samples displaying complex colour zoning or twinning.

In this article, the authors explain the possibilities for separating natural from synthetic ametrine by microscopic examination. The immersion microscope was used to look for twinning features, to establish the orientation of the violet/yellow colour boundaries and the direction of growth striations relative to these boundaries, and to observe any characteristic inclusions.

Faceted natural ametrine gemstones from Bolivia typically display only two colour zones, as seen here viewed toward the table facets (top) and toward the pavilions of the same samples (bottom). The stones weigh from 2.45 to 7.45 ct (upper left, 11.7 × 10.8 mm). Photos by K. Schmetzer.

 What are Brewster fringes?

Amethyst from worldwide localities is commonly Brazil-law twinned, which is an intergrowth of right- and left-handed quartz. Such twinning is evidenced only by examination under polarized light. It results in sectors which, when viewed perpendicular to the c-axis, show symmetrical trigonal patterns of dark bands known as Brewster’s fringes. In Bolivian ametrine, these fringes are found only in the alternating amethyst sectors, and not in the citrine sectors.

Between crossed polarizers, the samples show interference patterns (Brewster fringes) that indicate Brazil-law polysynthetic twinning of the violet r growth sectors. Photomicrographs by K. Schmetzer, in immersion.
Optical FeatureNaturalSynthetic
Twinning

Violet growth sectors are intensely twinned on the Brazil law, showing various forms of Brewster fringes with crossed polarizers;
yellow growth sectors are not polysynthetically twinned.

Violet and yellow growth sectors are primarily untwined; small areas within the violet growth
sectors may be twinned on the Dauphiné and/or the Brazil law.

Violet/yellow boundaries Mostly parallel to the c-axis or only slightly inclined to the c-axis (up to about 10°).

Inclined between 20° and 38° to the c-axis.

Growth striations Violet growth sectors: inclined at about 67° or 38° to the violet/ yellow boundary; yellow growth sectors: none observed.

Violet growth sectors: parallel or almost parallel to the violet/ yellow boundary, mostly inclined
at angles between 0° and 8°, with a maximum inclination of 18°; yellow growth sectors: very
weak striations parallel to the basal face.

Fluid inclusions

Rare fluid inclusions, occasionally reflecting the polysynthetic twin pattern of the violet growth zones.

Rare two-phase (liquid and gas) inclusions elongated parallel to the c-axis.

Table showing diagnostic features of natural and synthetic ametrine using immersion microscopy.

The microscopic procedure for identifying these key features can be summarized as follows. The examination of a faceted sample of unknown origin should begin by orienting the dominant colour boundary perpendicular to the rotation axis of the sample holder. If the stone is natural, the typical interference pattern with Brewster fringes will be revealed upon rotation of the sample.

Furthermore, growth striations inclined at relatively large angles to the colour boundary will be observed in the violet portion of the stone after a rotation of about 40° versus the c-axis. If the sample is synthetic, rotating the sample generally will not bring the optic axis into view, and violet growth striations parallel or at a small angle to the violet/yellow colour boundary frequently will be present. It is possible to find the optic axis in a synthetic sample by moving it to other orientations within the sample holder, in which case an untwined interference figure normally will be seen.

In natural ametrine, the colour boundary between the violet r and yellow z growth zones more-or-less follows a prismatic m crystal face but is not exactly planar. In addition, growth striations are present in the violet r sectors, and they are parallel to an external r face and inclined to the violet/yellow boundary. The angle between the growth striations and the colour boundary measures approximately (A) 67° or (B) 38°. Photomicrographs by K. Schmetzer, in immersion.

Separating synthetic ametrine from its natural counterpart using conventional gem lab equipment is possible, provided that the gemmologist has a good understanding of the morphology and optical mineralogy of both natural and synthetic material. The authors insist to use immersion for microscopic observations as the various patterns or structures observed without are of less diagnostic value.

This is a summary of an article that originally appeared in The Journal of Gemmology entitled 'Distinction of Natural and Synthetic Ametrine by Microscopic Examination - A Practical Approach' by Karl Schmetzer 2017/Volume 35/ No. 6 pp. 506-529

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: Crystal clusters that occupy the storage room of the company Minerales y Metales del Oriente in Santa Cruz, Bolivia. Only small portions of the crystals are of facetable quality. Photo taken in 1997; courtesy of Udo Reimann.


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

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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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Gemstone of Passion: Padparadscha sapphire

Considered to be among the most beautiful of the corundum gems with its delicate colour, Padparadscha sapphire has recently hit the headlines thanks to Princess Eugenie of York’s engagement ring. Here, we explore this majestic gemstone fit for royalty.

Om mani padme hum – “Hail the jewel in the heart of the lotus”
- Buddhist Mantra

With recent royal exposure placing this gemstone in the media limelight, the public has been left with a burning question - what exactly is a Padparadscha sapphire?

Whilst considerably unknown to most, Padparadscha sapphires, recognisable for their delicate salmon pink tones, are prized among connoisseurs of the gem world. Just like other sapphires, the Padparadscha has a hardness of 9 on the Mohs scale, making it one of the hardest gemstones in the world (and ideal for engagement rings!). 

Sapphires get their colour from different trace elements. The presence of iron and titanium is responsible for blue tones, while traces of chromium cause pink tones. Ruby red is a result of more chromium present in the stone’s chemical composition. The Padparadscha sapphire is the rarest form of sapphire corundum, balancing on the colour boundary between pink and orange.

Deriving from the Sinhalese word for ‘aquatic lotus blossom’, the Padparadscha has stirred much debate amongst gemmologists, buyers and collectors about what colour spectrum constitutes a Padparadscha over, say, a pink sapphire or orange sapphire. Like all gemstones, Padparadscha sapphires are not easily identified as they have their own individual colour zoning with some displaying lighter mediums of pink and orange or colour zoned with yellow. In terms of value, this type of sapphire increases in value as the saturation of colour increases.

The rarity of these sapphires is due to their limited locale and sourcing. Whilst commonly found in Sri Lanka, Padparadscha sapphires are also found in Tanzania and Madagascar. Padpardaschas sourced from Madagascar are usually pinker than orange but now contribute to a wide percentage of the stones available on the market today, whilst those from Tanzania tend to be browner. Whilst many gemmologists insist that the only ‘real’ Padpardschas come from Sri Lanka, new sapphires from Madagascar continue to be a beautiful and unique addition to the market supply. 

Read more: An examination of the problem of separating pink sapphire and padparadscha from ruby

Today, many Padparadscha sapphires from Madagascar are heat-treated to enhance their pinkish colour at much lower temperatures to those sourced from Sri Lanka. A widespread treatment for corundum that induces the orangish-pink colour is Beryllium diffusion. The market is awash with these treated stones, therefore a lab report is essential when purchasing a naturally coloured Padparadscha sapphire.

Of course, Padparadscha sapphires have caught the attention of the media since Princess Eugenie of York, the granddaughter of Her Majesty the Queen and daughter of Prince Andrew, Duke of York, and Sarah Ferguson, Duchess of York, got engaged to wine merchant, Jack Brooksbank, in January 2018.

Her ring, which is not dissimilar to the ring Prince Andrew presented to Sarah Ferguson in 1986, features an oval-cut Padparadscha sapphire surrounded by a halo of diamonds. This is set on a yellow gold band with two further tapered diamonds at the shoulders.

Will Padparadscha sapphires be the surprise hit of 2018? Perhaps the Tucson and JCK trade events in January and June, respectively, will reveal a surge of popularity for this particularly lovely sapphire.

Gem-A would like to thank Richard Hughes of Lotus Gemology for his support in compiling this article. 

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: Princess Eugenie and Jack Broosbank via The Royal Family, Instagram. A 4.5ct unheated Padparadscha sapphire ring courtesy of the Somewhere In The Rainbow Collection


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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Birthstone Guide: Emerald for Those Born in May

Those born in May are lucky enough to count emerald as their birthstone. Here, Gem-A gemmology tutor, Lily Faber FGA DGA EG, explores the history and qualities of this beautiful green beryl. 

The emerald is arguably the most well-known and desired member of the beryl family with its brilliantly verdant colour. Green stones have been called emeralds for thousands of years -  since around 4,000 BC - regardless of whether they actually were what we know as emeralds today.

Emerald Meaning and Myths

At one time, emeralds were believed to give one the ability to predict the future, especially when held underneath the tongue. They were also believed to confer riches upon the wearer and were used as protection against poison and demonic possession. Used as a symbol of immortality and wealth, emeralds have been valued for centuries for both their appearance and symbolism.

 Beryl Emerald Crystal in Calcite Matrix and Carbonaceous 9767 GemA PDEmerald crystals in calcite. Photographed by Henry Mesa.

Finally, it is said that emeralds are beneficial for the eye and it is reported that some lapidaries keep an emerald on their bench to look at, giving relief to their  tired eyes after a long day of cutting gems.

Emerald Gemstone Localities

Emeralds have been mined for thousands of years, stretching back to Egypt near the Red Sea around 2000 BC in what were known as Cleopatra’s emerald mines. While Egyptian emeralds were some of the first to be mined and traded, it was the discoveries of Colombian emeralds by 16th century Spanish conquistadors like Pizarro that brought strikingly saturated green crystals to the European market - particularly to the Spanish court and beyond.

Emerald Crystal Emerald and Emerald Cut Connection Gem A BlogA large Colombian emerald crystal. Photograph by Henry Mesa. 

It is still thought that emeralds from the Colombian mines such as Chivor, Muzo and Cozquez are the finest in the world. Other localities that produce emeralds are Brazil, Russia, India, Zambia, Zimbabwe, Madagascar and North Carolina, USA. 

Emerald Crystals

Emeralds typically form as hexagonal prisms with a flat pinacoid top and base. Sometimes, they can have rectangular etch pits on the prism faces and hexagonal etch pits on the top of the crystal.

Pyrite Inclusion in Emerald.

Due to their brittle nature, these gemstones often have internal fractures along with many different types of inclusions. Emeralds are routinely oiled or even resin-filled, to reduce the appearance of these internal fractures. It is possible to see a blue or yellow flash within the stone if it has been filled with a resin, but careful observation is needed. 

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

Also found in Colombia are trapiche emeralds, in which an emerald forms with a central, hexagonal crystal from which radiate six emerald segments that are separated by a fine-grained mixture of colourless beryl and nearly black albite. 

Emerald Gemstones Inclusions 

Inclusions are numerous and varied, and sometimes one can tell where the emerald was mined based on what lies inside the gemstone. Colombian emeralds, for example, typically have three-phase inclusions, which consist of a liquid, a solid mineral inclusion and a gas bubble contained in a jagged cavity.

Read more: What Makes a Gemstone Rare? 

Other inclusions typical of their localities are comma-shaped two-phase inclusions found in Indian emeralds, and long, curved tremolite inclusions in emeralds from Zimbabwe. There are many other inclusions such as bamboo-like actinolite, pyrite and colourless rhomb-shaped crystals.

 
Three Phase Inclusion in Emerald.

Emerald Cut 

There is a type of square or rectangular step-cut with truncated corners that is so often used for this gemstone that it is more commonly known as the emerald cut. The corners are removed so as to protect the brittle stone from unwanted chipping and breakage at the stone’s most vulnerable points.

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

Claw settings are used, particularly at the corners and along the sides, but a more practical setting would be the bezel or rub-over setting in order to form a barrier around the entire stone. Whether you love emeralds or prefer another type of beryl, there is no arguing that its deep green colour and lore make it a gemstone to be admired. 

Start your gemmology journey with a Gem-A Workshop, designed to get you up-to-speed with the basics of gemstones. Find out more here

The Gem-A Gemmology Foundation course is the ideal way to turn your passion for gemstones into something more. Discover all our gemmology courses here

Cover image: Emerald in quartz by Henry Mesa.

Additional Info

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Focus on Gemstone Fluorescence: Looking for the Light

Most of us know about fluorescence in gemstones, but how many use it as part of their gemmological testing routine? Here, Gem-A gemmology tutor Lily Faber, FGA DGA EG, delves deeper into fluorescence and explains why it can be both enlightening and enjoyable for gemmologists.

Luminescence in Gemmology

When we use the term luminescence in gemmology, it generally refers to the term photoluminescence, which is the emission of a cold, visible light when a gem material (or general substance) is excited by light of a shorter wavelength. Two examples are fluorescence and phosphorescence.

Fluorescence occurs when a gem material is illuminated by radiation of shorter wavelengths with higher energy.

A bag of cubic zirconia under LWUV with areas of blue fluorescence that highlights the presence of diamonds. 

The visible light emitted stops when the source of illumination is turned off. Phosphorescence, on the other hand, is a visible light that is emitted by a gem material after the original source of exciting radiation has been switched off.

The Hope Diamond Phosphorescence

A famous example of a gemstone that strongly phosphoresces is the blue Hope Diamond, which glows a bright red for several minutes after being excited by short wave UV light. Both fluorescence and phosphorescence can have varying strengths from very strong to weak. If a material does not either fluoresce or phosphoresce, it is considered inert.

Quartz under LWUV showing oil inclusions.

The History of Gemstone Fluorescence

Fluorescence has been observed for years, but it was not until Sir George Stokes extensively documented this effect in relation to gemmology that it officially became part of the scientific lexicon. In 1852, Sir George coined the word fluorescence, named after fluorspar, more commonly known as fluorite, which is a highly fluorescent material.

The ‘Stokes Law of Fluorescence’ or ‘Stokes Shift’ states that the fluorescent emission of light will always be that of a longer wavelength than the excitation source, i.e. the light emitted is of a lower energy than its excitation source.

Why Use Fluorescence to Test Gemstones?

Fluorescence can be a helpful tool when used correctly. Some gemstones have a characteristic or, very rarely, a diagnostic reaction to UV light. One gemstone that notably both fluoresces and phosphoresces is a diamond, which typically fluoresces blue in longwave UV light and then phosphoresces yellow.

This is a diagnostic result for a colourless to yellow diamond in the Cape series (Type Ia), but please be aware that fluorescence is rarely diagnostic as reactions may vary wildly within the same species or variety of gemstone.

READ MORE: The Fascinating History of Platinum

Fluorescence can indicate or confirm the identity of a stone. For example, citrine quartz is inert to fluorescence due to the presence of iron, which eliminates fluorescence. If you are testing a yellow stone that may potentially be a citrine, and it fluoresces orangey-yellow under LWUV and red under SWUV, it cannot be a citrine and is more likely to be a scapolite.


Scapolite from Ontario under LWUV.

Other reasons to use fluorescence? It is quick and normally takes less than one minute to observe reactions. You can test gemstones that are loose, set, rough or fashioned, and you can test either single gemstones or multiple gems at the same time. Finally, it is entertaining!

How Does Fluorescence Occur in Gemstones?

Ultraviolet light (UV) is the most commonly used excitation source. We cannot see UV light as it sits just below the visible light spectrum (400nm- 700nm) at 10-400nm. UV light enables us to see fluorescence because a gem material will absorb this radiation source and then emit light that is lower in energy and therefore visible to the eye. But what is actually happening within the gemstone itself to elicit such a colourful reaction?

It has to do with electrons. When electrons are excited by a source of radiation, they jump to a higher energy level around the nucleus of the atom. The excited electron remains in this excited state for a short period of time until it falls back to its original ground state. As the electron returns to its ground state, it emits energy either as heat or as visible light (fluorescence).


A: Natural spinel, red paste, synthetic verneuil ruby, almandine garnet and two natural rubies.
B: The same stones under LWUV. C: The results under SWUV.
 

If you are wondering if all minerals fluoresce, the answer is no. Only 15% of all known mineral species exhibit this effect, the causes of which can be very complex. One of the more better-known and documented causes is the presence of activator elements that can be excited by higher energy wavelengths.

Some activators include chromium (Cr), uranium (U), manganese (Mn), lead (Pb), titanium (Ti) and rare earth elements (REE). Some elements are considered to be the complete opposite, however, and when present they eliminate or quench fluorescence, causing a gemstone to be inert. Common quenchers include iron (Fe) and nickel (Ni).

 
Kunzite under SWUV.

Using UV Light to Test Gemstones

The types of UV light used in testing are long wave (LWUV) with a principle wavelength of 365nm, and short wave (SWUV) with a principle wavelength of 254nm. Different testing equipment ranges from UV keyrings (typically LWUV) to a UV viewing cabinet. When using UV light to test gemstones, it is important to remember that any exposure to UV light can damage your eyes, but particularly use caution when using SWUV as it is more dangerous than LWUV. Always wear protective UV goggles or ensure that your UV cabinet is installed with an eyepiece that filters out UV light.

To properly use a UV keyring, take the following steps:

  • Never look directly into the light
  • Turn off surrounding lights so you are in a dark environment.
  • Place the gemstone table-down if facetted. If table up, the gemstone may reflect the UV light into your eyes and creating confusing, conflicting or inconclusive results.
  • Hold the keyring approximately two inches away from the stone and, if testing multiple gems, always be consistent with the distance at which you hold the light.
  • Record whether the stone is inert or fluorescing, and the strength of the reaction.

Sometimes you may see some dull purple or red light in the gemstone or on a few facet edges. This means that the gemstone is reflecting the purple UV light and is not itself a fluorescent reaction.   


A: Synthetic verneuil sapphire, scapolite, natural sapphire, topaz and citrine. B: Under LWUV. C: Under SWUV 

Understanding Fluorescence Results

While fluorescence is not a diagnostic test, and results can vary dramatically even within the same gemstone species (variable emerald results, for example), it can be a useful indication of what a gemstone is. When testing diamonds and colourless, transparent simulants, keep the below chart in mind.

When testing red to pink gemstones,do keep in mind that natural rubies in particular may have variable fluorescence based on their iron content. If iron is present, the ruby will have minimal to no fluorescence. Synthetic rubies tend to have much stronger fluorescent reactions.

When testing green gemstones, fluorescence can be tricky to use for identification purposes. However, it may be useful in terms of recognising the presence of fillers in emeralds or green jadeite jade, for example.

Some resin fillers fluoresce a whitish colour under LWUV and if this reaction is seen in either of the aforementioned stones, it may be an indication that filler is present, especially if the fluorescence is concentrated in seams or certain areas rather than being evenly distributed across the stone.

Note the natural emerald fluorescing a whitish colour (second from right), hinting that a resin filler may have been used. Further testing will be needed to confirm this possibility.

Left to Right: synthetic flux emerald, synthetic hydrothermal emerald, natural emerald, chrome diopside.

Additionally, natural emeralds, if they do fluoresce, will have a red to inert reaction under LWUV, and a weaker inert or green reaction under SWUV. Synthetic emeralds may fluoresce red or, in the case of the synthetic hydrothermal emerald, they may be inert if doped with iron to imitate a natural inert reaction.

Untreated green jadeite does not fluoresce, so any other reaction should be regarded with suspicion and further testing will be needed. When testing yellow gemstones the bottom chart may prove useful.

Conclusion - Fluorescence in Gemstones

As is evident, fluorescence can be a helpful tool when testing gemstones, though not always diagnostic. It is a quick test that is one of the more exciting ones in the world of gemmology. ■

All images courtesy of Lily Faber and Gem-A gemmology tutor, Pat Daly.

Colourless Gemstones

LWUV

SWUV

Diamond (natural)

Strongest reaction, most common is blue, but can be yellow and green

Similar colours to LWUV but it is a weaker reaction

Diamond (synthetic)

Similar colours to SWUV but it is a weaker reaction

Strongest reaction, mainly fluoresce orange to yellow

Cubic zirconia

Yellow to dull-orange, variable

Weaker reaction to LWUV or inert, similar colours

Synthetic moissanite

Variable reactions

Variable reactions

Synthetic spinel

Inert

Bright, chalky white or blue/green

Paste

Inert

Variable, may have chalky white surface

 

Red and Pink Gemstones

LWUV

SWUV

Ruby (natural)

Variable, strong red to inert

Same as LWUV but weaker to inert reaction

Ruby (synthetic)

Bright red, tends to be stronger than natural ruby

Red, weaker than LWUV but still brighter than natural ruby

Red spinel

Red

Red, but weaker than LWUV

Spodumene, var. Kunzite

Orange or violet

Weaker violet, whitish or inert

Almandine garnet (Iron is present, this stone never fluoresces)

Inert

Inert

Red glass/paste

Inert

Variable, may have chalky white surface

 

Yellow Gemstones

LWUV

SWUV

Quartz, variety cirtrine

Inert

Inert

Yellow sapphire (natural)

Apricot orange to inert

Inert

Yellow sapphite (synthetic)

Weak red to inert

Inert

Yellow scapolite

Yellowish

Reddish

Yellow topaz

Yellowish

Whitish

This article originally appeared in Gems&Jewellery Summer 2018/ Volume 27/ No.2 

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: Willemite and calcite fluorescing under SWUV.


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...

Investigating Fake Rough with Gem Testing Laboratory Jaipur

From the Summer 2018 issue of Gems&Jewellery, Gagan Choudhary FGA, deputy director of Gem Testing Laboratory Jaipur, describes the various types of fake gem rough that has passed his desk in recent months, including mica rock presented as emerald rough, cubic zircona and topaz fashioned as diamond octahedtrons, and synthetic quartz mimicking aquamarine.

Reaching directly to the miners for procuring rough has always been profitable, but involves a huge amount of risk unless one has enough experience in buying at the source, deep knowledge about the stone being purchased, and handling the pressure thereof.

Often, there have been cases when dealers tend to forget the possibilities of scams and frauds at mining sites or the markets nearby. The sellers at such locations often present glass, synthetics, treated gems or other cheap natural materials as expensive gems in order to make some quick money. This practice has been prevalent at most of the major mining regions around the world for decades.

At Gem Testing Laboratory Jaipur, we routinely encounter such cases, some of which are presented here:

GLASS-FILLED MICA-ROCK, PRESENTED AS EMERALD ROUGH

Recently, a 1,075 gm black micaceous rock was presented for identification (1), a true example of a fraudulent rough, which, although not shocking to us, was definitely an interesting one. Initial observations with unaided eyes from different angles suggested the presence of several crystals, with hexagonal profile, embedded in the rock.

Such rock formation is a common sight for those dealing in emerald rough, especially from locations where emerald is associated with mica (phlogopite) schist, such as Zambia. Careful observation using strong fibre-optic light surprised us. Under reflected light, only small areas or corners of the embedded crystals appeared green.

The rest appeared dark, due to the presence of black mica on and around crystals.

1: This 1075 gm micaceous rock was embedded with elongated ‘hexagonal’ crystals of artificial glass (marked with arrows).
Note the difference of texture around embedded crystals and rest of the rock.

However, when light was transmitted through these crystals, they appeared bright green, which raised suspicion about their origin. Such bright green colour under transmitted light, especially in an embedded crystal, had never been seen before. Further examination revealed a granular texture around these embedded crystals, while the rest of the rock appeared flaky; this supported our suspicion.

These features suggested that micaceous rock was first drilled, filled with green ‘hexagonal’ crystals artificially, and then the joints were covered with a mixture of glue and black mica.

When observed under ultraviolet light,  corners of the embedded crystals (micafree areas) fluoresced chalky-yellow green. Raman analysis confirmed these embedded crystals as artificial glass. 

MICA-COATED GLASS IMITATING EMERALD ROUGH

Another form of emerald-rough imitation are these mica-coated glass (2). In this case, pieces of green glass are first fashioned in the shape of hexagonal rough, which is then coated with fine powder of black mica mixed in glue, followed by a layer of mica chips. These worked-up pieces are then taken to the mining sites by the middlemen and mixed in parcels of low-quality natural emeralds.

The illustrated glass specimens here were seen in a parcel of emeralds from Jharkhand, India.

 2. Glass samples worked-up to imitate emerald rough by fashioning into hexagonal crystals and coating with black mica.
Found mixed in a  parcel of natural emerald. 

SYNTHETIC RUBY FROM MOZAMBIQUE

We came across a small parcel of rough rubies (five pieces, weight range of 3.60- 18.06 ct) submitted for identification. All the specimens were tumbled with a corroded surface and interestingly coated with a yellow-brown substance. Most of the samples were free from inclusions, but under immersion microscopy all displayed curved growth lines, characteristic of synthetic ruby grown by Verneuil process (3).

Appearance of these specimens clearly suggested that they were presented as natural. Prior to this we have seen many more specimens of synthetic ruby, and in much larger sizes, presented as natural. As per the discussion and information from the depositor, these stones were purchased in Mozambique.

3. Rough Samples weighing 3.60-18.06 ct were identified as synthetic ruby. 
note the presence of yellow-brown substance on the extreme right, imitating mud on natural rough

NATURAL AND SYNTHETIC RUBY COMPOSITE

This 28.73 ct bright red rough, associated with some black and white minerals, was presented as a natural ruby. Upon initial examination with unaided eyes, the surface displayed some areas of milky angular zones against a pinkish to purplish background, typically seen in natural ruby crystals.

When examined under transmitted light, a large central area of the specimen appeared bright red, while the edges appeared dark and opaque (4). This raised suspicion about the origin of this rough.

Careful examination under the microscope revealed a sudden change. of growth and inclusion patterns, not only in the core and surface, but also within the surface; the surface displayed small chips with different inclusion patterns.

In addition, distinct colour variation between the core and edges of the specimen was evident. These features suggested that the specimen is a composite where a transparent piece of synthetic ruby is covered with small chips of natural ruby.


4.This bright purplish red-pink rough(top) is a composite of synthetic and natural ruby. The central part is a synthetic ruby while the out part is composed of chips of natural ruby.
Under transmitted light (bottom) the central synthetic part of the specimen appeared bright red, while the edges appeared dark and opaque.

SYNTHETIC SAPPHIRE, PRESENTED AS NATURAL ROUGH

Synthetic counterpart is a common imitation for natural sapphire rough; these are presented in two forms — one as broken, tumbled rough, and second, as fashioned, well-formed hexagonal-pyramidal crystals with surface markings (cover image). Although, their identification is not challenging in a gem lab, they might pose problems while buying at the mines.

The specimen illustrated in (5) was found mixed in a parcel of sapphires, purchased in Madagascar.

5. These two crystals, weighing 63.93 (left) and 44.66 (right) ct displaying bipyramidal habits and associated white mineral, were submitted as sapphire.
The crystal on left was identified as sapphire, but one on the right as glass.

GLASS AS SAPPHIRE ROUGH

Two blue crystals weighing 63.93 and 44.66 ct, as illustrated in were submitted together. Both crystals displayed bi-pyramidal habits and associated white mineral, typically seen in corundum. Interestingly, there was an obvious difference in colour and transparency of both the crystals; the crystal on the right had much better colour and transparency.

Closer inspection of the bright blue crystal revealed hemispherical cavities on its surface, coloured swirls and numerous gas bubbles — the features associated with glass. The grey-blue crystal (5, left) was proved to be natural sapphire, while crystal habit and associated white mineral (kaolinite) suggested Kashmir as its origin.

CUBIC ZIRCONIA AND TOPAZ AS DIAMOND OCTAHEDRON

Cubic zirconia as diamond imitation, both rough as well as cut, have been in existence for a long time, however, in recent years colourless topaz has become a frequent encounter in diamond imitation, especially in rough form. Image 6 illustrates one such example, where the left specimen is a cubic zirconia while the right one is topaz.

6. Cubic Zirconia (left) topaz (right).

These stones are fashioned as typical crystal forms associated with diamond, here, octahedron; often striations, grooves or triangular markings are created on these fashioned octahedrons, giving them a natural appearing crystal.

In the recent past, this author has encountered some large packets of such created ‘topaz octahedrons’, being presented as diamond.

Separation of cubic zirconia from diamond was easily done on the basis of higher specific gravity, while topaz by its anisotropic optic character. Although identification of these imitations is straightforward, when buying at mines or open markets one has to be careful. 

TREATED QUARTZ AS EMERALD ROUGH

In addition to the glass discussed above, emerald rough is often imitated by coated (7) or dyed quartz.

There have been cases where transparent quartz is painted with green colour and presented as emerald, however, as illustrated in 7 (left), such materials can be separated by crystal form (prism and rhombohedral faces) and horizontal direction of grooves or striations on prism faces.

Another material is the quartzite variety, which is first dyed green, then fashioned as hexagonal crystal shape to imitate emerald; such fashioned crystals are often coated with black mica too.

Even body colour, translucency and absorption spectrum (band at 650 nm) can separate such dyed materials from natural emerald.

 
7. Quartz crystals painted with green colour and coated with black mica are presented as emerald rough.
Also note the horizontal direction of grooves or striations on prism face.

SYNTHETIC QUARTZ AS AQUAMARINE CRYSTAL

This is one of the most unusual materials this author has seen for making a fake crystal — synthetic blue quartz fashioned as an hexagonal crystal of aquamarine (8). The crystal was fashioned into six-sided prisms, with pyramids and basal pinacoids — a crystal form commonly seen in aquamarine.

The crystal also contained a conical-tube with brown epigenetic material (such as iron oxide filling) visible to the unaided eyes. On observing the crystal from different sides, it displayed two parallel planes (seed plate) with colourless area and an attached metal clamp. Such features are often seen in synthetic quartz and other gems grown by hydrothermal process.

When viewed from the top i.e. down the ‘c’ axis, the interfacial angles between the prism faces ruled out the possibility of natural crystal form associated with crystals belonging to hexagonal crystal system, such as beryl.

As per the precision at which the nature operates, opposite sides of prism faces are parallel to each other, while in this case no opposite sides were parallel. Identification of this specimen as synthetic quartz was established on the basis of ‘bull’s eye’ optic figure, seed plate and infra-red spectra.

Such cases remind us of the importance of studying crystallography, not only for the identification of gem rough, but also in the creation of fake rough, which the maker of this fake missed out on.


8. Left: blue specimen presented as aquamarine was a synthetic quartz fashioned into a hexagonal crystal, terminated by pyramidal and pinacoidal faces. Also note the conical tube containing brown epigenetic substance. 
Right: the top view of the synthetic quartz specimen

CONCLUSIONS

Fake rough is an inevitable part of the gem trade, and the scams associated with this are increasing day-by-day. Identification of rough, especially in the field is quite challenging, however, one needs to keep in mind the existence of fake material in local markets or even mines.

Careful inspection of the presented rough before making a buying decision is always advisable, keeping in mind the crystallographic features. ■

All images courtesy of the author.

This article originally appeared in Gems&Jewellery Summer 2018/ Volume 27/ No.2 

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: Synthetics presented as natural rough tumbled sapphire. Image Credit: Gagan Choudhary. 


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Interview: Steve Moriarty of Moriarty's Gem Arts on a Lifetime in Gemstones

From the Summer 2018 issue of Gems&Jewellery, Gem-A Associate Member and co-owner of Moriarty's Gem Arts, Steve Moriarty, shares his fascinating career in gemmology.

Although a gem specialist’s career can often start confined to a classroom or a lab, pouring over stone samples and peering through a microscope, our industry also offers wonderful opportunities to travel around the globe.

Steve Moriarty is not only the co-owner of Moriarty’s Gem Art in Crown Point, Indiana, but also an experienced gem-cutter and gem explorer. His family-run business, including the websitesmoregems.com, tanzanitejewelrydesigns.com, opallust.com and mothersfamilyrings.com, was founded in 1975, and today Steve, his wife Nancy, and two of their three children work together to offer a gem-orientated retail experience. Add to this Steve’s 25-years as a professional gem-cutter and it is clear that he has seen, worked with and sold some incredible gemstones.

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“Ever since I was young, I collected rocks and fossils,” Moriarty comments. “I really got interested in the gem business while I was in college; my brother Tom started importing gems from India and would send me stones, which I took to the jewellery arts classes to sell.”

Despite a stint as a chemist, Moriarty opted to follow his passion for gems and in 1975 he joined his brother selling coloured gems to jewellers in the Midwest United States. In these early years, Moriarty says that “colour was not important to most jewellers,” which made businesses like his rare in the region. “My wife Nancy and I started on our own as Moriarty Gem Corporation in 1984 and I began travelling overseas to Thailand for cut gems.” By 1994, with his passion for travelling, buying gems and selling them to retailers waning, Moriarty established his own retail store – now Moriarty’s Gem Art – in Crown Point, Indiana.

A rough garnet and its cut and polished counterpart. Image Courtesy of Steve Moriarty and Moriarty's Gem Arts.

He says: “Cutting gems, creating jewellery, custom orders and four websites is almost more than we can handle at times! I love to cut gems, this is my first priority. But to sell enough of those gems you need to do something with them, and many of the gems end up [as] unique shapes, so most everything is a custom piece. The greatest difficulty my designers and I have is we want to be artists and create our vision, but most often we have to recreate the customer’s vision, or what they saw on Pinterest or somewhere else online.”

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Despite this, the frustrated gem artist in Moriarty is usually restored by incredible finds and far-flung travels. When asked to describe his most inspiring trips, Moriarty points to the early 1980s, when a trip to Kenya revealed that the border to Tanzania had just been opened to American tourists. “The next day we were off on the five hour bus ride from Nairobi to Arusha, and my love of tanzanite began,” he says.

On a later trip in the early 2000s, Moriarty and his long-time travelling colleague, Jim Fiebig, discovered an “amazing cornucopia of gems” in Madagascar. He says: “There was so much amazing material that we were rejecting great gems just because they were priced a little high compared to the abundant bargains we were getting. I had many great trips to Madagascar after that, buying many of the finest quality gems I have ever owned, but never again in such quantity as the first trip.”

Today, Moriarty focuses his freeform carving attentions on Ethiopian opal, which can “require up to two full days to get a decent polish” because of the undulating surfaces.

READ MORE: Investigating Fake Rough

In addition, Rwandan amethyst, carved by Moriarty, recently appeared on the cover of Gem-A’s The Journal of Gemmology (Vol.36 No.1). Although amethyst is not high on Moriarty’s carving ‘wish list’, this material was particularly impressive. “I had been cutting Uruguay material for 20 years and considered it to be amongst the finest in the world, but when I saw the intensity of the secondary red and blues [in the Rwandan amethyst], I was hooked.”

Moriarty also mentions daylight fluorescent hyalite opal from Zacatecas, Mexico — another find that truly inspired him. After discovering some specimens at the Denver Gem & Mineral Show, he returned home and ended up cutting 7.27 carats — one of the largest faceted opals of this type. “We posted our video on YouTube just before we went to Tucson and someone shared it on reddit.com. In three days, it had been viewed over a million times. Currently, total viewing is over three million.”


Left: Hyalite opal from Zacatecas, Mexico, fluorescing in the daylight. Right: the same opal under UV light.

He continues: “I spent some time looking for hyalite opal to compare pricing, but was unsuccessful finding any cut stones in Tucson 2018. One dealer who specialises in rare gems, did give me an idea of the price [as he had] sold one of five carats. This led me to immediately call my office and have them put the hyalite in the safe and take it offline. It seems this material, discovered in 2013, was mined out by 2016 and was very unique for its characteristic of daylight fluorescence. Our next call was to the dealer who sold me the rough and we met and purchased anything of quality that he had left.”

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There is an excitement to this lifestyle, of chasing down gems, that is particularly appealing to those getting started in the field. However, Moriarty also enjoys cutting his ‘old favourites’. He explains: “I love cutting garnets and although the prices for garnets of unusual colours have gone up dramatically, I still think they are under-valued. When I get done with a garnet, to me, it looks as good as any diamond I have ever seen.”

Despite his love of travelling, Moriarty is enjoying the fact that his latest obsession – Oregon sunstone – is much closer to home. And who can blame him for wanting a little more time? After all, there are gems to cut, custom orders to fulfil and a wealth of websites to be cared for… it is all in a day’s work for the Moriarty family. ■

All images courtesy of the author.

This article originally appeared in Gems&Jewellery Summer 2018/ Volume 27/ No.2 

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: Cover of Gems&Jewellery Summer 2018. Image Credit: Gem-A. 


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Retail Focus: Exploring the Emeralds of Colombia

From the Summer 2018 issue of Gems&Jewellery, Gem-A gemmology tutor Beth West FGA DGA EG explores the Musica people and the emeralds of Colombia. 

There is a brooch displayed at the heart of the Geology, Gems and Minerals Gallery in the Smithsonian Institution in Washington, USA.

It is centred on a large luminous green emerald surrounded by diamonds as sharp as stars. It is undoubtedly beautiful; designed by Tiffany & Co. in the 1950s, it evokes an era of glamour and grace. But as exceptional a piece of design as it may be, the brooch is little more than a throne for the emerald that it carries.

The Hooker Emerald, named after the Institution’s principal benefactor, Janet Annenberg Hooker, weighs 75.47 carats and was originally extracted from present-day Colombia in the 16th century, when talk of the majesty of these gems had only just begun to travel.

Emerald, Composite Soude, Image Credit: Gem-A

READ MORE: Steve Moriarty on a Lifetime in Gems

The Spanish Conquistadors arrived in the ‘New World’ in the last decade of the 15th century.

When Hernan Cortez was presented with emeralds by the Aztec Emperor Montezuma II in 1519, the allure of the green gem incited the greed of the invaders and a bid to uncover their source was advanced, often leading to violence and the ultimate mistreatment of the indigenous tribes.

While emeralds became symbols of status and wealth at the end of the trade route set up by the Spanish to India and Europe, what did these stones mean to the original inhabitants of the luscious and majestic Andean terrain?

The first of the tribes’ emerald deposits was located by Conquistador, Gonzalo Jimenez de Queseda in 1537 in the village of Somondoco – home to the Muisca (or Chibcha) people.

This deposit would come to be known as ‘Chivor’, meaning ‘our farm fields, our mother’ or ‘green and rich land’ in the native tongue of the Chibcha, a reference to the emeralds un-earthed there.

Lush Colombian Landscape. Image Credit: Pixabay.com

The Muisca people were one of the four principal civilisations of the Americas.

The other three, the Incas, the Mayans and the Aztecs are perhaps more prevalent in Western thought due to the grandeur and ceremony of the architecture that remains as evidence of their complex culture.

But the Muiscas were no less advanced; they were a self-sufficient people existing in comparative isolation in the highlands of the Cordillera Oriental of the Northern Andes.

It is in this Eastern chain of peaks that pockets of the finest emeralds had formed.

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The abundance of the precious mineral within the Muisca’s territory, and the ability of the people to mine it efficiently, made it an important economic resource.

Markets were held regularly in conjunction with calendared festivals during which the Muisca would trade the emeralds with gold from the Guane people from north of the Chicamocha River, yopo (a hallucigenic snuff), exotic feathers and jaguar skins from the lowlands, marine snail shells, avocados and the still celebrated ‘ice-cream bean’ from their coastal cousins, the Tairona people.

Emerald in Matrix. Photo Credit: Henry Mesa. 

There is no evidence to suggest that emeralds were ranked higher in value than the other traded goods, but it is apparent that the stone held substantial symbolic weight.

In 1637, the writer Juan Rodriguez Freyle documented an initiation ceremony performed by the Muisca. On the event of a ruler’s death, the successor would be covered with a fine dusting of gold and placed on a raft at the centre of Lake Guatavita.

As music and dancing defined the shores, the new leader would throw gold and emerald votives into the lake as offerings to the Sun God.

This became known as the myth of El Dorado and rumours of a place saturated with such potential material wealth have been, from the time of its discovery to the present day, exploited by the greed of Western adventurers.

This imposition of material desire on the lands of the natives has ultimately led to wars and bloodshed over the centuries.


Emerald in Matrix. Photo Credit: Henry Mesa.

Therefore, is it perhaps worth considering the stance of the Muisca, who did not covet the emerald as their own but accepted it as a spectacular gift from the mountains, and one that they would happily relinquish to maintain harmony with the gods.

If we were to eliminate the profitability of the gem, could we too be able to see deeper into that mesmerising green? Idealistic? Perhaps. I cannot see anyone throwing the Hooker emerald into a lake any time soon. ■

This article originally appeared in Gems&Jewellery Summer 2018/ Volume 27/ No.2 

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: Emerald with Quartz. Image Credit: Henry Mesa.  


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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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Buying Guide: Coloured Diamonds from Least to Most Valuable

The typical image of a diamond tends to be of a clear and colourless stone, therefore it is hardly surprising that these are presumed to have the highest monetary value. In reality, diamonds can present as a range of different colours and uniquely-coloured diamonds can command premium prices.

Coloured diamonds are created when impurities or deformities occur in a diamond’s lattice of carbon atoms, with particular impurities resulting in different colour formations.

The most valuable stones will be those which are purest in colour, most saturated and most even in tone. In order to assess the grades of colour, coloured diamonds are placed into one of nine categories: faint (least valuable), very light, light, fancy light, fancy, fancy dark, fancy intense, fancy deep and fancy vivid (the rarest and most expensive).

The Aurora Pyramid of Hope collection polished diamondsThe Aurora Pyramid of Hope Collection contains the full spectrum of natural diamond colours.
Image copyright Trustees of NHM, London.

Increasing rarity leads to higher retail prices and by examining the variations between some notable types of coloured diamonds, we can see a clear scale of value emerging based on an agreed-upon grading system.

Brown Diamonds

The colouration of brown diamonds is caused by a deformation of the diamond lattice during the gemstone’s growth within or expulsion from the mantle. In fact, 98% of all mined diamonds will have a brown tone, which is generally considered unfavourable. However, thanks to the savvy marketing team at Australia’s Argyle mine, a new trend for ‘cognac’ or ‘champagne’ diamonds emerged in the 1990s.

Yellow Diamonds

Yellow diamonds gain their colour through nitrogen (N) impurities in the diamond lattice. N often finds itself incorporated in the diamond’s atomic structure, as it is similar in size to the carbon atom. If the diamond has been resident in the mantle for a considerable amount of time, the N will aggregate to form a group of three N atoms and a vacancy. This creates a ‘colour centre’ that absorbs light and makes a diamond appear yellow.

Read more: What Makes a Gemstone Rare?

However, the rarest yellow diamonds are the youngest diamonds; in such stones, the N atoms have not joined forces and remain isolated within the diamond’s atomic structure, resulting in the creation of the celebrated ‘canary yellow’. In May 2014 the Graff Vivid Yellow, at a stellar 100.09 carats, brought $16.3 million at Sotheby's.

Pink Diamonds

Similar to brown diamonds, the pink colouration of a diamond is associated with a deformation of the diamond lattice. This would have occurred while it grew deep within the earth’s mantle in areas where tectonic plates collided and mountains formed.

A 1.27 carat fancy intense pink diamondA 1.27 carat fancy intense pink diamond surrounded by eight Argyle fancy intense pink marquise-cut diamonds and 3.36 carats of pear-shape diamonds. Image courtesy of BD Luxury: bdluxury.com

Read more: Discover the Pink Diamonds of the 2018 Argyle Diamond Tender

The Argyle mine in Australia is one of the principal sources for pinks – but they are rare, accounting for only 0.1% of overall production. Testament to its huge popularity, the 18.96ct Winston Pink Legacy diamond fetched a sum of $50,375,000 at Christies in 2018.

Blue Diamonds

The rarest and most sought-after blue diamonds owe their colour to infinitesimal levels of boron impurities and, like canary yellow, account for less than 1% of all natural stones.

Read more: The 6.16 carat Farnese Blue Diamond

Selling for $57,500,000 at Christies in May 2016, the 14.6ct Oppenheimer Blue is the most expensive fancy vivid blue diamond sold to date, and clearly demonstrates that quality blue diamonds can attract premium prices at auction.

Blue diamondAn exceptional 29.6 carat blue diamond recovered at the Cullinan mine, January 2014. Courtesy of Petra Diamonds.

Green Diamonds

The green colouration in diamonds is generally caused by irradiation and the colour is often only skin deep, having occurred in the crust after the gemstone has formed. A natural green diamond of good colour is very rare and highly valuable; the most expensive green diamond ever sold was the 5.03ct Aurora Green for HK $16.8 million at Christie’s in May 2016. However, because it is very difficult to differentiate between natural and artificially irradiated stones, they are treated with caution by the market.

Dresdner Grüner Diamant Neues Grünes Gewölbe DresdenThe Dresden Green Diamond - a 41 carats (8.2 g) natural green diamond, which probably originated in the Kollur mine in the state of Andhra Pradesh in India. Here it is pictured as part of a hat clasp ornament. (By ubahnverleih - Own work, CC0)

Red Diamonds

Red diamonds are somewhat mysterious to researchers, as the cause of their colouration remains yet unknown. Moreover, as only a handful of stones are known, they remain the holy grail of natural coloured diamonds; the largest ever red diamond, the 5.11ct Moussaieff Red diamond, was discovered in Brazil in 1990 and bought by Moussaieff Jewellers in the early 2000s for an estimated $8,000,000.

Other Notable Coloured Diamonds

There are several other varieties of coloured diamonds, however because of their rarity and the fact that they are mostly sold at tender, it is difficult to place a value on them. One interesting example is the chameleon diamond, a diamond which changes colour when exposed to extreme heat or UV light, which is exceedingly unusual but seldom comes to market. 

Read more: The Geology of Diamonds

Grey diamonds gain their colour through hydrogen impurities. Although they are extremely rare, the very fact that they are so unusual means that they have not attracted a great deal of public awareness and have no substantial market desirability. Likewise, violet diamonds are exceptionally rare and hard to value. One of the oldest types of diamonds (type 1 AB), they typically only appear in sizes up to a maximum of 0.25ct and as such larger stones make particularly special finds.

Argyle Isla 1.14 carat radiant shaped Fancy Red Rio Tinto Gem A BlogThe Argyle Isla - a 1.14 carat radiant shaped fancy red diamond. Image courtesy of Rio Tinto. 

As with red diamonds, orange diamonds are very unusual and the origination of their colour has not yet been discovered. The largest ever orange diamond, a 14.82ct pear-shaped fancy vivid orange, stunned at Christie’s in 2013 when it sold for CHF 32,645,000, over double its lower estimate.

By contrast, although white (not clear, but diamonds with a milky-white tone) and black diamonds are quite rare, they have not managed to capture the favour and attention of the public and are considered to be the least valuable of all coloured diamonds.

Interested in furthering your knowledge about diamonds? Find out about Gem-A's Diamond Diploma and Workshops here.

Cover image: Fancy colour diamonds from the Aurora Pyramid of Hope collection - rough and polished diamonds. Copyright Aurora Gems. Photo by Robert Weldon.

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How to Identify Antique Edwardian Jewellery

Understanding how to identify jewellery from different eras and design movements is essential for historians, valuers and antique collectors. Here, Starla Turner FGA GG offers us a glimpse into the refined and elegant world of Edwardian jewellery and describes the motifs that make pieces recognisable. 

Fashion of the Edwardian Era

The short reign of King Edward VII (1901 to 1910), his court, his sporting lifestyle and his wife Alexandra of Denmark were a breath of fresh air to fashion at the close of the 1800s. Jewellery motifs changed accordingly, with intricate and gracefully symmetrical, diamond-encrusted and lacy designs adorning the neckline, chiffon gowns and the ‘up-do’ hair styles of the well-to-do. Delicate scrolls, leaves, ribbon bows, hearts, circles, swooping swags (or garlands as they were later called), and veil-like twinkling jewellery complimented a new sophisticated style.

To me, Edwardian designs look like a frozen moment – curled in movement, shimmering, draping, scrolling, swaging, circling – just waiting to be worn and move again. The Edwardian femininity, fluidity, and fineness are unmistakeable. Iconic pieces have hinges, dangles, swags, articulation, and tiny swinging gemstone droplets evoking a liquidity and liveliness.

Queen Alexandra loved the uncomfortable but fashionable ‘dog collar’ plaque style necklace, often backed by black velvet. The style transitioned into a column of 6-16 rows of pearls — a challenge to wear for sure. Changing dress necklines brought changing neck ornamentation. A good example is the rivière necklace – a neck-encircling strand of graduating, millegraine-edged, bezel set diamonds — sometimes worn as two bracelets.

Read more: The Tale of the Mouawad-Tereschenko Blue Diamond

We see up to 72-inch long strands of ‘spectacle set’ diamonds, a minimalist technique where only a thin wire wraps the diamond girdle and small side jump rings attach to the next gem. The lavaliere is an articulating drop suspended from a matching design element and attached directly to a thin, fancy link chain. The negligee necklace has two drops, often on different lengths of chain, attached to one design element and a simple chain. Basic pendants have diamond-set, double side engraved, tapered bales that hang on thin, intricately designed chains.

Tiaras of the Edwardian Era 

The Edwardian era also saw a fascination with tiaras. Bandeaus, like tiaras, could double as necklaces or bracelets — screw holes or extra loops in the backside show their transitioning versatility. Sautoirs, long bundles of pearl strands ending with tassels, were wrapped around necks, waists, bodices and arms. Bracelets show symmetrical repeating designs in either full length or top half only designs. A new trend was the more diminutive, tapering diamond and coloured stone bracelets with articulating or stretching metal links in the rear. Rings were becoming wider and domed just enough to accommodate the depth of the centre diamond.Edwardian Swan Brooch Back by Lang Antiques Gem A Blog Antique Jewellery VintageThe back of a beautiful swan pin, showing calibré cut emeralds and the 'swinging' diamonds typical of the Edwardian era. 

The Rise of Platinum in Edwardian Jewellery 

Solid platinum or platinum over gold suited the pale, pastel and feminine fashion palette. Platinum was a new white metal that, unlike silver, didn’t stain the skin and clothing and could strongly, but delicately, hold the all-important diamond. Initially, platinum was bonded to yellow gold, a technique created to add value and acceptability to this new, inexpensive and unappreciated metal.

The vast majority of Edwardian diamond pieces I see are hand-fabricated (cut, sawn, rolled, drawn and assembled). Cast pieces are uncommon due to the high heat required to melt the metal. Edwardian jewellery is typically assembled from fewer parts, likely due to the visibility of the yellow gold-based solder that was used.

Read more: The Fascinating History of Platinum Jewellery 

This yellowish solder in seams disappeared into a whiter hue after WWI when white gold made its debut. In addition, platinum is a noble metal – it does not tarnish – so the tarnish one sees is from the solder mix of gold, silver and platinum. Therefore, tarnish and patina can add provenance as it develops with age. Sometimes re-polishing the metal can remove a bit of authenticity.

Diamonds in Edwardian Jewellery 

South Africa supplied a plethora of diamonds. While the Second Boer War (Oct 1899 –May 1902) had an impact on pricing, the demand continued. The diamond circular saw, the fixed dop (the clamp that holds a diamond being cut) for precise angles, bruiting machine advancements and electricity reduced cutting times. They also resulted in the more brilliant, rounder European-cut diamond.

Marquise and pear-shapes also became more available. The beauty of a finished diamond became the focus, rather than the weight retention.

Edwardian Brooch by Lang Antiques Gem A Blog Antique Jewellery VintageAn Edwardian era pin that would have doubled as a tiara or hair ornament. 

Later into the period, single cut diamonds replaced the rose cuts of the past. With faster cutting techniques, the sparkling 17 facet single cut became the perfect accent to delicate jewellery. Smaller Swiss-cut and small European-cut diamonds also help date this era. Old mine cutting was phased out by the end of the era, but diamonds were still recycled into new pieces.

Pearls in Edwardian Jewellery 

Pearls were second to diamond in popularity and suited the monochromatic styling of the era. Their ethereal sheen worked beautifully with gossamer fabrics. Articulating drops gave the appearance of water and added the wonderful element of movement in open work designs. Due to the rarity of natural pearls (cultured pearls were about to debut in high numbers) seed pearls of 3.5mm or smaller were cut into two useable halves and flush mounted onto metal.

Read more: Understanding Diamond Colours with the Aurora Pyramid of Hope 

The American and Scottish freshwater pearls reveal a whiter, wrinkled skin whereas the Indian Ocean and Gulf saltwater pearls are creamy to light grey (often turning grey from a soap that has been used to clean them) and smooth skinned. Uncut and larger natural pearls are often button or oval shaped. The very round cultured pearls in Edwardian pieces tend to be replacement stones.

Gemstones in Edwardian Jewellery 

Sapphire, emerald, opal, ruby, amethyst, demantoid garnet, moonstone or peridots were recessed into a circle of diamonds — enter the halo ring! Look for treasures in these old pieces: Kashmir sapphires, Burmese rubies, Russian demantoid garnets, Australian black opals.

Edwardian Oval Diamond Brooch by Lang Antiques Gem A Blog Antique Jewellery VintageA pierced-out brooch from the Edwardian era.

Calibré cut stones, the tiny (1-2mm), straight-sided, geometrically shaped ruby, sapphire, emerald and amethyst, were cut to fit into channels and dance around designs. The newly-created and evenly-coloured synthetic sapphire and ruby calibré appear in late Edwardian pieces. Black enamel or onyx also provided contrast to the all white look as it transitioned from the mourning jewellery age.

A platinum and diamond central ornamentation could also be highlighted with a larger splash of colour from background bases of pastel toned, transparent to translucent enamels over an engraved gold base — a technique called ‘guilloche’.

Defining Traits of Edwardian Jewellery 

Further defining methods of this era are millegraining and fret work. Overall pieces are finished with delicate, minute beading making the metal disappear into the design. This millegraining took away the sharp edges, softening the look and emphasising the diamond sparkle. Millegraining also enhanced the knife-edged, open, thin wire work called fret work (like the frets for chords on a guitar neck) that created the airiness to the designs and highlighted the incredible expertise of the craftsman.

After WWI the flowing movement of the graceful Edwardian jewellery eventually blended into, and was then lost to, the geometrical, static, anticlassical, architectural style of the Art Deco era — that caught on like fire. Out with the old, and in with the new. 

Follow your passion for gemmology with one of our in-house diamond grading and gemstone workshops

This article was originally published in the Spring 2019 issue of Gems&Jewellery. Gem-A Members can read the issue online, here

Cover image: The front of a beautiful swan pin, showing the calibré cut emeralds and the typical swinging diamonds, all set in platinum. All images courtesy of Cole Bybee and Lang Antiques

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Explore the History of Garnet in Antique Jewellery

Gems&Jewellery is delighted to welcome jewellery historian and valuer, John Benjamin FGA DGA FIRV as our columnist for 2019. As part of a new Gemstone Conversations series, John explores the history of the use of garnet in antique jewellery and tells us why we should give more credit to this special yet undervalued gemstone.

I have often thought that garnet is a rather underappreciated stone. True, it is extremely common and turns up in everything from ancient gold rings to cheap, modern, mass-produced bijouterie — but this misses the point, which is that the sheer beauty and versatility of garnet meant that right up to the beginning of the 20th century it was consistently one of the most popular of all gemstones used in decorative jewellery.

Historic Uses of Garnet in Jewellery

Garnet was esteemed by the Romans at a time when a vivid gemstone conveyed wealth and status. Fine examples were polished into cabochons or cut into cameos and intaglios depicting classical figures or deities. By the 5th and 6th century garnet was often the stone of choice with small, simple, domed or faceted examples providing a decorative embellishment to Anglo Saxon brooches, pendants and buckles.

Neo Renaissance Gold PendantA Neo-Renaissance gold 'Holbeinesque' pendant mounted with a pyrope garnet cabochon in a champlevé enamelled frame set with chrysolites, circa 1870. Image courtesy of Woolley & Wallis.

Garnet Jewellery of the 17th Century 

No doubt because of its widespread availability it was frequently set into medieval rings and ornaments and by the late 16th and 17th century its sheer abundance and desirability led to it being used throughout Europe in everything from rings and earrings to opulent pendants, usually accompanied by colourful, polychrome enamel and gold mounts.

Many of these Renaissance and later garnets were polished into large and irregular-shaped hollow-back cabochons known as ‘carbuncles’ and were usually rich, purplish-red almandines from India and Ceylon. There are quite a large number of these garnets on display in the incomparable Cheapside Hoard at the Museum of London.

Read more: Garnet for those Born in January

For me, part of the allure of garnet is the broad range of colours available and I have always admired hessonites, not only for their rich, orangey-brown colour but also for their interesting ‘treacle-like’ inclusions. Since garnet is a reasonably hard gemstone it provides an excellent cutting surface, so from the 16th to the 18th century hessonite (known in those days as ‘Jacinth’ or ‘Hyacinth’) was a popular stone for fashioning into cameos or setting into bracelet clasps.

The Golden Age of Garnet Jewellery

Undoubtedly, it was the late 18th and early 19th century when garnet really came into its own. Flat-cut almandines of cushion, pear and circular shape were artfully set into parures comprising a necklace, a pair of bracelets, earrings and a brooch. Foiling the stones and fully enclosing the mounts at the back intensified their glowing appearance, especially when illuminated in candlelight.

Georgian Garnet ParureA Georgian gold and flat-cut almandine garnet parure comprising a necklace, earrings, maltese cross and brooch, circa 1800. Image courtesy of Woolley & Wallis.

The use of garnet in moderately priced jewellery continued through the 19th century reaching a peak of popularity in the 1870s when ‘Holbeinesque’ jewellery – pendants and earrings of a design inspired by the look of the Renaissance – resulted in large pyrope cabochons being set in colourful, champlevé-enamelled frames often accompanied by compatible gems such as diamond or chrysolite. This was the so-called ‘Grand Period’ of jewellery manufacture and the rich, vibrant colour of garnet provided the perfect vehicle for showing off bold and distinctive bracelets, brooches and necklaces.

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

Handmade craftsmanship gave way to mechanical, repetitive mass production at the end of the century. Garnet continued to be used in cheap central European jewellery often accompanied by inexpensive colourful gems especially turquoise, pale green beryl and pearls in poor quality, silver gilt settings.

At the same time jewellers in Czechoslovakia (now Czech Republic and Slovakia) began to set clusters of small simply faceted pyropes in base metal thus providing colourful but affordable bangles, brooches and earrings for the mass market. These ‘Bohemian’ garnets are very much of their time and are still very common today.

Bohemian Garnet CrossA 'Bohemian' garnet cross circa 1890. Versatile and inexpensive, these colourful jewels were extremely common at the end of the 19th century. Image courtesy of Woolley & Wallis.

Demantoid Garnet Jewellery 

There was, however, one last moment of glory for garnet. Demantoid, the bright green variety of andradite garnet, had been discovered in the Russian Urals as far back as 1853. Nevertheless, it was not until the 1880s that it started to be set commercially in jewellery and accessories, firstly by Peter Carl Fabergé and subsequently by jewellers in London who obtained supplies from gem merchants such as E W Streeter.

The naturalistic green tones and adamantine lustre of demantoid perfectly conveyed the look of a reptile’s skin or an insect’s body, resulting in a surge of popularity in novelty brooches designed as frogs, lizards and dragonflies. 

Demantoid diamond dragonfly broochA Demantoid garnet and diamond dragonfly brooch, circa 1880. The naturalistic colour of this ever popular variety of andradite garnet resulted in a wide range of novelty insect and reptile brooches appearing on the market at the end of the 19th century. Image courtesy of Woolley & Wallis.

While the more commonplace red varieties of garnet continued to be set in cheap, universally available nine carat gold rings and pendants until the First World War, by the 1920s its use had largely declined and, while it does appear in Post-War ‘Retro’ jewellery and, of course, in modern tsavorite and mandarin garnet rings, the ‘golden years’ of traditional, large scale garnets are now well and truly over. Abundant, often inexpensive and supremely versatile, garnet is surely one of the most underrated of all the better known gemstones. 
If you would like to expand your knowledge on gemstones, find about what Gem-A's Gemmology Foundation and Gemmology Diploma courses have to offer.

This article and images were originally published in the Spring 2019 issue of Gems&Jewellery. Gem-A Members can read the issue here.

Cover Image: Late 18th/early 19th century Neoclassical hessonite cameo ring of the Emperor Tiberius. Images courtesy of Bonhams.

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Gem-A Photographer of the Year Competition Returns for 2019!

We are thrilled to announce that the Gem-A Photographer of the Year competition is back for 2019!

With new rules, a new judging process, and fantastic new prizes, this year’s competition promises to be our biggest and best yet. What’s more, while the competition had traditionally only been open to Gem-A Members and students, we are now happy to accept entries from anyone with an interest in gemmology and a passion for photography.

We are very excited to see what marvels this year’s competition will bring as we have decided to forego categories; instead, we want to see entries that display your own unique interpretation of gemstones, gemmology and the wider trade.

You might decide to share a photograph of a piece of jaw-dropping jewellery, or maybe you have captured the hidden, intricate beauty of a particular gemstone through photomicrography? Or perhaps you have shot a spectacular scene while gemstone mining or trading on a recent trip abroad?

Whatever highlights an unusual or insightful facet of our sector, we want to see it!

2018 Overall Winner - 'Going for the Green': Traders scramble for Myanmar jade at Yangmei's night market in Guangdong Province, China. Image by Richard W. Hughes FGA.

Why Enter?

Win the chance to have your photograph featured in Gems&Jewellery. Winners could be featured on our cover, our Last Impression or our Big Picture feature page.

You can add the accolade of being named Gem-A’s Photographer of the Year to your portfolio.

Entry is free and open to all.

2017 Overall Winner - Dandelion flower in sapphire. Growth blockage with thin film rosette in Sri Lankan sapphire using modified Rheinberg illumination. Field view of 1.34mm. Image by Jonathan Muyal FGA.

The Prize:

The overall winner will be gifted a £300 voucher to spend at Gem-A Instruments and one year’s free Membership of Gem-A.

Two runners up will win a £50 Gem-A Instruments voucher.

All three winning entries will see their photographs published in Gems&Jewellery magazine.

  

2018 Winner - A Persian turquoise dealer presenting a variety of Persian turquoise, temporarily mounted as a ring. Image by Maryam Mastery Salimi.

The competition is open now and we shall be accepting entries until August 30, 2019. The winner will be announced on Gem-A’s Facebook page shortly after the competition has closed.

For the Competition rules and details on how to enter click here. Good luck!

Cover image: 2017 entry - Frog in Amber from the Dominican Republic. Image by Anthony Shih FGA DGA.

Interested in developing your gemmological knowledge? Have a look at our upcoming one-day workshops.

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Buying Guide: Saltwater versus Freshwater Pearls

Treasured the world over for their timeless elegance, lustre and iridescent multi-tonal colours, pearls have been a favourite of high-end jewellers and collectors alike for hundreds of years. 

The majority of gem-quality pearls are produced by bivalve molluscs (an animal whose shell has two hinged parts), but they can also be produced by gastropods (a single shell) which are more rare and may come at a higher price. A pearl is created when an irritant agitates the body of a mollusc and initiates the growth of nacre, a substance that is created by platy crystals of aragonite (a calcium carbonate mineral) held together by an organic compound known as conchiolin.

Well-shaped, naturally occurring specimens can be very rare and highly expensive – in 2017, a natural pearl and diamond drop pendant sold for US$1,452,500 at a Bonhams auction. Cultured saltwater and freshwater pearls are far more abundant and can be cultured to produce excellent lustre in a variety of colours and sizes. But what are the main differences between saltwater and freshwater pearls, and what are the key characteristics that make the highest quality and most desirable specimens?

Saltwater Pearls

Saltwater pearls are produced by oysters found in the sea and generally only a single pearl per shell is found. As natural saltwater pearls are extremely difficult to come across, cultured specimens make up the vast majority on the market. Cultured saltwater pearls are farmed with a bead nucleus made from shells of freshwater molluscs (mussels) as these varieties tend to have thicker shell sections which are ideal for fashioning into a sphere.

3.5-5.9mm Akoya pearls, 3.979cts of diamonds, set in 18ct white gold. From the Yoko London Raindrop Collection. Image courtesy of Yoko London.

Akoya Pearls 

Kokichi Mikimoto perfected the process for culturing pearls in Japan in the 1890s, utilizing Akoya pearl oysters. Akoya pearls are characterised by their very bright lustre and usually white body colour, often enhanced by bleaching. Pink, silver, blue and yellow shades can also occur naturally. Akoya pearls will normally have a diameter of 6-8 millimetres.

Read more: Pearls for Those Born in June 

Grey and black saltwater pearls are highly desirable and have been known to fetch stellar prices at auction. The Cowdray pearl necklace, a string of 42 natural grey saltwater pearls once owned by Viscountess Cowdray, broke the auction record for the sale of a pearl necklace when it sold for US$5.3 million at Sotheby’s Hong Kong in 2015. 

8.5-13.8mm South Sea, Akoya and Tahitian pearls, 18ct white gold clasp. Part of the Yoko London Ombre Collection. Image courtesy of Yoko London.

South Sea Pearls 

South Sea pearls can also be cultured, and although natural specimens would be infinitely more valuable. Cultured South Sea pearls have been known to reach astronomical prices at auction. In 1992 a strand of 23 Australian South Sea pearls sold for $2.3 million at Sotheby’s Geneva. Among the larger of saltwater varieties, they will typically reach 11-14mm in diameter but in some cases they can grow much larger. Part of the desirability of South Sea pearls may be the iridescent gold and silver hues they acquire from the silver-lip and gold-lip molluscs in which they grow.

Tahitian Pearls 

Cultured in a black-lip oyster, Tahitian pearls have a darker nacre with surface iridescence and overtones of peacock, blue, green, purple and gold. Tahitian pearl quality is regulated by the French Polynesian government exerting tight controls to ensure consistent, quality material reaches the market.

12-13mm Tahitian pearl, 0.49ct of diamonds, set in 18ct white gold. From the Yoko London Classic Collection. Image courtesy of Yoko London.

Cortez Pearls 

Originating from rainbow-lipped molluscs found in the Sea of Cortez in Mexico, Cortez Pearls are dark in body colour and display a fabulous rainbow iridescence on the surface. Furthermore, these pearls are somewhat unique as they are the only variety which can show an unusual red fluorescence when exposed to long wave ultra violet light.

Fiji Black Pearls 

Another highly desirable variety of saltwater pearls are Fiji black pearls. Among the rarest types of pearls in the world, they are also a relatively new variety, having first entered the industry in the 1960s. Since then, their introduction by J. Hunter Pearls in 1999 has increased and expanded their market. As a result, we can now see Fiji pearls in a range of vivid colours including gold, peacock, green and chocolate, and although they only have a small yearly output, they command premium prices. 

Freshwater Pearls

Freshwater pearls are grown in rivers and ponds using mussels, and many pearls can be grown within a single shell in a much shorter time that saltwater counterparts. Although freshwater pearls can occur in various colours, white, pink and pastel shades are by far the most common.

There are two ways in which freshwater pearls can be cultured; they can be tissue-nucleated, which means that a small piece of foreign mantle is grafted into the host. This process will usually result in a baroque-shaped pearl.

10-11mm Freshwater pearls, 0.04ct of diamonds, 18ct yellow gold clasp. Part of the Yoko London Classic Collection. Image courtesy of Yoko London.

Cultured freshwater pearls can also be bead-nucleated in the same way as saltwater pearls. Shapes range from round to unique baroques with names like fireball, soufflé and Edison.  However, other shapes are possible, including star, coin and heart. Colour, lustre and size are the most important value factors but they tend to be less lustrous than Akoya pearls.

Considering Value

When considering purchasing freshwater and saltwater pearls, whether natural or cultured, there are five key aesthetic features to take into account in order to make a good investment:

Pearl size

The general rule is the bigger the pearl, the higher the value.

Pearl lustre and orient (shine)

Lustre is a key factor for the majority of cultured pearls and it relates to the amount of light return from the surface of a pearl. Orient is the iridescence of the pearl, a subtle feature created by dispersion of light between platy crystals of aragonite creating different tones.

Pearl colour (shade)

White is a timeless favourite but the value of particular colours is driven by what is popular in fashion at any given time.

Pearl shape

A perfectly spherical shape is always most valuable for pearls.

Pearl surface condition

A near perfect surface condition free from blemishes such as bumps, dimples, scratches and spots will significantly raise the value and market desirability of a freshwater or saltwater pearl.

Read more: Radiocarbon Age Dating on Natural Pearls

While it would always be a very special and rare treat to be able to purchase a set of lustrous, natural round pearls, high quality cultured pearls can make equally, if not more, stunning jewels and a very good investment, particularly when mounted in fine settings from luxury jewellers; exquisite pieces from Harry Winston, Van Cleef & Arpels and Buccellati have recently fetched tens of thousands dollars at auction.

In spite of such awesome prices, the great thing about pearls is that they can be one of the more affordable gemstones to purchase and seem to perennially exude glamour and luxury. If you look out for quality, size, lustre, colour, shape and surface, you are sure to find a fabulous and timeless jewel.

Interested in developing your knowledge about gemstones? Have a look at our upcoming workshops.

Cover Image: 12-13mm South Sea pearls, 0.38ct of diamonds, set in 18ct white gold. Part of the Yoko London Classic Collection. All images courtesy of Yoko London: www.yokolondon.com 

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The History of Queen Victoria's Sapphire and Diamond Coronet

Queen Victoria (1819-1901) famously shared a love of fine jewels and coloured gemstones with her beloved husband, Prince Albert. In fact, one of her most prized possessions - a sapphire and diamond coronet - was designed and commissioned by her husband in 1840. Here, we delve into the story behind this beautiful piece of history.

It is perhaps fated that Queen Victoria’s sapphire and diamond coronet found its permanent home at London's Victoria & Albert Museum in 2019, not least because this year marks the 200th anniversary of the births of both Queen Victoria and Prince Albert. Now, housed within its own cylindrical display cabinet at the heart of the refurbished William and Judith Bollinger Gallery, Queen Victoria’s sapphire and diamond coronet is once again the star of the show. 

The coronet was first acquired by the museum in 2017 and is considered one of Queen Victoria’s most important jewels. It was lovingly designed by her husband, Prince Albert, in 1840 (the royal couple’s wedding year) and was made by jeweller Joseph Kitching.

The coronet is mounted with diamonds set in silver, with 11 step-cut sapphires of octagonal and calf’s head shape, set in gold. The piece was designed to match a sapphire and diamond brooch that Albert gave to Victoria the day before their wedding, perhaps kick-starting the Queen’s love of parures.

In fact, in the same year, she purchased a pair of diamond and sapphire earrings, a brooch and a bracelet of sapphires and diamonds, which suggests she was building a rather impressive matching set!

Read more: What Factors Influence Sapphire Prices?

The design of the coronet was based on the Saxon Rautenkranz – acknowledged as Prince Albert’s coat of arms – although the gemstones are believed to have come from jewellery previously given to Victoria by King William IV and Queen Adelaide.

Prince Albert took a keen interest in Victoria’s jewellery, with one of the Queen’s diary entries from February 1843 stating: “We were very busy looking over various pieces of old jewellery of mine, settling to have some reset, in order to add to my fine ‘parures’. Albert has such taste and arranges everything for me about my jewels.”

 

Queen Victoria, François Forster (1790-1872), Paris, 1846, after Franz Xaver Winterhalter (1805-73). Engraving on paper. © Victoria and Albert Museum, London.

Soon, the coronet was immortalised in influential early paintings of Victoria, including the 1842 official portrait by Franz Xaver Winterhalter, making the sparkling jewel a recognisable symbol of her power and status.

Prior to the untimely death of Prince Albert, Queen Victoria famously had a great love of colourful gemstones and transformable pieces that could be worn in multiple ways. In 1866, she wore the coronet in place of the heavy state crown at the first Opening of Parliament she attended after Albert’s death (perhaps signalling that the piece gave her confidence).

Speaking on the introduction of the coronet to the V&A, senior curator Richard Edgcumbe said: “Queen Victoria’s sapphire and diamond coronet is one of the great jewels of her reign. Designed by Prince Albert, it is an iconic symbol of their love, worn by Victoria as young queen and as widow. We are entirely indebted to William and Judith Bollinger and their sons for the gift of this masterpiece of the jeweller’s art, which is so intimately associated with Victoria and Albert that it will become part of the identity of the V&A.

"Together with an array of eighty new acquisitions and loans made possible by the generosity of many supporters, the display of the coronet inaugurates the next phase in the life of a much-loved gallery.”

All images credit to Jewellery, Rooms 91-93, The William and Judith Bollinger Gallery at the Victoria and Albert Museum (V&A).

This article was originally published in the Summer 2019 issue of Gems&Jewellery.

Thinking of enhancing your knowledge of diamonds? Take a look at our Diamond Diploma and Diamond Grading and Identification course.

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The Famous Diamond Collection of Cardinal Mazarin (1602-1661)

Having successfully completed her Gemmology Diploma and Diamond Diploma, Charlotte Pittel FGA DGA shares an abridged version of her excellent project on Cardinal Jules Mazarin and his legendary love of diamonds.

The Mazarin diamonds were a collection of 18 diamonds left to Louis XIV and the French Crown Jewels by Cardinal Jules Mazarin. Discovering the story of this group of diamonds, the man who collected them and what happened to them is like an incredible work of fiction.

The Life of Cardinal Mazarin

Born Giulio Raimondo Mazzarino on July 14, 1602 to a minor Italian noble family, Mazarin was a man of many interests and talents. His early education was at Jesuit school in Rome before studying law in Madrid. On his return to Rome around 1622 he attended the University of Rome La Sapienza, and following a spiritual awakening he entered the pontifical army.

In 1628 he joined the diplomatic services for the Holy See and became involved in Italian politics whilst working alongside the Cardinals Sachetti and Barberini. His subtlety, patience and hard work were recognised and in 1630, during the war between France and Spain over Mantua, he was sent to negotiate with Cardinal Richelieu.

A bust of Cardinal Jules Mazarin in Paris. Photograph by PlanetKorriban on Flickr (Creative Commons).

Richelieu, impressed with the young man, invited him to Paris where he soon became a confidant and advisor to the Cardinal, joining the court of Louis XIII and Queen Anne d’Autriche. After taking French citizenship he became known as Jules Mazarin and in 1641, was promoted to the rank of Cardinal.

Following Richelieu’s death in 1642, Mazarin succeeded him as the Chief Minister of France and, after the death of Louis XIII in 1643, assisted the Regent Queen Anne in governing France on behalf of her then child son, Louis XIV.

Mazarin was a keen student of the arts, but diamonds were his first love. His collection contained the most beautiful examples, many of them sourced from other European royal families, his preferred jewellers of the time including Lescot, Gabouri, Lopés, and almost certainly from renowned traveller Jean Baptiste Tavernier (1605-1689), who would also supply King Louis XIV.

The 18 Mazarin Diamonds. Illustration inspired by the work of author, Bernard Morel. Image: Charlotte Pittel.

Following his death, Mazarin made generous donations to hospitals, hostels and the arts, and bequeathed his extensive collections of jewellery and gems. Queen Anne received the Rose d’Angleterre (a large round diamond of approximately 14 carats) and a perfect cabochon ruby in a ring.

The Duc d’Orléans received 31 emeralds, while Queen Marie-Thérese was bequeathed a cluster of diamonds. Among his more noteworthy instructions, however, was his wish that a collection of 18 diamonds be given to the King and the Crown of France, on condition that they carry the name Mazarin.

The Famous Mazarin Diamonds

Mazarin assembled this rare and beautiful collection of 18 stones towards the end of his life. Only three of these stones are named: the Sancy, the Mirror of Portugal and the Grand Mazarin. Sadly, due to the tumultuous nature of 18th century French history, many of the 18 stones have disappeared.

An impression of the Mirror of Great Britain, as seen affixed to King James I's hat in a portrait that is housed in the Scottish National Portrait Gallery. Image: Charlotte Pittel.

The Mazarin I — the Sancy Diamond

It is believed that the 106 (old) carat Sancy formed part of the collection of Charles the Bold, Duke of Burgundy. Following his death it disappeared for over 20 years, finally reappearing in Germany in the hands of a merchant banker named Jacob Fugger. He planned to sell the diamond to the King of Portugal, Don Manuel I, and re-cut it into the pear shape we see today.

During a period of huge political upheaval and conflict between England, France, Spain and Portugal, the diamond would finally end up in the collection (and take the name) of Nicholas de Harley, Seigneur de Sancy and Baron de Maule (1546-1629).

De Sancy was made Superintendent of France by Henry IV and pledged his diamonds to raise money for the crown. In 1596, however, he negotiated the sale of the stone to James I of England, who set the Sancy as a pendant into the jewel known as the Mirror of Great Britain.

Read more: Diamond for Those Born in April

James’s successor Charles I sold off precious stones to raise funds for the Royalist cause and, in 1644, sent his consort Queen Henrietta Maria to France to secure supplies and munitions. She borrowed enormous sums from the Duke of Epernon and pledged the Sancy as collateral. In 1649, when Charles I was beheaded, the Queen was exiled. The Sancy diamond was claimed by the Duke and subsequently sold to Cardinal Mazarin.

The Sancy then became part of the French Crown jewels and was mounted in Louis XV’s coronation crown in 1722. Today, the Sancy is on display at the Louvre Museum in Paris.

John de Critz's 1604 portrait of James I shows the King wearing the legendary 'Mirror of Great Britain' jewel. Image: Public Domain.

The Mazarin II Diamond

Author Bernard Morel suggests that this stone could well be the Pinder diamond, based on a 17th century description and drawings made by Thomas Cletscher. Sir Paul Pinder was a businessman and diplomat and, in 1611, James I made him an ambassador to Turkey where he managed to acquire some exceptional jewels, including the Pindar.

Called at this time the Great Diamond, it was acquired by Charles I in 1625 for 18,000 livres but not paid for. It is likely that this is one of the stones pledged by Queen Henrietta Maria in 1646 and then acquired by Mazarin, becoming known as the Second Mazarin.

It was included in a diamond chain worn by Louis XIV, before being re-cut and set into the centre of the Order of the Golden Fleece made by Jacquemin for Louis XV. Thereafter it was unset and remained in the collection of Louis XVIII until his death in 1824, at which time it was returned to the Crown collection. Sadly, the stone was stolen during the 1848 revolution.

The Mazarin III — the Mirror of Portugal Diamond

This stone belonged to Dom Antonio, Prior of Crato. After a short period with Elizabeth I and named the Portugal Diamond, it was mounted into a pendant set with a large pearl drop and given to Henrietta Maria on her betrothal to Charles I. It eventually became a part of the Mazarin Collection.

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

As was the custom, many of the French crown jewels were in settings that allowed a freedom in how they could be worn. As such, the Mirror of Portugal was set not only in Louis XIV’s diamond chain, but also in a hairpin worn by Queen Marie-Thérèse, which also bore the Grand Mazarin and some substantial pearls.

The Third Mazarin was unfortunately lost to the French Crown jewels when a substantial number of the jewels were sent to Constantinople never to return, including the Mirror of Portugal and many other Mazarins.

The Mazarin IV Diamond

This stone was first referenced in Bernard Morel’s book as being set into a pair of Girandole earrings created for Queen Marie-Thérèse. It is shown sitting as the top button with the Mazarin V as a drop. Its pair uses other diamonds, including the Mazarin VI as the drop.

An illustration of Queen Marie-Thérèse's girandole earrings, inspired by the work of Bernard Morel, containing some of the Mazarin diamonds. These earrings were documented in the 1691 inventory of the French Crown Jewels and were valued at 500,000 livres. Image: Charlotte Pittel.

The Mazarin V and VI Diamonds

Both the Mazarin V and Mazarin VI were pierced at the top, so were perfectly shaped to be worn as drop earrings. Records suggest that both of these stones were cut by Francisco Ghiot of Antwerp: 1632 for Mazarin VI and Mazarin V in 1636. In a later inventory of 1774, they show up possibly as rings.

The Mazarin VII — Le Grand Mazarin Diamond

This legendary coloured diamond was sold at Christies on the November 14, 2017, achieving a price of CHF 14,375,000 (approximately GBP £10,969,567.60). A GIA certificate (No. 5182785154) and classification letter confirms that this historic light pink, old-mine brilliant-cut diamond is a Type IIa and weighs approximately 19.07ct.

Read more: The Geology of Diamonds

This diamond can be traced back to Indian mines near the Golconda trading centre, but quite how it came to Cardinal Mazarin is unknown. Once the diamonds were passed to Louis XIV and the Crown Jewels collection, it is believed that Queen Marie-Thérèse was the first to wear it.

Following her death in 1683, Louis regained the Grand Mazarin and added it to his legendary chain of diamonds. It was listed in the 1691 inventory as sitting at number five on a chain of 45 diamonds, numbered in descending order of size. It was added to the crown of Louis XV, along with the Sancy.

The Mazarin VIII Diamond

One of the few diamonds to survive a significant sale in 1795, this Mazarin stone sat at either position six or seven on Louis XIV’s diamond chain. The standout piece in which it featured, along with the Grand Mazarin, was the Diamond Diadem of Marie-Louise, Empress of the French from 1810 to 1814. A large diamond parure was ordered soon after the wedding of the Emperor and Empress, along with a coronet, a necklace, pair of bracelets, girandole earrings and a belt. There was also an order for a substantial diadem.

An impression of Empress Eugénie's reliquary brooch designed and created by Alfred and Frederic Bapst in 1855. It was sold to the Louvre Museum in Paris in 1887. Image: Charlotte Pittel.

The Mazarin IX Diamond

Originally described as boat-shaped, the term ‘marquise’ was coined during the reign of Louis XV, largely due to a rumour that it matched the lip shape of his mistress, Madame Marquise de Pompadour. This diamond was set as the eighth button on one of Louis XIV’s justacorps (an open-fitted coat).

The Mazarin X — XVI Diamonds

Along with others, these diamonds were also included in the diamond chain belonging to Louis XIV and also in the coronation crown of Louis XV. The Mazarin XII was described as having a red colouration, probably due to the reddish flaw in its girdle.

The Mazarin XVII-XVIII Diamonds

The last two stones of the collection - XVII and XVIII - were virtually identical, with XVIII slightly larger. It seems that these stones were kept as a pair and used as buttons on a coat belonging to Louis XIV. They are most famed for being part of Empress Eugénie's reliquary brooch of 1855, now part of the collection at the Louvre.

The Mazarin Cut

It should be noted that none of the 18 diamonds that Cardinal Mazarin bequeathed to Louis XIV were cut in the ‘Mazarin cut’. Instead, the cuts were as follows:

  1. Pear-shape double rose cuts — I (Sancy), V and VI
  2. Rectangular table cuts — II (Mirror of Portugal), III, IV
  3. Square table cuts — VII (Grand Mazarin), VIII, X, XI, XII, XIII, XV, XVI
  4. Heart-shape flat rose cuts — XVII, XVIII
  5. Marquise — IX

The fashioning of diamonds in 17th century Europe was undeveloped. Until the 1400s the natural form of the diamond was used, so an octahedral crystal or other rough was refined and set (known as the ‘point cut’). The table cut was first seen around 1477, marking the first true cut where the octahedron crystal had its top flattened by grinding and sometimes a culet added to the lower point. Varieties of the table cut are the thick table cut, the mirror cut, the tablet and the lasque cut.

A representation of the Mazarin Cut, inspired by the drawings and insights of Eric Bruton and Herbert Tillander. Image: Charlotte Pittel.

After the table cut followed rose-cut stones; a flat backed stone with a domed front. There were a variety of rose-cut styles in use at the beginning of the 15th century and it was considered the most appropriate cut for a flatter, thinner stone. Early brilliant cuts were first seen in the mid- 1600s, leading us back to the diamond-loving Cardinal Mazarin.

Single-cut or eight-cut diamonds had eight facets on the table and eight facets on the pavilion plus a culet. These then evolved into the double, cut with 16 facets on the table and 16 facets on the pavilion plus a culet.

It was in the mid-17th century that the Mazarin cut appeared, cushion-shaped with 34 facets in total: 17 facets on the table and 17 facets on the pavilion, including the culet, plus a girdle. This design of facets greatly increased the diamond’s reflective properties and it showed more fire and brilliance.

Although Mazarin was a devoted diamond collector, it is unlikely that he actually invented the Mazarin cut. However, he was a definite forerunner in the rise of popularity for this style of cutting and it is most likely that the cut was named after him as a tribute.

The complete version of this project, including references, appendices and a bibliography are available upon request. All images and illustrations are supplied by the author unless otherwise stated.

This article was originally published in the Spring 2019 issue of Gems&Jewellery.

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Understanding Tanzanite

Delve into the Gem-A Gemstone & Mineral Collection and you will find this fantastic cut tanzanite and rough tanzanite crystal specimen (pictured above). Here, Gem-A gemmology tutor, Charles Bexfield FGA, explores what makes this relatively new gemmological discovery so special. 

Found in 1967 at the foothills of Mount Kilimanjaro, tanzanite is a relatively new stone and is the purplish blue variety of zoisite. Zoisite is a species of gemstones which share the same chemical composition; zoisite’s composition is calcium aluminium silicate with hydroxyl.

Read more: Why Tanzanite is the Birthstone of December

Today, tanzanite can only be found in the Merelani Hills of Tanzania. A year after its initial discovery it was named after the country in which it was found and introduced to the market by Tiffany & Co., who transformed this previously unknown gemstone into a highly fashionable jewel. Testament to this stone’s huge popularity, in 2002 tanzanite became adopted as a new birthstone for December by the American Gem Trade Association (AGTA).

The Natural Availability of Tanzanite

Tanzanite is a relatively abundant gemstone. Based on a study conducted by TanzaniteOne Mining Ltd in 2012, 270 million carats are mined per year, which equates to 54 tonnes. The current projections suggest the mines will continue to produce gem quality material at the same rate for another 23 years, providing they can progressively dig deeper and reach all the potential material remaining.

Zoisite rough crystal and facetted gemstone Tanzanite Gem A Blog GemA HMA pear-cut zoisite alongside a rough zoisite crystal. Image: Gem-A.

Currently, there are four main commercial mines for tanzanite in Tanzania, separated into blocks A, B, C and D. Each block is owned by a different company; the case study above was carried out on block C, which is by far the largest block on the site, being bigger than the other three mines combined.

Tanzanite Colour and Structure

Tanzanite gains its distinctive purplish blue colour from the trace elements of vanadium and chromium present within its structure. Tanzanite shows very strong pleochroism, which is an optical property and a term used by gemmologists to describe different colours seen in the same material when viewed from different directions. The pleochroism in tanzanite is so strong it is visible by just turning the stone and viewing it through different directions without the aid of a dichroscope.

Tanzanite Pleochroism Gem A BlogPleochroism in tanzanite. Image by Pat Daly FGA.

Providing tanzanite has not been heat-treated, it will show three pleochroic colours: red-violet, deep blue and a greenish yellow. However, if heated above circa 400°C to 500°C, the greenish yellow colour is removed or substantially reduced and the bluish colour deepens.

Read more: What Are the Most Important Gemstone Producing Countries?

The vast majority of tanzanite on the market today is heat-treated to enhance its colour and marketability. Indeed, tanzanite has proven to be a favourite of the rich and famous in recent years, with celebrities such as Beyoncé, Sarah Jessica Parker and Penelope Cruz having been pictured wearing the gem. The Duchess of Cambridge has also on many occasions been spotted wearing a matching set of pear-cut tanzanite earrings and necklace. 

A faceted tanzanite displaying the stone’s distinctive purplish blue colour. Image: Gem-A.

Currently there is no known method for creating synthetic tanzanite. But keep an eye out for synthetic forsterite, which can be used as convincing simulant at first glance. Like tanzanite, it is also strongly pleochroic, however the colours seen when viewed in the different directions are vivid blue and purple, which helps to differentiate between the two stones.

The Value of Tanzanite

On average tanzanite is quite an expensive gemstone; specimens weighing one carat or less will reach prices of about £225 to £250 per carat. Most faceted tanzanite seen commercially on the market is below five carats, while faceted stones over 30 carats are more seldom seen.

The average price of good quality, untreated tanzanite over five carats is about £900 to £1,100 per carat, while smaller sizes around two to three carats can achieve prices of between £350 to £580 per carat. With this in mind, prices do vary depending on colour and treatments, as well as on the particular suppliers or retailers from which you choose to purchase.

Read more: What Makes a Gemstone Rare?

Tanzanite crystals are usually prismatic and quite well formed; any crystals over 50 carats are considered large and are usually sold to mineral or crystal collectors rather than being cut. The largest piece of tanzanite rough reported in the press was found in 2005 by TanzaniteOne Mining Ltd, weighing in at 16,839 carats (7.43lbs or 3.37kg) and measuring approximately 21.8cm x 8cm x 7.11cm, making it a hugely impressive specimen. 

 

An example of a large rough tanzanite crystal. Image by Pat Daly FGA.

However, the largest tanzanite ever sold at auction is the 423.56 Namunyak Tanzanite, which was set into an 18-carat white gold necklace accompanied by 53 carats of diamonds by jewellery designer Kat Florence; the piece fetched over $300,000 USD at a charity sale in 2016 to raise funds for victims of the Nepal earthquake in 2015.

Tanzanite Buying Advice

Before purchasing a piece of tanzanite jewellery it is important to bear in mind that tanzanite measures between 6 to 7 on the Mohs scale and therefore is not a particularly hard stone. As such, tanzanite can be more liable to scratches and damage and consequently may not be the most suitable stone for wearing as an everyday ring.

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

If you decide to buy a tanzanite use a 10x loupe to examine the cut, clarity and any presence of chips or cracks. It is also advisable to compare a number of stones to gauge the hue and saturation of colour. By taking these short steps you can better ensure that you will walk away with a good quality tanzanite specimen.

Discover more incredible specimens in the Gem-A Gemstone & Mineral Collection, including sugilitestibnite and decorative fossils.

Start your gemmology journey today with the Gem-A Gemmology Foundation course or one of our many Short Courses and Workshops. Contact education@gem-a.com to find out more.

Cover image: Rough and polished tanzanites from the Gem-A Collection, photographed by Henry Mesa. 

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The Gems&Jewellery Autumn 2019 Issue Has Landed!

We are pleased to announce that the Autumn 2019 issue of Gems&Jewellery is now available to Gem-A Members and students in print and online.

Our quarterly magazine includes exciting updates from the world of gemstones and jewellery, as well as interviews and features from industry experts and the latest Gem-A news.

The Autumn issue begins with our CEO Alan Hart looking ahead to some of the most anticipated events in Gem-A’s calendar, including International Jewellery London, the Hong Kong Jewellery & Gem Fair and of course the Gem-A Conference 2019! Turn to page 16 for an exclusive preview of the brilliant line-up of speakers and talks planned for this year’s Conference.

An opal mine in Queensland, Australia. Image: Barbara Kolator.

On page 10 you can read Olga González’ highlights of Las Vegas’ jewellery and gem shows in June, which included Couture, JCK and AGTA GemFair. The shows may have been a departure from the norm, but the jewellery was bigger and better than ever. You can see some sparkling and inspiring examples from Valani Atelier, Lord Jewellery and L. Courteille Créations on pages 10 and 11.

Turn to page 12 to go on a journey through the Australian Outback with Gem-A collection curator, Barbara Kolator FGA DGA EG. Her account includes tales of visiting opal mines, sifting for sapphires and gemstone shopping!

Read more: What Are the Different Types of Opal?

Celebrated gemmologist and author, Renée Newman GG, tells us why we should consider redefining the 4Cs of diamonds and proposes a new system '6Cs and 2Ts' on pages 20-21. Directly following on page 22, we delve into the famous Al Thani Collection of treasures, including the 400 pieces recently sold by Christie's, and turn to jewellery historian Jack Ogden FGA for his expert opinions.  

Moonflower Sanni Falkenberg Gem A Gems Jewellery Autumn 2019 issueSanni Falkenberg's Award-Winning Agate 'Moonflower' Vase. Image: Sanni Falkenberg.

Elsewhere, Brighton-based lapidary artist Sanni Falkenberg takes us through the step-by-step process of creating her agate ‘Moonflower’ vase, which won gold at the Goldsmiths’ Craft & Design Council Awards 2019, while over on page 44, we bring you all the essential information – including the brilliant prizes up for grabs – about this year’s Gem-A Photographer of the Year Competition!

Read more: What Factors Influence Sapphire Prices?

The striking cover photo from this season’s issue features the astounding 'Siren of Serendip' sapphire set in a white gold and diamond necklace. On page 36, Rui Galopim de Carvalho FGA DGA reports on the origins of this 422.66 carat gem and the process of transforming it into a magnificent piece of jewellery.

A Turn of the century gold necklace set with turquoises, turquoise matrix and blister pearls designed by Archibald Knox for Liberty & Co. Image courtesy of Charlotte Glyde at Woolley and Wallis.

Jewellery historian and valuer John Benjamin FGA DGA FIRV brings us the next instalment in his Gemstone Conversations series with an exploration of the various faces of turquoise in jewellery design history, from the courts of the Shahs of Persia to the cutting-edge jewels of the Art Deco era. To round off our issue, we look back on our visit to JCK and AGTA GemFair in Las Vegas and let you know where we are heading next!

If that wasn’t enough, this issue also features articles on jewellery designer Sarah Ho’s new Full Circle Collection; the interesting career and upcoming projects of Belgian jewellery designer Jochen Leën; tortoiseshell trading confusion; a Gem-A student project on ‘The Importance of Jade in the Mughal Court’; and a quick introduction of the Ivory Act.

Gem-A Members and students can access a PDF version of Gems&Jewellery here. Simply access the archive with your log-in details. 

Would you like to receive print editions of Gems&Jewellery and The Journal of Gemmology straight to your door? Become a Gem-A Member today.

Do you have an idea for an upcoming Gems&Jewellery feature? Share your thoughts with our editorial team on editor@gem-a.com.

Cover image: The 422.66 carat Siren of Serendip blue sapphire set in a white gold and diamond necklace by jeweller Ingo Henn. Image courtesy of the Houston Museum of Natural Science.

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アンティークのエドワーディアン・ジュエリーの見分け方

 

歴史家、査定人、アンティーク・コレクターにとって、様々な時代やデザインの流行からジュエリーを見分けることは必要不可欠です。ステラ・ターナー FGA GGが、上品で洗練されたエドワーディアン・ジュエリーの世界を紹介し、この時代に特徴的なモチーフについて解説します。  

短かったエドワード7世の治世(1901~1910年)、宮廷ではエドワード王が好んだスポーツを中心としたライフスタイルとデンマーク出身のアレクサンドラ王妃の存在が、1800年代の終わりの流行に新しい風を吹き込みました。それに伴ってジュエリーのモチーフは変化を遂げました。ダイヤモンドを散りばめ、複雑、優雅で均整の取れたレースのようなデザインが流行し、ネックラインや、裕福なシフォンのガウンと「結い上げた」ヘアー・スタイルを飾るようになりました。繊細なスクロール、葉、リボン、ハート、サークル、揺れる垂れ飾り(あるいは、後述するガーランド)、そしてベールのように軽やかなジュエリーは、洗練された新しいスタイルを称えるものでした。

私にとって、エドワード時代のデザインは「凍った瞬間」のように見えます-渦巻き状の動き、かすかな輝き、ゆるやかなドレープ、スクロール、そして揺れ動き、円を描く-それは、ジュエリーが身に着けられ、再び動く時を待つかのようです。エドワード時代の女性らしさ、流動性、繊細さがデザインによく表れています。この時代のジュエリーは基本的に、蝶番、垂れ飾り、花綱、動きを出す構造、流動性、小さく揺れ動く宝石でできた滴で構成されています。

アレクサンドラ王妃は、着け心地はいまいちでありながらも、ファッション性に富み、装飾を施したプラーク(板)のついた「ドッグ・カラー」ネックレスを好み、黒いベルベットを付けて愛用しました。そして、このスタイルは後に6-16列に並べた真珠へと形を変えました-身に着けるのが難しいものです。ドレスのネックラインが変わると、首周りの装飾品にも変化をもたらしました。例として挙げられるのは、リヴィエール・ネックレス-ミルグレイン(ミル打ち)で縁取られた覆輪留めのダイヤモンドが一周したグラデーションの付いた連-であり、これは二本のブレスレットとして着用されることもあります。

ダイヤモンドに「スペクタクル・セット」を施した最長72インチの長い連のネックレスもあります。これは細いワイヤーでダイヤモンドのガードル部分を巻き、脇についた小さな丸カンを隣の宝石につなぐというシンプルな技法です。またラヴァリエールは、デザインが同じパーツから滴状の飾りが下がるように、装飾を施した細い鎖で繋いだネックレスです。ネグリジェ・ネックレスは、二つの飾りが時折異なる長さのシンプルなチェーンで一つのデザイン・パーツからぶら下がったものです。通常、ペンダント(ぶら下がる部分)には、ダイヤモンドがセットされ、彫刻や次第に先が細くなった飾りがあり、繊細にデザインされたチェーンで繋がれています。

ティアラもまたエドワード時代の興味深いジュエリーです。ティアラに似たバンドーはネックレスやブレスレットにも使用することができます-後部にあるネジ穴またはループは、形を変えることができる融通性を示しています。長い真珠の連を束ね、先端にタッセル(飾り房)の付いたソートワールは、首、腰、ボディス(肩からウエストまで)、腕に巻き付けて装いました。ブレスレットには、一周、または上部半周を対称的に繰り返すデザインが用いられました。新しい流行は、先が細くなるデザインをつけた小さなダイヤモンドや色石のブレスレットで、後ろ側で連結金具を繋いだものでした。リングは中央のダイヤモンドの深さが十分に収まるように幅が広くドーム状になりました。

Edwardian Swan Brooch Back by Lang Antiques Gem A Blog Antique Jewellery Vintage美しい白鳥のピンの裏側。エドワード時代に典型的なカリブレ・カットのエメラルドと「スウィングする」ダイヤモンド。

堅いプラチナまたはプラチナを付けたゴールドは、淡くやわらかい女性らしいファッションの色調によく合いました。プラチナは新しい白い金属で、シルバーとは異なり、肌や衣服を汚すことなく、強度があり、最も重要なダイヤモンドを繊細に留めることができました。当初、プラチナはイエロー・ゴールドに接着されました。この技術は新しく、高価でない、価値が認められていない金属に付加価値をもたらしました。

私が見てきたエドワード時代のダイヤモンド・ジュエリーの大多数は、手作り(カット、切断、引き延ばし、引き絞り、組み立て)の作品です。金属を溶かすのには高温を必要とするため、キャストで作ったものは一般的ではありません。イエロー・ゴールドをベースとしたロウを使用しているのが見えてしまうので、エドワーディアン・ジュエリーは通常少ないパーツで組み立てられています。

金属の継ぎ目に見られる黄色味を帯びたロウは、ホワイト・ゴールドが作られるようになった第二次世界大戦後には、白色に近くなり、姿を消しました。さらに、プラチナは素晴らしい金属で-変色しません-変色が見られる場合には、ゴールド、シルバー、プラチナを混合したロウが用いられています。変色や錆は年月が経つにつれて生じるため、そのジュエリーが古いものであることがわかります。金属の磨きなおしは、時に古いものである証拠を取り除いてしまうことがあります。

当時、南アフリカは大量のダイヤモンドを供給していました。第二次ボーア戦争(1899年10月-1902年5月)はダイヤモンドの価格に影響を及ぼしましたが、需要は伸び続けました。この頃になると、ダイヤモンド用の丸い鋸、正確な角度をつけるための固定したドップ(カットするダイヤモンドを保持する締め金)、ブルーティング用の機械の向上と電気によって、カッティングに要する時間を削減しました。これはまた、より輝くラウンド・ヨーロピアン・カットのダイヤモンドを生むことにもなり、マーキーズやペア・シェイプも入手しやすくなりました。そして、カットの際には重量の保持よりも仕上げたダイヤモンドの美しさに焦点を当てるようになりました。

Edwardian Brooch by Lang Antiques Gem A Blog Antique Jewellery Vintageティアラにもヘア・オーナメントにもなるエドワード時代のピン。

後の時代にはシングル・カットのダイヤモンドが過去のローズ・カットに取って代わります。ダイヤモンドを早くカットできるようになり、煌めく17面をもつシングル・カットは、繊細なジュエリーを上手く引き立てることとなりました。小さなスイス・カットとヨーロピアン・カットのダイヤモンドは時代を見分けるのにも役立ちます。エドワード時代の終わりには、オールド・マイン・カットは無くなりましたが、このカットのダイヤモンドは、今もなお新しいジュエリーに再利用されています。

真珠はダイヤモンドに次ぎ二番目に人気があり、エドワード時代のモノクロのスタイルに合っていました。真珠の優美な光沢は、薄手のファブリックと組み合わせると美しく映えました。ぶら下がった滴状の飾りは、まるで水のようにオープン・ワークのデザインに素晴らしい動きの要素を加えました。天然真珠(この時まさに、養殖真珠はかなりの数が市場に登場するところでした)は稀少であったため、3.5mmのシード・パールまたはそれより小さいものは半分で使えるようにカットされ、金属にセットされました。

インド洋やペルシャ湾の海水産真珠はクリーム色~明るいグレー(洗浄に使用する洗剤でグレーになることがあります)で滑らかな表面であるのに対し、アメリカとスコットランドの淡水真珠は白くしわが寄っています。カットしていない大きい天然真珠は、時にボタン型やオーバル型の形状をしています。真円養殖真珠がエドワーディアン・ジュエリーに見られる場合、この真珠は既に取り換えられたものの可能性があります。サファイア、エメラルド、オパール、ルビー、アメシスト、デマントイド・ガーネット、ムーンストーン、ペリドットといった宝石は、周囲を複数のダイヤモンドで飾ったリングに仕立てます-これは、ヘイロー・リングと呼ばれるものです!カシミール産サファイア、ビルマ産ルビー、ロシア産デマントイド・ガーネット、オーストラリア産ブラック・オパールなど、古いジュエリーから宝物を見つけてみましょう。

Edwardian Oval Diamond Brooch by Lang Antiques Gem A Blog Antique Jewellery Vintageエドワード時代の透かし細工のブローチ

とても小さく(1-2mm)真っ直ぐな面をもつ幾何学的な形状のルビー、サファイア、エメラルド、アメシストは、チャンネル・セッティングに合うようにカットされたもので、このカリブレ・カット石はデザインに沿ってセットしていきます。新しく作られた均一な色の合成サファイアやルビーのカリブレ石はエドワード時代後期のジュエリーに見られます。ブラック・エナメルまたはオニキスは、モーニング(喪)・ジュエリーの時代が終わりを迎え、真っ白な見た目にコントラストを与えるものとして使用されました。

プラチナとダイヤモンドでできた中央の装飾は、淡い色の背景によって強調されます。この背景は彫刻したゴールドの土台に透明から半透明のエナメルを施したもので、「ギヨシェ」という技法です。

他にもこの時代の技法にはミルグレインと透かし細工があります。ジュエリー全体が繊細に仕上がり、微小なビーディング加工により金属がデザインに溶け込みます。このミルグレインは鋭い縁を取り除き、滑らかな見た目を作り、ダイヤモンドのきらめきを強調する効果があります。またミルグレインは、透かし細工(ギター・ネックの弦の格子模様のような)と呼ばれるナイフ・エッジのオープン・ワイヤー・ワークをも引き立てます。この細工はデザインに軽やかさを生み、職人の驚くべき専門的技術が際立つものです。

第二次世界大戦後、上品なエドワーディアン・ジュエリーの流行は、最終的にアール・デコの幾何学的、静的、反古典的、建築的スタイルに融合して消えていきました- このアール・デコ・スタイルは瞬く間に人気を博しました。古いものを捨て、新しいものを取り込んだのです。  

Gem-Aのダイヤモンド・グレーディングと宝石のワークショップに興味がある方は、こちらをご覧ください。

この記事は「Gems&Jewellery」Spring 2019号に掲載されたものです。Gem-A会員の方はこちらのオンラインからもご覧いただけます

表紙の写真:美しい白鳥のピン(正面)。プラチナにセットされたカリブレ・カットのダイヤモンドと「スウィングする」ダイヤモンド。写真提供:Cole Bybee and Lang Antiques。

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