The History, Heritage and Hype behind Golconda Diamonds
Renowned jewellery historian and published author, Jack Ogden FGA, traces the history of Indian diamonds and questions the sustained marketing hype around the famous Golconda mines. Today India is the largest centre for diamond cutting, handling some 90 percent of the world’s diamonds. But most who cut, sell or buy these diamonds, in the cutting […]
Understanding Specific Gravity and Why it is Vital to Gemmologists
Specific Gravity is a vital test that all gemmologists need to be aware of. Here, Gem-A Gemmology Tutor, Dr Juliette Hibou FGA, explains the concept of specific gravity and how it is used by gemmologists to aid in gemstone identification. Different gemstones have different densities; this property is used to differentiate between materials. In gemmology, we […]
American Gemstones: Benitoite from California
In 1907, by the headwaters of California’s San Benito River, a new blue gemstone was discovered which was to be named benitoite. Here, Elizabeth A. Gass FGA, Gemstone Advancement and Education Coordinator at Jewelry Television (JTV), takes a closer look at this all-American gemstone. The United States is a geographically vast and geologically diverse nation. […]
Historic Uses of Topaz Gemstones in Jewellery
Jewellery historian and valuer, John Benjamin FGA DGA FIRV, shares insights into the history of topaz gemstones in jewellery, including its symbolism, fluctuating popularity and evolving style. Topaz is one of the most elegant and subtle of gems. I studied first year gemmology in the early 1970s. Our excellent tutor, Denis Inkersole, invited the class […]
American Gemstones: Red Beryl from Utah
One of the rarest gemstonesto be found in the United States – and indeed the world – is red beryl. Here, Elizabeth A. Gass, Gemstone Advancement and Education Coordinator at Jewelry Television (JTV), explores the mining history and natural origins of this special red gem. Many mineral discoveries in the US were made by those in search of the ‘mother lode’ but instead miners found themselves looking at something totally […]
American Gemstones: Sweet Home Mine Rhodochrosite from Colorado
Rhodochrosite can be found in various locations across the world however the most iconic variety is widely agreed to be from the Sweet Home Mine in Colorado. Elizabeth A. Gass, Gemstone Advancement and Education Coordinator at Jewelry Television (JTV), takes us through the history of rhodochrosite mining at the Sweet Home Mine and explores the legendary status acquired by […]
American Gemstones: Yogo Sapphires from Montana
Native to Montana, the sought-after Yogo sapphire was first discovered accidentally by a gold miner in the 1890s. Elizabeth A. Gass FGA, a Gemstone Advancement and Education Coordinator at JTV, guides us through the gemmology and origins of the Yogo sapphire and explains what makes this dazzling American gem so special. Montana has so much mineral wealth that one of its nicknames […]
The Famous Diamond Collection of Harry Winston
“Talk to me, Harry Winston, tell me all about it!” That’s just one of the immortal lines from Diamonds are a Girl’s Best Friend, sung by Marilyn Monroe… and it turns out the renowned American jewellery house has plenty to say, especially when it comes to extraordinary gemstones. With the nickname ‘the King of Diamonds,’ […]
Understanding Play of Colour and Patterns in Opal Gemstones
Did you know the colours and patterns in an individual opal gemstone can drastically alter its value and desirability? Here, Gem-A Gemmology and Diamond Tutor, Charles Bexfield FGA DGA EG offers an overview of the play of colour and patterns to look out for in the finest opal gemstones. Opal is an amorphous hydro-silicate SiO2·H2O […]
What Does It Mean When a Specimen Is Opalised?
Senior Gemmology Tutor Pat Daly FGA DGA explores the phenomenon of opalisation, how it occurs and where you can expect to find opalised specimens. Most gem quality opal forms in sedimentary rocks, as it does in Australia, for example. Many of these were marine or lake sediments within which shells, bones and wood were sometimes […]
