Chameleon diamonds have an unusual ability to change colour temporarily, either when gently heated to approximately 150 C (thermochromism) or after prolonged storage in the dark (photochroism).
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Natural near-colourless diamonds originate from more than 10 diamond-producing nations whose mines are owned by several big mining companies, including major players like Alrosa, Dominion Diamond Corp., De Beers, and Rio Tinto.
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In the last few years, several high-profile incidents of parcels salted with synthetic diamonds have put the industry on high alert. They have also spurred gemmologists and others to develop new tools for identifying lab-grown stones.
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When tribesmen in Tanzania first presented violet crystals to trader Manuel de Souza in 1967, he didn’t realize what they’d discovered was a new gemstone. Instead, he believed he was looking at unusually coloured sapphires.
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One in 10,000 natural diamonds has enough colour to be deemed a fancy-coloured stone. Browns are the most common, and some mines like Rio Tinto’s Argyle in Australia produce large quantities of these diamonds, which are marketed as ‘champagne’ in the lighter yellowish brown range and ‘cognac’ for the darker orangey brown variety.
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“What’s in a name? That which we call a rose by any other name would smell as sweet.” It is clear Shakespeare placed more emphasis on what something is, rather than what it is called. Yet, when it comes to gemmology and provenance, it would appear the lines are slightly blurry.
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Jade is a commercial term encompassing green, white, black, and yellow-brown jadeite and nephrite. The world nephrite jade market is estimated at more than 1000 tonnes per year, with half the supply originating from British Columbia.
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Smithsonian Museum curator Jeffrey Post will deliver the keynote address at the 22nd annual Canadian Gemmological Association (CGA) Conference in Vancouver.
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