Just an Old Lump of Coal?

SSEF, the Swiss Gemmological Institute, recently changed its certification of black diamond. According to lab director Prof. Henry Hänni, large quantities of black diamonds in all sizes are being created by cooking ordinary crushing bort at high temperatures. The black bort is then cut and polished for use in trendy black diamond jewelry. Heated black diamond appears similar to naturally colored black diamond. Rahul and Sunil Karnavat of Lotus Diagems in New York, specialists in irradiated blacks and other color-enhanced diamonds, sent JCK a handful of the heat-treated material, noting that their price tags are almost 20% of a natural black diamond's cost, and about 50% of the price of an irradiated black diamond. "It's not that these diamonds are not worth the money," says Rahul Karnavat. "It's that most people would not know that they are buying a heated piece of bort. They think

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