Chrysoberyl is a beryllium aluminum oxide with a hardness of 8.5. It is one of the hardest gemstone, second only to diamond and corundum. These gems are among the world’s rarest varieties.
Colorless chrysoberyls are extremely rare. Chatoyant cat’s eye occurs primarily with the single color varieties of yellow and green, but alexandrite also rarely occurs as chatoyant cat’s eye.
The name derives from the Greek word chrysos, which refers to the stone’s golden color. Chrysoberyl was treasured in Rome over two thousand years ago, and even earlier in China.
Deposits of the actual chrysoberyl are in Brazil and Sri Lanka, as well as Myanmar, Madagascar, Russia, Zimbabwe and the United States.
Chrysoberyl characteristically forms star-shaped crystals called sixlings. Its natural color may be grey, yellow, yellow-green, olive green or dark green.
Stones are fashioned mainly in step, Ceylon, and brilliant cuts. The famous Hope chrysoberyl (London), a light green, faceted stone of 45 ct, is completely clean.