Reference work entry
In China’s gem industry, chrysoberyl is also known as ‘Golden Green Jade’ or ‘Golden Green Beryllium’. The name chrysoberyl is derived from the Greek word ‘chryso’, meaning a gold-white spar. It is actually an oxide of beryllium in the spinel family, and its main composition is beryllium aluminate (BeAl 2O 4). The Mohs hardness is 8.5. It usually contains inclusions of dense silk-like or tubular rutile, and its chatoyancy (cat’s eye effect) is superior to other gemstones. Therefore, the term ‘cat’s eye’, when referring to a gemstone, only applies to cat’s eye chrysoberyl. For other gems with a similar effect, the cat’s eye nomenclature must be combined with the name of the mineral, such as cat’s eye quartz or cat’s eye aquamarine. A variety of chrysoberyl called alexandrite changes colour from daylight to artificial light. They are high-quality rare and precious gems (Fig. 31).
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