The name chrysoberyl is derived from two Greek words signifying golden-beryl. This name is well suited to the golden-yellow variety, but the chrysoberyl also includes many other colors: such as green, greenish-yellow, brownish-yellow, white, and dark-brown to black. Three varieties of chrysoberyls are known as cat’s-eyes, cymophanes, and alexandrites. The composition of the chrysoberyl is: alumina, 80.2; glucina, 19.8; with traces of protoxide of iron and oxides of lead and copper. The chrysoberyl is doubly refractive to a high degree, acquires positive electricity lasting several hours, is infusible alone, but melts with borax or salts of phosphorus to a clear glass, though with difficulty. The chrysoberyl is unaffected by acids, but with a solution of cobalt nitrate the powdered mineral becomes blue. Transparent greenish-yellow chrysoberyls are sometimes called Oriental chrysolites. These, and the brownish-yellow stones are the gems most used in jewelry. The chrysoberyl cat’s-eye, or Ceylon cat’s-eye, is found in various The cat’s-eye chrysoberyls are always cut convex or cabochon shape, and as the stone is moved from side to side the band of light moves over its surface. |