Chrysoberyl

History
Known in ancient times, chrysoberyl is named from the Greek "chrysos" meaning gold, and "berylos" meaning pure crystal. The yellow and green varieties of chrysoberyl have been known in the gem world for hundreds of years, with the cat's eye chrysoberyl being the most desired.

Features
Chrysoberyl generally comes in green, greenish yellow or brown, and is frequently free of inclusions, however the cat's eye variety of chrysoberyl is one in which inclusions are not only desirable, but necessary, for it is these inclusions of parallel, microscopically small tubes or short fine needles that cause the cat's eye phenomenon.

Treatments
Chrysoberyl is generally untreated, however lab grown chrysoberyls which are produced usually imitate the alexandrite variety of chrysoberyl.

Principal Deposits
Sri Lanka produces some fine cat's eye chrysoberyls. Occurrences of other chrysoberyls include Brazil, Rhodesia, Madagascar and Myanmar.

Rarity
Green and yellowish green varieties of chrysoberyl, while not as common as some stones, are more common than cat's eye chrysoberyls. The rarest cat's eye chrysoberyls have a fine golden honey color, and give the impression of an eye opening and closing as a single point of light passes over it.