cat’s-eye, any of several gemstones that, when cut en cabochon (in convex form, highly polished), display a luminous band reminiscent of the eye of a cat; this particular quality is termed chatoyancy. Precious cat’s-eye, the rarest and most highly prized, is a greenish chatoyant variety of chrysoberyl called cymophane; the chatoyant effect is due to minute parallel cavities. Quartz cat’s-eye, the commonest, owes its chatoyancy and grayish green or greenish colour to parallel fibres of asbestos in the quartz. The two may be distinguished by their specific gravities; chrysoberyl is much denser. Crocidolite cat’s-eye (African cat’s-eye), more commonly known as tigereye (or tiger’s-eye), is quartz that contains oriented fibres of crocidolite that have been replaced by silica. Corundum cat’s-eye is an imperfect star sapphire or ruby in which the star is reduced to a luminous zone.

The Editors of Encyclopaedia Britannica This article was most recently revised and updated by Michael Ray.
Britannica Chatbot logo

Britannica Chatbot

Chatbot answers are created from Britannica articles using AI. This is a beta feature. AI answers may contain errors. Please verify important information using Britannica articles. About Britannica AI.