Chatoyance

The property of some minerals to exhibit a wavy, luminous band with a silky lustre, reminiscent of the eye of a cat, in the centre of a cabochon-cut (polished, with a rounded, unfaceted convex surface) stone. The effect, caused by parallel fibres or by oriented imperfections or inclusions within the stone, is typical of cat's-eye, tigereye, satin spar, and bronzite. The fibres,