|1.||having changeable lustre; twinkling|
|2.||(of a gem, esp a cabochon) displaying a band of light reflected off inclusions of other minerals|
|3.||a gemstone with a changeable lustre, such as a cat's eye|
|[C18: from French, from chatoyer to gleam like a cat's eyes, from chat|
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, imperfections, or inclusions are oriented along a crystallographic axis; it is this same kind of orientation, but along three axes, that accounts for the asterism of star sapphire and ruby.
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