Phenomenon · Reviewed definition

Chatoyancy

A bright, mobile band of reflected or scattered light, often produced by aligned internal features and displayed by a cabochon.[1]

Also known as: Cat’s-Eye Effect

Plain English

What it means

Chatoyancy is the cat’s-eye band that moves across certain gems.

Why it matters

The effect reveals the optical influence of aligned structures or inclusions.

What it does not tell you

The sharpness and visibility depend on material, inclusions, cut, and lighting.

Evidence

References

  1. 1
    Structures Behind the Spectacle: Optical Effects in Phenomenal Gemstones

    Gemological Institute of America

    Open source