Opal

Hydrated silica, either with play-of-color or without it as common opal.

Colors & patterns

White, black, translucent, orange and other body colors; some show shifting rainbow flashes.

Typical origins

Australia, Ethiopia and Mexico are important sources; different regions yield different types.

Hardness

About 5–6.5

Choosing & setting this material

Ask whether it is solid, a doublet or a triplet, and whether it is hydrophane. Heat, sudden temperature changes and unsuitable cleaning can damage opal.

Care & cleaning

Wipe gently with a soft, slightly damp cloth and dry promptly. Avoid soaking, acids, solvents, steam and ultrasonic cleaning. Store separately to protect the surface.

Origins above describe typical sources of the material, not the origin of an illustrated or stocked stone. Hardness measures scratch resistance, not resistance to breaking. Confirm the identity and treatments of the actual piece.

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Further reading: Material reference · GIA: gem treatments