gemstone

Opal ring

Opal (hydrated amorphous silica, SiO₂·nH₂O)

AI-generated identification · may be incorrect

The cabochon shows pale blue-green play-of-color with a polished, vitreous-to-waxy luster; opal has no crystal structure, Mohs hardness about 5.5–6.5, and specific gravity around 2.0. The image does not reveal whether it is precious opal, common opal, or a composite.

Identified September 26, 2026More gemstone →

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Physical properties

Formation & geological history

Opal forms as silica-rich water deposits hydrated silica in cracks and cavities, often in volcanic rocks or sedimentary settings; its geological age varies widely.

Uses & applications

Used for jewelry and collecting; the metal setting is not identifiable from the image.

Geological facts

Opal’s shifting colors result from light interacting with ordered microscopic silica spheres; not all opal displays this effect.

Field identification & locations

Identify opal by its hydrated-silica character and, in precious varieties, changing spectral flashes as the stone moves. Major sources include Australia, Ethiopia, and Mexico.