gemstone

Opal cabochon or opal-like decorative specimen

Hydrated amorphous silica, SiO₂·nH₂O; likely synthetic or assembled opal material

AI-generated identification · may be incorrect

Strong multicolored play-of-color, vitreous-to-resinous luster, and no visible crystal structure; Mohs hardness about 5.5–6.5 for natural opal. The thick orange border and intensely uniform flash suggest a resin-backed, coated, or synthetic opal rather than solid natural opal.

Identified September 11, 2026More gemstone →

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Physical properties

Formation & geological history

Natural opal forms when silica-rich groundwater deposits hydrated silica in cavities and fractures, commonly in volcanic or sedimentary environments, especially Australia, Ethiopia, and Mexico. This appears human-processed and may contain resin or plastic backing, so a geological age cannot be assigned confidently.

Uses & applications

Used in jewelry, carvings, ornaments, and collector pieces; synthetic or assembled varieties are inexpensive decorative materials.

Geological facts

Play-of-color results from diffraction of light by regularly arranged microscopic silica spheres. A foil-like backing, vivid broad flashes, and orange resin edges are common signs of assembled or synthetic opal.

Field identification & locations

Check with magnification for a seam or layered backing, and use specific gravity, UV response, and professional testing; avoid heat and solvents. Likely opal doublet/triplet or synthetic opal, not a natural solid specimen.