Rock Identifier
Blue Opal Inlay (Simulated/Lab-created) (Hydrated Amorphous Silica (SiO2·nH2O) with polymer resin) — mineraloid
mineraloid

Blue Opal Inlay (Simulated/Lab-created)

Hydrated Amorphous Silica (SiO2·nH2O) with polymer resin

Hardness: 5.5-6.5 (Lab-created) or 4 (Natural). Color: Electric blue with bright play-of-color. Luster: Vitreous to resinous. Structure: Amorphous (non-crystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 1.9-2.2.

Hardness
5
Color
Electric blue with bright play-of-color
Luster
Vitreous to resinous
Identified More mineraloid

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Physical properties

Hardness: 5.5-6.5 (Lab-created) or 4 (Natural). Color: Electric blue with bright play-of-color. Luster: Vitreous to resinous. Structure: Amorphous (non-crystalline). Cleavage: None (conchoidal fracture). Specific Gravity: 1.9-2.2.

Formation & geological history

Laboratory-grown via the Gilson process (precipitation of silica spheres) or imitation resin. Natural opal forms in sedimentary environments from silica-rich groundwater over millions of years. This jewelry specimen is likely lab-created for durability and color consistency.

Uses & applications

Primarily used in fashion jewelry and accessories. Synthetic or 'lab' opal is preferred for inlays like this because it is more durable and less prone to cracking (crazing) than natural precious opal.

Geological facts

Lab-created opals can take up to a year to 'grow' in a laboratory. They are chemically identical to natural opals but often contain a resin binder to make them more stable for jewelry. The starfish motif is a common design for souvenir jewelry found in coastal regions.

Field identification & locations

Identify in the field by looking for a 'chicken wire' or columnar pattern of color flashes, which is a hallmark of lab-grown opal. Natural opal flashes are more irregular. Often found in silver-plated or sterling silver settings in gift shops.