gemstone

Blue cabochon gemstone, likely sapphire

Corundum (Al₂O₃), blue variety colored mainly by iron and titanium

AI-generated identification · may be incorrect

Vivid blue, polished oval cabochon with vitreous-to-waxy luster; corundum hardness is Mohs 9, with no cleavage and trigonal crystal structure. The surrounding bright metal setting and apparent uniformity suggest a jewelry stone, possibly synthetic or glass imitation.

Identified August 12, 2026More gemstone →

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Physical properties

Formation & geological history

Natural sapphire forms in aluminum-rich metamorphic rocks or basalt-related deposits, typically during ancient geological events; synthetic sapphire is laboratory-grown. The image alone cannot establish age or natural origin.

Uses & applications

Used in rings and other jewelry; sapphire is durable and highly valued, while synthetic or imitation stones are inexpensive.

Geological facts

Asterism may appear as a six-rayed star in some cabochons containing rutile inclusions. Blue color is commonly enhanced by heat treatment.

Field identification & locations

Confirm with refractive index, hardness, magnification, and inclusions; a gemological laboratory is needed to distinguish natural, synthetic, and imitation material. Common sources include Sri Lanka, Myanmar, Kashmir, Madagascar, and Australia.