gemstone

Blue cabochon gemstone, likely blue sapphire

Corundum (Al₂O₃), colored blue by trace iron and titanium

AI-generated identification · may be incorrect

Oval, polished cabochon with deep blue color and vitreous luster; sapphire has Mohs hardness 9 and a trigonal crystal structure. The photo alone cannot confirm whether this is natural sapphire or a simulant/treated stone.

Identified October 11, 2026More gemstone →

Explore Blue cabochon gemstone, likely blue sapphire in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Natural sapphire forms in aluminum-rich, silica-poor rocks and is concentrated in alluvial deposits; deposits range from ancient to geologically recent. Heat treatment is common in commercial gems.

Uses & applications

Used in jewelry and valued as a durable gemstone; synthetic corundum also has industrial uses.

Geological facts

Sapphire is a variety of corundum; blue color commonly results from iron–titanium impurities.

Field identification & locations

Sapphire occurs in places including Sri Lanka, Madagascar, Myanmar, and Australia. Confirm identity and natural origin with gemological testing; the cabochon cut and dark blue appearance are not diagnostic.