gemstone

Blue sapphire

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

AI-generated identification · may be incorrect

Mohs hardness 9; typically vivid to pale blue, vitreous luster, trigonal crystal structure, and no distinct cleavage. This appears to be a faceted, likely heat-treated gemstone; exact identity requires gemological testing.

Identified September 17, 2026More gemstone →

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At a glance

Common name: Blue sapphire
Scientific name: Corundum, aluminum oxide (Al₂O₃), colored blue mainly by iron and titanium
Category: gemstone
Identified: September 17, 2026
Method: Standard

AI Estimated Value

Approximately $50-$500 for commercial stones, $500-$10,000+ for fine natural gems, and $10,000-$100,000+ per carat for exceptional untreated Kashmir-type material; synthetic or heavily treated stones may cost $10-$100.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Forms in aluminum-rich metamorphic rocks such as marble and schist, or in basalt-related deposits; most gem-quality material is Cenozoic to older. Common sources include Sri Lanka, Kashmir, Myanmar, Madagascar, and Australia.

Uses & applications

Used primarily in jewelry and as a durable ornamental gemstone; synthetic corundum is also used for abrasives, watches, bearings, and optical components.

Geological facts

Blue sapphire is the traditional September birthstone and a variety of corundum; red corundum is ruby. Large, vivid, untreated stones with strong color and excellent clarity can be exceptionally valuable.

Field identification & locations

Identify by exceptional hardness, high refractive brilliance, and possible inclusions such as rutile “silk”; verify with refractive index, specific gravity, spectroscopy, and heat-treatment analysis. Natural sapphire commonly occurs in alluvial gravels and metamorphic terrains.