gemstone

Rough dark-blue gemstone, possibly sapphire

Corundum (Al₂O₃), if sapphire; identification is uncertain from the image

AI-generated identification · may be incorrect

Opaque-to-translucent deep blue with a vitreous luster and irregular, angular surfaces; corundum has Mohs hardness 9 and a trigonal crystal structure. The pictured piece may be a rough or fractured fragment; color alone cannot confirm sapphire.

Identified October 11, 2026More gemstone →

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At a glance

Common name: Rough dark-blue gemstone, possibly sapphire
Scientific name: Corundum (Al₂O₃), if sapphire; identification is uncertain from the image
Category: gemstone
Identified: October 11, 2026
Method: Standard

AI Estimated Value

Unverified rough piece: roughly $1–$50; confirmed gem-quality material may be worth substantially more, depending on weight, clarity, treatment, and origin.

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

Sapphire forms in aluminum-rich, silica-poor metamorphic rocks or in igneous rocks such as basalt; natural deposits span many geological ages. It may later collect in stream gravels as a durable placer mineral.

Uses & applications

Quality sapphire is cut for jewelry; lower-grade corundum is used as an abrasive. Rough specimens are also collected.

Geological facts

Blue sapphire’s color commonly comes from trace iron and titanium; corundum without red coloration is broadly called sapphire.

Field identification & locations

Check hardness and crystal habit, but avoid scratching a potentially valuable specimen; confirm identity with gemological testing. Sapphire occurs in places including Sri Lanka, Madagascar, Australia, and Montana.