gemstone

Raw ruby (corundum)

Ruby variety of corundum, aluminum oxide (Al₂O₃), colored chiefly by chromium

AI-generated identification · may be incorrect

Typically deep red to purplish-red with a vitreous to greasy luster; Mohs hardness 9, trigonal crystal structure, and poor cleavage. The specimen appears massive and opaque-to-translucent, so visual identification is provisional.

Identified August 28, 2026More gemstone →

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At a glance

Common name: Raw ruby (corundum)
Scientific name: Ruby variety of corundum, aluminum oxide (Al₂O₃), colored chiefly by chromium
Category: gemstone
Identified: August 28, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a small opaque rough specimen; $50–$500+ if strongly colored, translucent, and confirmed natural, while fine gem-quality ruby can be vastly more valuable.

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

Ruby forms mainly in metamorphic rocks such as marble and gneiss, or in associated igneous/metasomatic environments; many deposits are Paleozoic to younger. Weathering commonly concentrates resistant crystals in alluvial gravels.

Uses & applications

Gem-quality ruby is cut for jewelry; opaque or fractured material is sold as mineral specimens or used in abrasives and synthetic corundum products.

Geological facts

Ruby and sapphire are the same mineral; color distinguishes ruby from other corundum. Fluorescence under long-wave UV can support chromium-rich ruby identification, but testing is needed.

Field identification & locations

Look for very high scratch resistance, red color, curved or hexagonal crystal forms, and possible chromium-red fluorescence; distinguish from garnet, spinel, and red glass with hardness, refractive-index, and laboratory tests. Common localities include Myanmar, Mozambique, Sri Lanka, Thailand, Tanzania, and Afghanistan.