gemstone

Red corundum (ruby-colored polished crystal)

Corundum, aluminum oxide (Al₂O₃); red color is typically caused by chromium

AI-generated identification · may be incorrect

Mohs hardness 9, vitreous luster, deep red color, trigonal crystal structure, and no true cleavage. The pointed, polished form and uniform translucency suggest a cut or synthetic specimen; visual identification cannot confirm natural origin.

Identified August 20, 2026More gemstone →

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At a glance

Common name: Red corundum (ruby-colored polished crystal)
Scientific name: Corundum, aluminum oxide (Al₂O₃); red color is typically caused by chromium
Category: gemstone
Identified: August 20, 2026
Method: Standard

AI Estimated Value

About $5–$30 if synthetic or glass-like; $50–$500+ for a verified natural ruby specimen, with fine transparent gems potentially worth far more.

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

Corundum forms in aluminum-rich metamorphic rocks and some igneous deposits; ruby-bearing rocks commonly formed during Precambrian to younger metamorphic events. Synthetic ruby is produced industrially by flame-fusion or hydrothermal methods.

Uses & applications

Used as an abrasive and in scratch-resistant components; gem-quality natural ruby is used in jewelry, while synthetic ruby is common for ornaments, lasers, and watch bearings.

Geological facts

Ruby is the red variety of corundum; other colors are called sapphire. The specimen’s intense uniform color and unusually smooth elongated shape may indicate synthetic ruby or dyed glass rather than natural ruby.

Field identification & locations

Test hardness, refractive index, inclusions, and chemistry; a gem laboratory is needed to distinguish natural ruby from synthetic material or glass. Natural ruby occurs notably in Myanmar, Mozambique, Sri Lanka, and Tanzania.