gemstone

Cabochon-cut ruby (corundum)

Corundum, Al₂O₃; red color is caused mainly by chromium

AI-generated identification · may be incorrect

Deep red, translucent cabochon with vitreous luster; Mohs hardness 9, trigonal crystal structure, and no true cleavage. The photo alone cannot confirm whether it is natural, treated, or synthetic.

Identified October 11, 2026More gemstone →

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Physical properties

Deep red, translucent cabochon with vitreous luster; Mohs hardness 9, trigonal crystal structure, and no true cleavage. The photo alone cannot confirm whether it is natural, treated, or synthetic.

Formation & geological history

Natural ruby forms when aluminum-rich rocks crystallize under suitable conditions, often during metamorphism; ruby deposits range from ancient to geologically recent. Synthetic ruby is also widely produced.

Uses & applications

Used in jewelry and, because of its hardness, in specialized industrial and optical applications.

Geological facts

Ruby and sapphire are both varieties of corundum; the red variety is called ruby. The visible inclusions and appearance are not enough to establish gem quality or authenticity.

Field identification & locations

Confirm identity and natural origin with gemological testing; common sources include Myanmar, Mozambique, Sri Lanka, and Thailand. This polished cabochon’s value depends heavily on treatment, origin, clarity, and weight.