gemstone

Star ruby cabochon ring

Corundum, Al₂O₃ (ruby variety), displaying asterism

AI-generated identification · may be incorrect

The domed pinkish-red cabochon shows a six-rayed star caused by oriented rutile inclusions; corundum has Mohs hardness 9, vitreous luster, trigonal crystal structure, and no cleavage. The ring setting appears gold-colored metal, but its composition cannot be confirmed visually.

Identified September 15, 2026More gemstone →

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Physical properties

Formation & geological history

Ruby forms in aluminum-rich, silica-poor metamorphic rocks such as marbles and schists, or in related basaltic environments; asterism develops from microscopic rutile needles. Geological ages vary widely, commonly Precambrian to younger metamorphic deposits.

Uses & applications

Used in jewelry and valued as a durable colored gemstone; star rubies are typically cabochon-cut to preserve the optical effect. Quality depends strongly on color, sharpness of the star, transparency, treatment, and proven origin.

Geological facts

The star is visible because reflected light concentrates along three pairs of rutile directions. The stone may also be pink sapphire or synthetic star corundum; image-only identification cannot establish species, treatment, or natural origin.

Field identification & locations

Check for a centered, sharp star that moves across the surface under a single light, strong hardness, and possible curved growth lines; gemological testing, spectroscopy, and microscopy are needed for confirmation. Common sources include Myanmar, Sri Lanka, Vietnam, Thailand, and Tanzania.