gemstone

Ruby (rough corundum)

Corundum, aluminum oxide (Al₂O₃), chromium-bearing variety

AI-generated identification · may be incorrect

Pink-red, translucent to opaque rough fragments with vitreous luster and irregular to partly crystalline faces. Mohs hardness 9; trigonal crystal system; no true cleavage; specific gravity about 3.9–4.1. Color may also indicate pink sapphire rather than ruby.

Identified September 20, 2026More gemstone →

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Physical properties

Formation & geological history

Forms mainly in metamorphic rocks such as marble and mica schist, or in related igneous environments; crystals may be concentrated in alluvial gravels. The photographed pieces are consistent with rough corundum, but treatment and exact identity require testing.

Uses & applications

Gemstones when transparent and clean; opaque material is used for specimens or abrasive applications. Faceted ruby and sapphire can be highly valuable.

Geological facts

Red color is caused chiefly by chromium; pink material with insufficient chromium is scientifically classified as pink sapphire. These fragments are not visibly gem-grade from the photograph.

Field identification & locations

Test with a hardness check only against known materials, measure specific gravity, and use a refractometer or Raman/XRF for confirmation; avoid scratching the specimen. Corundum is plausible in Ethiopia, including eastern and southern Ethiopian gem-producing regions, though the exact locality is uncertain.