gemstone

Polished ruby-in-zoisite cabochon (probable)

Corundum (ruby, Al₂O₃) in zoisite matrix (Ca₂Al₃Si₃O₁₂(OH)); possibly green fuchsite quartzite

AI-generated identification · may be incorrect

Small oval polished cabochon with dark green matrix and vivid purple-red patches. Likely hardness varies greatly: ruby ~9 Mohs, zoisite ~6–7; vitreous to waxy luster, opaque, with no visible crystal faces. Identification is provisional from the image.

Identified August 25, 2026More gemstone →

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Physical properties

Formation & geological history

Ruby-in-zoisite forms when corundum crystallizes with zoisite during metamorphism of aluminum-rich rocks, commonly in East African metamorphic terranes. Geological ages vary, often Precambrian; the reported Sabah-area location makes locally traded/imported material more likely than a confirmed local origin.

Uses & applications

Used for cabochon jewelry, carvings, and mineral collecting. This small polished piece is generally inexpensive unless the ruby is abundant, bright, and translucent.

Geological facts

The green–red/purple contrast is characteristic of ruby-in-zoisite, often marketed as anyolite. Some visually similar stones contain fuchsite or chromian mica instead of zoisite.

Field identification & locations

Look for a green granular matrix containing embedded red-to-purple ruby areas; ruby should resist scratching by quartz, while the matrix should not. Common commercial sources include Tanzania and Kenya. A gemological test or refractive-index examination is needed for confirmation.