Ruby (Raw/Rough)

Physical Properties

Hardness: 9 on Mohs scale; Color: Pinkish-red to deep violet-red; Luster: Adamantine to vitreous; Crystal structure: Trigonal/Hexagonal; Cleavage: None (parting sometimes present); Specific gravity: 3.97–4.05

Formation & Geological History

Formed through contact metamorphism or in igneous rocks like basalt. Found in marble-hosted environments or gravel-rich alluvial deposits. Rubies range in age from hundreds of millions to billions of years old depending on the source deposit.

Uses & Applications

Primarily used in high-end jewelry and as a gemstone for collectors. Industrial grade corundum is used for abrasives, lasers, and watch bearings.

Geological Facts

The red color is caused specifically by the presence of chromium. Without chromium, the mineral is simply called sapphire. It is the second hardest natural substance on Earth after diamond.

Field Identification & Locations

Identify in the field by its extreme hardness (scratching anything but diamond), its dense weight, and its fluorescent glow under UV light. Commonly found in Myanmar, Sri Lanka, Thailand, and Mozambique.

Identified on: 4/14/2026

Mode: Standard