Alexandrite

Physical Properties

Hardness: 8.5 on Mohs scale; Color: Pleochroic (green in daylight, reddish-purple in incandescent light); Luster: Vitreous; Crystal Structure: Orthorhombic; Specific Gravity: 3.70–3.78

Formation & Geological History

Formed in granitic pegmatites and mica schists where beryllium-rich rocks contact chromium-bearing rocks. Most deposits date from the Precambrian to Cenozoic eras.

Uses & Applications

Primary use is high-end jewelry and as a prized collector's gemstone due to its rarity and color-changing properties.

Geological Facts

First discovered in Russia's Ural Mountains in the 1830s and named after Tsar Alexander II. It is exceptionally rare because beryllium and chromium are rarely found in the same geological environment.

Field Identification & Locations

Identify by its unique 'emerald by day, ruby by night' color change. Found in Russia, Brazil, Sri Lanka, and East Africa. Collectors should look for a distinct shift in hue under different lighting sources.

Identified on: 4/14/2026

Mode: Standard