Alexandrite
Alexandrite is the color-change variety of chrysoberyl — one of the rarest and most valuable gemstones in the world. It appears green or teal in daylight and transforms to red or purple in incandescent light due to selective absorption of light wavelengths. The effect is caused by chromium. Fine alexandrite is worth more per carat than diamond. Georgia has a historic US locality that has produced some of the finest domestic specimens.
Physical Properties
Chemical Formula
BeAl₂O₄ (color-change variety of chrysoberyl)
Hardness (Mohs)
8.5
Color
Green in daylight / red to purple in incandescent light
Luster
Vitreous to subadamantine
Crystal System
Orthorhombic
Streak
White
Cleavage
Distinct in one direction
Specific Gravity
3.68–3.78
🔍 Field Identification Tips
The color change from green (daylight) to red (incandescent light) is unmistakable and definitive. Hardness 8.5 (extremely hard — nearly as hard as sapphire). No cleavage (extremely tough). Distinguished from color-change garnet by crystal form and slightly different color change (garnet shifts blue-green to red-purple; alexandrite shifts green to raspberry red).
Varieties & Forms
📍 Where to Find Alexandrite in the US
Uses & Applications
Fine jewelry (June birthstone alongside pearl and moonstone), most prized of all color-change gems.
💰 Collector Value Guide
Chrysoberyl (yellow, no color change): $50–$500/ct. Weak color-change alexandrite: $500–$5,000/ct. Fine Russian alexandrite: $10,000–$50,000+/ct.
Find Alexandrite With Our Tools
Use the We Lick Rocks app to identify specimens, find dig sites, and connect with local rockhounds.