Alexandrite

Alexandrite is the highly regarded color changing variety of Chrysoberyl. The color of Alexandrite changes under different lighting conditions. If viewed in daylight, its color is greenish blue to dark yellow-green. If viewed in incandescent or candle light, its color is pink to red. Alexandrite is a very rare and highly valuable gemstone, and until recently was extremely difficult to obtain due to its rarity. However, new sources in Brazil and Tanzania have made this gemstone available and more mainstream on the gemstone market.
Chemical Formula BeAl2O4
Color Blue, Red, Green, Yellow, Pink, Purple, Gray, Multicolored
Hardness 8.5
Crystal System Orthorhombic
Refractive Index 1.744Â -Â 1.755
SG 3.5Â -Â 3.8
Transparency Transparent to nearly opaque
Double Refraction .009
Luster Vitreous
Cleavage 1,1 ; 3,2. Often exhibits parting along twinned crystals.
Mineral Class Chrysoberyl