;Natural Alexandrite;Grown Alexandrite
Chemical formula;BeAl2O4:Cr3+;BeAl2O4:Cr3+
Density, g / cm3;3,63-3,75;3,69-3,75
Mohs Hardness;8,5;8,5
Syngony;Rhombic;Rhombic
Options of el.cells;a=4.425, b=9.402, c=5.474;a=4.248, b=9.41, c=5.481
Refractive index;1,740-1,747;1,745-1,754
Birefringence;0,01;0,01
Pleochroism;Strong;Strong
Color at daylight;Greenish Blue;Greenish Blue
Color at incandescent bulbs;Violet-purple;Violet-purple