Sapphire
Chemical Formula	Al2O3
Species	Oxides & Hydroxides
Crystal System	Trigonal
Mohs Scale	9
Specific Gravity	3.95-4.03
Color	Every color except a shade of red – which is called a ruby – or pinkish-orange (the padparadscha)
Streak	white
Luster	vitreous
Refractive Index	nω=1.768–1.772nε=1.760–1.763,Birefringence 0.008
Cleavage	none
Fracture	conchoidal, splintery
Crystal Habit：massive and granular