CHEMISTRY Al2O3
CRYSTALLOGRAPHY Hexagonal
REFRACTIVE INDEX 1.757 - 1.779
HARDNESS 9
SPECIFIC GRAVITY 3.99 - 4.0
CLEAVAGE None
HEAT SENSITIVE No
WEARABILITY* Excellent
SPECIAL CARE INSTRUCTIONS None
ENHANCEMENTS Heat treated. Common. Diffusion treatment, (places a thin blue coating on colorless sapphire.) Occasional. Irridation, (turns colorless gems yellow, orange or light blue.) Rare.
*Wearability is graded as Excellent, Very Good, Good, Poor, and Forget It!
For more details see the article on "Hardness and Wearability."