PHYSICAL PROPERTIES
Chemistry: Al2O3
Composition: Aluminum Oxide
Class: Oxides and Hydroxides
Group: Hematite
Crystal System: trigonal; bar 3 2/m
Fracture: conchoidal
Hardness: 9
Specific Gravity: 3.99 - 4.0
Refractive Index: 1.757 - 1.779
Luster: vitreous to adamantine
Streak: white
Color: Most any color some stones show zoning
Cleavage: is absent, although there is parting which occurs in three directions
Transparency: Crystals are transparent to translucent
Associated Minerals: calcite, feldspars, garnets, micas and zoisite

ENHANCEMENTS:
Heat treating is Common. Diffusion treatment is done occasionally. Diffusion places a thin blue coating on colorless sapphire. Irradiation is rarely used. Irradiation turns colorless gems yellow, orange or light blue.

Corundum - Ruby and Sapphire:
Ruby and sapphire are actually the same material called corundum. All colors of corundum other than the light to deep reds and purple-reds are classified as sapphire, so sapphire can be pink, yellow, green, orange, violet, or colorless in addition to the commonly known shades of blue. Red and purple-red corundum is classified as ruby.

Corundum is the second hardest natural material, second to diamond, and because of its durability. It makes an excellent gem for jewelry.

Fancy color sapphires are green, yellow, intense orange to orange-red, violet to purplish violet, pink, or colorless. With this verity of colors. Sapphire can be used as durable stones in family jewelry or can accesorise any wardrobe.

Sapphire, the traditional birthstone for September, was thought of as the royal gemstone. It was thought to protect kings from harm and envy. It was also believed to have medicinal properties.