All gem-quality corundum that is not red is called sapphire, yet this name is popularly associated with the colour blue. Variation colour, due to iron and titanium impurities, spans many shades, but the most valuable is a clear, deep blue. Some stones, called”colour- change sapphire”, exhibit different shades of blue in artificial and natural light.


Good quality sapphire is found in Burma, Sri Lanka, and India. The best Indian sapphire is cornflower blue, and found in Kashmir, either in pegmatites or as waterworn pebbles in alluvial deposits. Sapphire from Thailand, Australia, and Nigeria is dark blue, and may appear nearly black. Montana(USA) produces sapphire of an attractive metallic blue. Other localities include Cambodia, Brazil Kenya, Malawi, and Colombia REMARK Synthetic sapphire production began in the late 19th century. Commercial quantities became available in the early 20th century.

Composition Aluminium Oxide
Luster Vitreous
Refractive Index 1.76 to 1.77
Specific Gravity 4.00
Mohs Hardness 9
DR 0.008