Sapphire is any colour of the mineral corundum other than red, those are called ruby, (see above) corundum is composed of aluminium oxide. Sapphires tend to be translucent or transparent and have high amounts of refraction. The most desirable sapphires are generally those with an intense blue colour with plenty of sparkle and life. Various shades of blue result from titanium and iron substitutions in the aluminium oxide crystal lattice. Some sapphires show a 3-point or 6-point star or asterism. These sapphires are cut into cabochons to display this effect. They can be found in Brazil, Tanzania, Sri Lanka, Kashmir, Thailand, Madagascar and Australia.

Colour: Shades of blue, other colours- padparadscha(salmon pink), pink and purple, orange and yellow, green, and colorless and black. Each category has its own color range.

Hardness: 9