Sapphire
Sapphire, like diamond, ruby and emerald, is counted among the precious stones. Like ruby, it is a crystallized form of the mineral corundum. It is the third hardest mineral in the world (after diamond and moissanite) with hardness 9 on the Mohs scale (Diamond is 10).
Sapphire is best known for its blue color, but there are also beautiful yellow, purple, orange and green sapphires.
The highest quality stones are found in Kashmir. In addition, sapphires from Myanmar (Burma), Sri Lanka (Ceylon), Thailand (Siam) and Madagascar are also of excellent quality.