9.0 on the Mohs scale.

Myanmar (Burma), Thailand, India, Sri Lanka (Ceylon), Tanzania, Afghanistan, Australia, Brazil, Cambodia, Malagasy Republic, Malawi, Pakistan, Zimbabwe (Rhodesia), United States (Montana, North Carolina).

Blue sapphires are found in the form of star sapphires. These six-rayed blue stars are very attractive and are much more valuable than the black variety. Care should be taken when identifying all forms of star corundum, as synthetic stars are very inexpensive to produce and are common. Synthetic stars appear to be of high quality, with very little if any irregularites, razor sharp stars. The natural stone tends to be irregular and imperfect, and the stars may be wavy, whereas the sythetic stars have very straight lined stars. An "L" stamped on the reverse of the stone identifies it as a synthetic "Linde star". The sapphires found on this page are all natural.

Blue star sapphire is always heat treated to produce, intensify or lighten color and/or improve color uniformity and appearance. Occasionally diffusion is used to produce asterism.

More information on gemstone enhancements.

Blue Star Sapphire is a member of the Sapphire gemstone family.