Sapphires, like rubies belong to the corundum family, which means the stone is extremely hard (nearly as hard as diamonds).
Sapphires are supposed to signify loyalty.
Most sapphires are found in India, Pakistan and Afghanistan. The best sapphires come from Kashmir, and are rare and expensive, making this a valuable birthstone.
In modern times the blue sapphire came to be associated with the British royal family, thanks to the 12 carat sapphire in Princess Diana's engagement ring, which is now worn by Kate, Duchess of Cambridge.