Sapphire

saf'ir, a beautiful, transparent, precious stone. It is a form of corundum. It is akin to the red ruby, but differs from it in being of a blue color. A yellow sapphire is known as a topaz; a green, as an emerald; a violet as an amethyst. The finest sapphires are perhaps those of Ceylon, Cashmere, and Siam. Beautiful sapphires are obtained from Queensland, Australia. Sapphires of a rich, delicate blue color are found in the gold-bearing gravels of Montana. The sapphire owes its beauty to a quality akin to phosphorescence. See Corundum; Ruby

Now glowed the firmament with living sapphires. Milton, Paradise Lost.