Star Ruby

A ruby is a pink to blood-red colored gemstone, a variety of the mineral corundum (aluminium
oxide). Other varieties of gem-quality corundum
are called sapphires. Some rubies show a
three-point or six-point asterism or "star". These
rubies are cut into cabochons to display the effect
properly. Furthermore, rubies can show color
changes—though this occurs very rarely—as well
as chatoyancy or the "cat's eye" effect.