Sapphire (Greek: σάπφειρος; sappheiros, "blue stone") is a gemstone variety of the mineral corundum, an aluminium oxide (α-Al2O3), when it is a color other than red or dark pink, in which case the gem would instead be called a ruby, considered to be a different gemstone. Trace amounts of other elements such as iron, titanium, or chromium can give corundum blue, yellow, pink, purple, orange, or greenish color. Pink-orange sapphires are also called padparadscha. Pure chromium is the distinct impurity of rubies. However, a combination of e.g. chromium and titanium can give a sapphire of a color distinct from red.
The sapphire is one of the two or three gem-varieties of corundum, with another one being the red or deep pink ruby. Although blue is their most well-known color, sapphires are made up of any color of corundum except for red (red ones are called rubies). Sapphires may also be colorless, and they are also found in shades of gray and black.
Padparadscha is a pink-orange corundum, with a low to medium saturation and light tone, originally being mined in Sri Lanka, but also found in deposits in Vietnam and Africa; Padparadscha sapphires are very rare and highly valued. The name derives from the Sinhalese word for lotus blossom. Along with rubies, they are the only type of corundum to be given their own name instead of being called a particular colored sapphire. Padparadscha used to be a subvariety of ruby. The rarest of all padparadschas is the totally natural variety, with no sign of treatment.
