Sapphire is the modern September birthstone and the gem designated for the 5th, 23rd and 45th wedding anniversary; a star sapphire is typically given on the 65th wedding anniversary.

Sapphire is a variety of the mineral species corundum. Sapphires occur in all colors of the rainbow with the exception of red, which is ruby. The name corundum comes from the ancient Sanskrit "kuruvindam", while the name "Sapphire" comes from the Persian word "safir", meaning "beloved of Saturn", (or Greek sapphiros). It is noted in several texts that sapphire was the lapis lazuli of the ancient world, probably because the stones both have the same intense blue coloring.

Sapphire is mined in Australia, Sri Lanka and Thailand. Other producers are Burma, Kampuchea, Kenya and Tanzania. Sapphires are commonly heated to improve their color and reduce cloudiness that is caused by rutile inclusions. The rutile inclusions are responsible for the "star" or "cat's eye" in star sapphires.