Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide (α-Al2O3) with trace amounts of elements such as iron, titanium, chromium, copper, or magnesium. … Commonly, natural sapphires are cut and polished into gemstones and worn in jewelry. It is very rare to find blue sapphires with extremely high clarity, making them very valuable. Price goes up with rarity. The most highly prized sapphires come from Kashmir.