A gemstone is a piece of mineral, organic material or rock that is cut and polished for use in jewelry. They are valued for their beauty, rarity, and durability. Some common types of gemstones include diamonds, rubies, sapphires, emeralds, amethysts, opals, garnets, topazes, peridots, turquoises, and pearls among others. Gemstones are often used in jewelry such as rings, necklaces, bracelets, earrings or brooches to adorn the body. They can also be displayed in a museum setting for their beauty and educational value.