Buy gems by weight. Shop from our extensive range of beautiful, natural 18-carat gems. Browse the largest selection of natural loose colored gemstones available in 18 carats. Our large gemstone selection includes many popular gem types, such as amethyst, citrine, topaz and turquoise, and lesser-known gems, including ammolite, cat's eye aquamarine and maw-sit-sit. Large, natural 18-carat gems are perfect for making statement jewelry, such as oversized pendants and rings. From here, you can use our filters at the top or on the left-hand side to find gems by gem type, color, shape, cut and so on. For example, select 'moonstone' to see all of our 18-carat moonstone gems. Select 'pink' to shop for 18-carat pink gems. You can also filter by single, pairs, lots, faceted gems or cabochons by using the check boxes at the top.