Gemstones and pearls are sold in metric carats. This cellphone contains more than 400 platinum diamonds, totaling more than 20 carats. The diamond weighs 184.75 carats (36.90 g). Diamond potential is estimated at 40 million carats. The finished opal weighs approximately 3,749 carats, or 0.75 kg. The rough diamond as originally discovered weighed 40.23 carats (8.046 g). The American Golden Topaz, a more recent gem, weighed a massive 22,892.5 carats. Diamonds of 25 carats and more usually have their own names. It is named after the Cullinan diamond, the largest diamond ever found at 3100 carats. It weighs and is set with 596 stones totaling 911.84 carats. Alexandrite in sizes over three carats are very rare. One tari weighed about one gram and was carats of gold. Its key pad contains nearly 5 carats of ruby bearings. The coin is struck in pure gold, 999.9 fine (24 carats). The rough stone weighed 13.9 carats (2.78 g).