Carat (purity)
The carat is a unit of measurement for gold alloys. In that context, one carat gold means that one twenty-fourth part of the alloy is gold, and the rest is made of other metal, generally silver or copper. Pure gold is soft, which makes it unusable for many purposes. Alloyed gold is harder than pure gold and so more suitable for applications such as jewellery. A 24 carat alloy actually contains 99.9 percent gold due to the difficulty of achieving 100% purity, 18 carat gold contains 75 percent gold, and so on. Sometimes, a scale of up to 1000 is used; as an example, gold 585 mean there is 58.5 percent gold in the alloy. This means that "Gold 585" is 14 carat.
