Carat or Karat
A carat is a unit of weight that is equal to 200 milligrams or 100 points. Diamonds or gemstones weighing less than 1 carat are expressed as a fraction of a carat, 1/2 carat, or in points, 50 points. Carats is often abbreviated ct. or cts. Jewelry with multiple diamonds or gemstones are often given a single weight abbreviated as ctw. meaning carat total weight.
A karat is a unit of fineness or purity in gold. Pure gold, at least .999 percent pure gold, is 24 karat. Karat is most commonly abbreviated K. An 18K gold ring would contain 18 parts pure gold with the other 6 parts being alloy. A 14K gold ring would contain 14 parts pure gold and 10 parts other metals.
