What is a "karat"?

A karat is a unit of measurement used to denote the purity of gold, with one karat being equal to 1/24th of the whole. Therefore, 24-karat gold is considered to be pure gold. The higher the karat number, the higher the percentage of gold in the item. For example, 18-karat gold contains 75% gold, while 14-karat gold contains 58.3% gold. Karat is also used as a term to describe the weight of gemstones, with one karat equal to 0.2 grams. The term "carat" is sometimes used interchangeably with "karat," but carat is generally used to describe the weight of diamonds and other gemstones, while karat is used to describe the purity of gold.