Two words that sound identical but measure completely different things.
Karat and carat are pronounced the same way and often used interchangeably by mistake — but they measure two completely different properties of jewelry.
Karat (spelled with a K) measures how much pure gold is in a piece, out of 24 parts. 24 karat is 99.9% pure gold; 14 karat is 14 parts gold and 10 parts other metal, or 58.3% pure. The higher the karat, the more gold and the higher the melt value for a given weight. See the full Gold Karat & Purity Guide for every common karat.
Carat (spelled with a C) is a unit of weight for gemstones like diamonds, equal to 200 milligrams. A “1 carat diamond” describes how much the stone weighs, not how pure or valuable it is on its own — a diamond’s price also depends on cut, color, and clarity.
Both words trace back to the same root — the carob seed, once used as a small, fairly consistent weight for trading gold and gems. Over time, English split the spelling: karat stuck to gold purity, carat stuck to gemstone weight. Outside the US, you may also see “carat” used for both meanings, which adds to the confusion.
Karat has a K, like Kold — well, gold. Karat is about the metal. Carat is about the stone. If a listing says “14 carat gold,” it almost always means 14 karat — a common typo, not a different standard.
In everyday use, yes — 'carat' is often just a common misspelling of 'karat' when describing gold purity. They refer to the same 58.3% purity standard.
Yes. A diamond ring might be described as, for example, '14k gold with a 0.5 carat diamond' — the karat describes the gold band's purity, the carat describes the diamond's weight.