Carats: Gemstones vs. Gold

In the jewelry world, one letter makes a big difference.

Carat (ct) - Weight

Carat (with a C) is a unit of mass for gemstones. One carat equals 0.2 grams. It's derived from the carob seed, which was used as a counterweight in ancient bazaars because of its uniform size.

Karat (K) - Purity

Karat (with a K) measures the purity of gold. 24K is 100% pure gold. 18K is 18 parts gold and 6 parts alloy (75% pure). It has nothing to do with weight.