Why Is Gold Measured in Carats?
The term carat comes from the name of the bean of the carob tree. In earlier times, carob beans were used to measure the weight of gold and precious stones, which were described as being so many “beans-weight” or “carats.”
Because of its softness, gold must be alloyed (mixed) with other metals, such as copper and platinum, to make jewelry.
Gold alloys are measured by carats. The purity of a gold alloy is expressed as the number of these parts of gold it contains. A carat is equal to one twenty-fourth part of the amount of gold in the alloy—twenty-four carat (24K) is pure gold; fourteen carat (14K) gold is 14 parts gold to 10 parts alloy.
Karat, also spelled Carat, is a measure of the purity of gold. It is spelled carat outside the United States but should not be confused with the unit used to measure the weight of gems, also called carat.