Carat
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CARAT
A very ancient unit of weight, standardized at the beginning of the twentieth century, the carat is used to measure the weight of precious stones to two decimals. One carat equals 200 milligrams.
The carat (ct or kt) is also a measure of the purity of gold. One carat represents 1/24 purity by mass. Precisely, the carat rating of the material corresponds to 1/24 of the mass of pure gold or platinum in the material divided by the total mass of the material. For example, 18-carat gold is 75% gold, 12-carat gold is 50% gold...
