Although they have a common origin and are pronounced the same, carat and karat now have different meanings.
A Carat: is a measure of the weight of a gemstone and diamonds.
The carat, the standard unit of weight for diamonds and other gemstones, takes its name from the carob seed. Because these small seeds had a fairly uniform weight, early gem traders used them as counterweights in their balance scales. The modern metric carat, equal to 0.2 grams, was adopted by the United States in 1913 and other countries soon after. Today, a carat weighs the same in every corner of the world.
"One carat is equal to 0.2 grams"
A Karat is a measure of gold purity.
“Karat” is especially used in measuring the purity of gold.
The purity of gold can be scaled from 1 to 24.
below are carats correspond to the % of gold included in the alloy :
24K = 99.5 %
22K = 92%
18K = 75%
14K = 58.8%
9K = 37.5%
24 karat is the purest form of gold, but pure gold (24 carats) is rarely used in jewellery as it is too soft. almost in the watch & jewellery industry companies works with a gold alloy comprising 18K of pure gold per 24K. Gold is alloyed with other metals to give it the required firmness, mechanical strength and colouring, but in countries like India, 22 karat jewellery is more favoured and popular, and gold with less than 10 karats is not considered gold.
The karat level is stamped on each piece of jewellery, a karat is written as "K" but almost of a watches on the case back, a gold purity written as "Au750" is mean gold 750 mg of pure gold per 1000 mg.
Synopsis :
A Carat: is a measure of the weight of a gemstone and diamonds.