What is a Carat
According to the oxford dictionary meaning of carat is “a unit of mass and is used for measuring gemstones and pearls. It is a unit of mass equal to 200 grams i.e 0.2 mg. It is also used as a measure of the purity of gold , 24-carat being pure gold”. There is the difference between the gold purity carat and the gem stone carat. The gem stone carat refers to the weight of the gem stone while the gold carat refers to the purity of gold. Pure gold is soft rendering it unfit for making jewellery hence some impurities are like copper, zinc or silver are added to gold. 24 carat gold means pure gold while 22 carat gold means the quantity of gold is 92.6% with remaining 7.4% is other metals. The concept of purity of gold in terms of carats comes from the grains of gold in the solidus of coin where in one solidus= 24 carats. Its an ancient system used by the Greeks and Romans that has survived the test of time.
The system of marking the gold with its purity has become prevalent with awareness of the buyers. A 22/22 marking means that the skin of the jewellery is 22 carats and after melting the gold the minimum purity achieved will be 22 carats. This marking has thus gained popularity and reduced the scope of cheating while purchasing gold.
In terms of weight of gemstone the present 200mg standard carat was adopted in the General conference on weights and measures in 1907. Before that there were various standards of carat across the globe. The word comes from carob seed which was used all across the world as the standard measure for weighing precious gems.
Its first reference can be found in the 15th century. Till 1888 the carat in bratain was around 3.17 grains. In Egypt the carat before standardization was 196 mg approximately while the Arabic carat was in the vicinity of 212 mg.
According to another popular dictionary, there are two types of carats— the pound carat and the ounce carat.
Gem stones value is determined by its weight in carats, rate per carat of a two carat stone would be much more than what a one carat diamond would cost. Its difficult to find good gems with quality in higher carat weight hence the value multiplies.
It is important to be aware that while the term carat refers only to weight of the gem stone like diamonds, opals, emeralds, rubies and sapphires etc. It has nothing to do with the dimensions or the shape of the gem stone.