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What is carat?

March 29, 2017/ BY Frank van Poorten

What is carat you ask? Carat is the unit of mass in precious (gem)stones and diamonds. The word originates from the Greek word ‘Keratia’ which is the name of the seed of the fruit of the carob tree. It ended up from the Arabic ‘Qirat‘ Italian ‘Carato‘ and the French ‘Carat’ to the English language as ‘Carat’.

The weight of a carat for diamonds

Initially, almost all countries had their own weight of carat, they all hovered around 200 milligrams. The seeds of a carob tree were almost always 200 milligram. These seeds were uses as counterweight at a gem stone and diamond scale because of their constant weight and mass.

One carat is 200 milligrams

Since 1907, the metric carat is fixed at 200 mg. Carats are also expressed in points. One carat of 200 milligrams equals 100 points. Half a carat weighs therefore 100 milligrams and is 50 points. Moreover, a carat is always expressed in two decimals. For example 56 points is 0.56 carat.

sizes diamonds from 50 points to 200

Is weight the same as carat?

The specific weight of diamond varies from 3.47 to 3.55 gram per cm³. This has nothing to do with the weight in carats. This specific weight or density is used to check whether a diamond is real or fake.

Why use carat to weigh diamonds and gemstones?

Gemstones and diamonds are rare stones that are usually prepared and processed in jewelry and decorative objects. These precious stones are known for their beauty, sustainability and rarity. These three factors make diamonds and gemstones very precious and expensive. Because of the high prices, the metric system for carats was introduced. With this system, you are sure that in every place the same weights are used to weigh a diamond or a gemstone.  

weighin diamonds and gemstones

The difference between carat and karat?

Many people struggle in finding the difference between carat and karat; they often think they’re the same. However, the carats of gemstones and diamonds are not the same as karats in noble metals such as gold and silver.

Not carat, but karat for gold and silver

The karat of noble metals refers to the composition of the metal. There are for example 14 karat gold rings and 18 karat gold rings. The higher the number, the higher the percentage of gold in the metal. A 14 karat gold ring has a percentage of 58.5% gold. At a golden ring of 18 karat, the metal exists for 75% of gold.

scale for gold

The 4 C’s of diamond valuation

Carat is the first C of 4 C’s for diamond evaluation. Read how the carat determines the price of a diamond or learn more about the 4 C’s in a free guided tour through our diamond factory in Amsterdam.

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