what is carat

What are carats?

When we wonder what jewelry to buy we often focus on shape, color and material. However, after a while we start noticing more detailed criteria. And here mysterious carats appear. What are they and how it can help us to evaluate the given product?

Carat is a unit of mass indicating weight of precious stones and pearls. International symbol of this unit is 1 CT. The word ‘carat’ comes from a french word “caraton” meaning locust bean, carob tree fruit. Carob seeds were used for centuries in the Middle East to define weight of precious stones. Since seeds weighted around 0.2 grams it has been adopted that 1 CT = 0.2 g. Properly cut brilliant diamond weighting 1 CT has a diameter of around 6.3mm.

Interestingly, the unit is also used to indicate purity of gold. However, in this case, symbol is 1K, it does not mean the weight but proportion of gold to other metals used in an alloy. It is accepted that pure gold has 24K – meaning all 24 parts of alloy are gold. For instance, in gold 14K the precious metal is 14/24 part of an alloy.
In Europe the fineness converted to percent is being used. Gold of 14k contains 58.5% of precious metal so the alloy mark is 585. Below I have attached a practical tally of all commonly used alloys.

24K – fineness 999 – 99.9% Au
22K – fineness 960 – 96.0% Au
18K – fineness 750 – 75.0% Au
14K – fineness 585 – 58.5% Au
12K – fineness 500 – 50.0% Au
10K – fineness 417 – 41.7% Au
9K – fineness 375 – 37.5% Au
8K – fineness 333 – 33.3% Au

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