Carats and Karats of Gold

Carats and Karats of Gold

In the jewellery trade ‘Carat’ is the word we use to describe golds purity. The weight of gold is traditionally measured troy ounces, however, its purity is measured in ‘carats’. In the UK and most of the English-speaking Commonwealth carat is spelt with a ‘C’, although in modern, American-English the same word is spelt with a ‘K’ and is often abbreviated to the symbol ‘K’.

Confusingly, carat is also the name of a unit of measurement used to weigh diamonds and other gemstones. Although, these weighing carats are always spelt with a ‘C’ rather than a ‘K’ and are usually abbreviated to the symbol ‘ct’.


When we are talking about carat gold, we simply mean parts-per-24. So, pure gold is 24 carat. This is a very old measuring system, the same as hours in the day, which it is said can be traced back at least 4000 years, to ancient Babylon.

The word carat is assumed to be a medieval French translation of an Arabic term, which ultimately originates from the Greek kerátion (κεράτιον) meaning carob seed. In antiquity, grains of wheat or barley and carob tree seeds were used by Mediterranean traders to define units of mass. According to custom, one carob seed was equivalent to the weight of four wheat grains or three barleycorns. Interestingly, ‘grains’ are another measurement that is still used in the jewellery trade. This time for weighing pearls.

When making jewellery the gold we use is usually an alloy. The process of alloying, or mixing other metals with pure gold, makes the malleable pure gold less likely to bend out of shape, but can also be used to change its colour or durability, and reduce its cost. The less pure gold that is used in the gold alloy, the lower the gold’s carat.

Different parts of the world have distinct preferences for the carat of gold used in their jewellery. Many countries have a legal standard for the minimum carat permitted to be called gold.

In China, 24 carat Chuk Kam (literally ‘full gold’) still comprises the majority of gold sales. The rest of Asia and the Middle East seem to prefer their jewellery to be between 20 and 22 carat. While an 18 carat gold alloy best suites the style of jewellery worn in the Western World. With 14 or 9 carat used as a tough, cost effective gold for everyday wear.

Fineness is another way of expressing the precious metal content of gold jewellery, and represents the purity in parts per thousand. This system is used in various Hallmarking systems around the world, often in the form of a Common Control Mark. When stamped on jewellery this is typically stated as a decimal, without the preceding 0 or the decimal point.

The most common Fineness marks you will find stamped onto gold jewellery are:

.333 = 8 carat (legal minimum standard for Denmark and Greece)

.375 = 9 carat (legal minimum standard for the UK, Most of Western Europe, Canada & Australia)

.417 = 10 carat (legal minimum standard for the USA)

.583 or .585 = 14 carat

.750 = 18 carat

.833 = 20 carat

.916 = 22 carat

.999 (1000) = 24 carat pure gold

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