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What Does Gold Carat Mean?

What Does Gold Carat Mean?

The Gold carat (ct) is a unit used to measure the purity of gold. It indicates the amount of pure gold in a given item.

1 carat represents 1/24th of the whole. Pure gold is 24 carats, meaning that it is, at minimum, 99.9% pure gold with, at maximum, 0.1% other metals present. However, gold used for jewellery and other applications is rarely pure, and its purity is measured in carats to determine its value.

For example, 18ct gold is 75% pure gold and 25% other metals, while 14ct gold is 58.3% pure gold and 41.7% other metals.

Typically, the higher the carat of gold, the more valuable it is. However, it also tends to be softer and more susceptible to damage or wear. It is important to understand the 'carat' when buying or selling gold, as it affects its value and durability.

How is Gold Carat Calculated?

It is represented as a fraction of 24, where 24ct denotes 99.9%, or more, pure gold (24/24).

For example:

1) If a piece of gold has the '916' hallmark, we can calculate how many carats it is: (916/1000) x 24 = 22ct ; it is 22 parts pure gold and 2 parts other metals.

2) If a piece of jewellery is 37.5% pure gold, we can calculate how many carats it is: (37.5/100) x 24 = 9ct ; it is 9 parts pure gold and 15 parts other metals.

3) If we have 22ct gold, we can calculate the hallmark it will have: 22/24 = 0.916 = 91.6% pure gold; this would have the '916' hallmark, as you multiply the percentage by 10.

The History of the Carat or Karat

The "Carat" (United Kingdom) or "Karat" (United States), is not to be confused with the unit used to measure the weight of gems. The term originated from the German gold coin called a 'mark' which was common in the 19th century. It weighed 24 carats, the same measurement used to weigh gems. Since they could not be produced in pure gold due to the metal being too soft, other metals were added, such as copper, to harden the coin. This then resulted in the term carat representing the percentage of its carat weight made up of pure Gold.

How else is the Purity of Gold Measured?

The terms "carat" and "karat" are primarily used in the United Kingdom and United States, respectively. Many European countries and all four Assay offices in the UK employ the Millesimal Fineness System for hallmarking. This system expresses the purity of Gold, Silver, and Platinum alloys as 'parts per thousand of pure metal in the alloy by mass'.

For example:

An alloy containing 62.5% pure Gold is shown as "625" and is usually rounded to a three digit number, particularly when used as a hallmark.

Durability and Wear-resistance

While high-carat gold is valuable and beautiful, it might not be the most practical choice for certain types of jewellery. Pure gold, or 24ct gold, is very malleable and can scratch or bend easily. As the carat decreases, the gold becomes harder and more durable due to the alloying with other metals like copper, silver, or palladium. For this reason, 18-carat or 14-carat gold is often used for engagement rings or jewellery items that are frequently worn. Read more about Gold Alloys here.

Choosing the right Gold Carat

The choice of gold carat depends on your preferences and the intended use of the item. If you're looking for a luxurious, high-value piece or an investment in gold bullion, higher purities like 24 or 22 carats are an excellent choice. On the other hand, if you want a more durable and more affordable piece of jewellery that can withstand daily wear, 18 or 14ct gold is a more practical option.


The carat of gold is a critical factor that influences both its value and durability. Whether you're investing in bullion, purchasing an engagement ring, or buying everyday jewellery, understanding the impact of carats will help you make informed choices and ensure your gold items meet your needs and expectations.