To start, it is important to understand what a “karat” of gold actually is. “Karats”, often abbreviated as “kt”, are the units of measurement, which are used to describe the purity of gold. As you may already know, 24 karat gold is the measurement for pure gold. This can also be understood as 24 karats = 1000 parts gold, which = 100% pure gold.
Pure gold is extremely malleable and is very soft. For this reason, gold is mixed with other metals such as copper to give it strength and durability. Other alloys, such as palladium, can also be mixed in to change the color of the gold to white. A precise calculation of combining different alloys in the mixture can even produce rose gold, blue gold, green gold and other colors.
24kt = 100% Pure Gold (1000 parts)
18kt = 75% Pure Gold + 25% Alloy
750 parts gold mixed with 250 parts Alloy
14kt = 58.3% Pure Gold + 41.7% Alloy
583 parts gold mixed with 417 parts Alloy
(14kt gold could be rounded up and marked as 585, as opposed to 583.)
10kt = 41.7% Pure Gold + 58.3% Alloy
417 parts gold mixed with 583 parts Alloy
18kt, 14kt and 10kt are most commonly used to make jewellery in North America.
The amount of pure gold in the overall mixture is what is measured as the pure gold content and determines what “karat” the item is. For example, if a ring is made with 75% pure gold and balance of 25% is a mixture of copper and palladium, the result will be an 18kt White Gold ring.
With the gold price reaching well over $1,000 per troy ounce, it is easy to understand how the same piece of jewellery can vary in price depending on whether it is made in 10kt, 14kt or 18kt gold.
So the next time you are having your custom piece of jewellery designed, and the jeweller asks you what karat gold you would like to have your item made in, you will be able to confidently make your decision.