Karat
A measure of gold purity in parts out of 24, where 24K is pure gold and lower karats contain more alloy.
Karat, always spelled with a K when it refers to gold, tells you how much of an alloy is actually gold, measured in twenty fourths. Pure gold is 24 karat, so 22K means 22 parts gold to 2 parts other metals, and 18K means 18 parts gold to 6 parts alloy. The higher the karat the more gold and the deeper the colour, but also the softer the metal, which is why most jewellery is not made from pure gold at all. Do not confuse karat with carat, the weight unit for gemstones, since the two sound identical but measure completely different things.
How karat is calculated
The scale is a simple fraction out of 24. Divide the karat number by 24 to get the share of pure gold: 24 divided by 24 is 1, so 24K is 100 percent gold. 22 divided by 24 is 0.916, so 22K is 91.6 percent gold. 18 divided by 24 is 0.75, giving 75 percent, and 14 divided by 24 is 0.583, giving about 58.3 percent.
That decimal, called the purity fraction, is what actually drives price. Multiply a piece's weight by its purity fraction and by the current gold rate and you get its metal value. A 10 gram 22K chain therefore contains 9.16 grams of pure gold, and it is that pure gold content the market pays for, not the full 10 grams.
- 24K equals 24 out of 24 parts, 100 percent pure gold.
- 22K equals 91.6 percent, the fraction 0.916.
- 18K equals 75 percent, the fraction 0.75.
- 14K equals about 58.3 percent, the fraction 0.583.
Why lower karats exist
Pure gold is beautiful but soft. It bends, scratches and wears far too easily to hold a diamond firmly or survive daily knocks, so it is mixed with metals such as copper, silver, palladium and zinc to add strength. Each step down in karat trades a little gold content for a lot more durability. 18K holds stones securely for fine jewellery, while 14K stands up to heavy everyday wear.
The alloy also shapes colour. More copper gives a rosier tone, white metals such as palladium give white gold, and the classic warm yellow deepens as karat rises. So karat is doing two jobs at once: it fixes how much gold you are buying, and it constrains what colour and hardness the finished piece can have.
Karat versus carat
These are two different measurements that happen to sound the same. Karat, with a K, measures the purity of gold in parts of 24. Carat, with a C, measures the weight of a diamond or gemstone, where one carat is 200 milligrams. A ring can be described as an 18K gold band set with a 1 carat diamond, and both numbers are correct because they describe different things.
In practice the context makes it clear. If the number sits next to gold and runs from about 9 to 24, it is karat purity. If it sits next to a diamond or coloured stone and is often a decimal like 0.75 or 1.20, it is carat weight.
- Karat measures gold purity in parts out of 24.
- 24K is pure gold, 22K is 91.6 percent, 18K is 75 percent, 14K is about 58.3 percent.
- The purity fraction from karat drives a piece's metal value.
- Lower karats are harder and more durable because of added alloy.
- Karat is gold purity, carat is gemstone weight, they are not the same.
Karat, in short.
What does 24K mean?
24K is pure gold, 24 parts out of 24, about 99.9 percent fine. It has the deepest yellow colour but is soft, so it is used mainly for coins and bars rather than everyday jewellery.
Is higher karat always better?
Not for every use. Higher karat means more gold and richer colour but softer metal. For rings that hold stones or take daily wear, a lower karat such as 18K or 14K is often the better, more durable choice.
What is the difference between karat and carat?
Karat with a K measures the purity of gold in parts of 24. Carat with a C measures the weight of a diamond or gemstone, where one carat equals 200 milligrams.
How do I turn karat into a purity percentage?
Divide the karat number by 24. So 22K is 22 divided by 24, which is 0.916 or 91.6 percent, and 18K is 18 divided by 24, which is 0.75 or 75 percent.
Related terms
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