What does karat mean for gold jewellery?
By Jared James · Last updated 21 May 2026
Definition
Karat, often spelled carat in Britain and Australia and shortened to ct or k, is a measure of the purity of gold, expressed as a fraction of 24 parts. Pure gold is 24k, meaning all 24 parts are gold with nothing added. 18k gold is 18 parts gold and 6 parts other metals, 75% pure, while 9k gold is 9 parts gold and 15 parts alloy, 37.5% pure. Australia uses 9ct as its minimum legal standard for gold jewellery, and the karat stamp on a piece tells you precisely how much gold it contains.
Frequently asked questions
- What is the difference between karat and carat?
- In the context of gold, they mean exactly the same thing: a measure of purity out of 24. The spelling karat is used in the United States while carat is used in Britain, Australia and many other English-speaking countries, but both refer to the same gold purity standard. Carat is also separately used to measure the weight of gemstones, which is a completely different meaning, and this is where the two uses of the word can cause confusion.
- Which karat gold is best for jewellery?
- It depends on what you need. 24k is pure gold but too soft for most jewellery. 18ct offers the deepest, warmest gold colour and is very good for sensitive skin, while 14k or 9ct gold is harder, more scratch-resistant and more affordable. In Australia, 9ct and 18ct are the most common choices for fine jewellery, and both are excellent for everyday wear.
- How do I read the karat stamp on gold jewellery?
- A hallmark or stamp on gold jewellery tells you the purity. You will see numbers like 375 for 9ct, 585 for 14ct or 750 for 18ct, which are the decimal equivalents of the gold fraction. You might also see the letters ct or k followed by a number, as in 18ct or 18k, or just the number stamped on its own. These all mean the same thing.
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