Understanding Gold Carats: 18K, 21K, 22K and 24K Explained
20 January 2025
What does carat mean in gold?
The carat (or karat, written as K) measures the purity of gold. Pure gold is 24 carats (24K). Other carats indicate how much of the metal is pure gold versus alloy metals like silver or copper.
The formula is simple: divide the carat number by 24.
| Carat | Purity | Gold Content | |-------|--------|-------------| | 24K | 99.9% | Nearly pure gold | | 22K | 91.67% | Most common for South Asian jewellery | | 21K | 87.5% | Popular in Gulf jewellery markets | | 18K | 75% | Common in Western fine jewellery | | 9K | 37.5% | Most common in UK high street jewellery |
How to find the carat of your gold
Gold jewellery is stamped (hallmarked) with a number that indicates its purity:
- 999 = 24K (99.9% pure)
- 916 = 22K (91.6% pure)
- 875 = 21K (87.5% pure)
- 750 = 18K (75% pure)
- 585 = 14K (58.5% pure)
- 375 = 9K (37.5% pure)
Look for these stamps on clasps, inside rings, or on the back of pendants.
Which carat is best for jewellery?
22K gold is the most popular choice for South Asian jewellery — it's high purity while still being durable enough for everyday wear. 24K gold is too soft for most jewellery and is mainly used for gold bars, coins, and some Indian temple jewellery.
18K gold is commonly used in Western fine jewellery and is more scratch-resistant than 22K, making it suitable for rings that take heavy wear.
How carat affects price
The higher the carat, the more gold content, and the higher the price per gram. This is why our buying calculator asks you to specify the carat before calculating — a 24K necklace is significantly more valuable than an 18K necklace of the same weight.
When selling gold, always make sure the buyer knows the exact carat. Some unscrupulous buyers might try to undervalue 22K pieces as 18K — reducing their offer by nearly 20%.