A karat stamp is the starting point. Here is what the marks mean and how to confirm them.
Last reviewed: 13 November 2026
Most gold jewellery carries a small mark showing its purity. The mark may be a karat number, such as 22K, 21K or 18K, or a fineness number that gives parts per thousand. The common fineness marks are 999 for 24K, 916 for 22K, 875 for 21K, 750 for 18K, 585 for 14K and 375 for 9K. So a ring stamped 750 is 75% gold, which is 18K. In some countries you may see the stamp written as 22KT, 22 CT or "916". These all mean the same thing.
The stamp tells you what the maker or shop claims. Whether you can rely on it depends on who put it there, and that is where hallmarks come in.
A hallmark is an official mark applied after independent testing. In several countries gold items must be tested and marked by an approved assay or hallmarking centre before they can be sold. A full hallmark usually includes the purity, a symbol for the testing centre and sometimes the year or a unique code. India, for example, has a national hallmarking scheme with a unique identification code on each piece, and the United Kingdom has a long-established system of assay offices. Other countries have their own rules or none at all, so check what applies where you are buying. A hallmark from an approved centre is more reliable than a shop's own stamp, because someone with no interest in the sale has tested it.
Keep these. They help if you want to sell the piece later or if there is a dispute about its purity.
Several home tests are popular. They can be useful for spotting obvious fakes, but none of them proves purity.
The most accurate non-destructive method is an X-ray fluorescence (XRF) analyser, which many jewellers and hallmarking centres use to read the composition of the metal in seconds. The traditional, most precise method is fire assay, which melts a small sample and is used in laboratories and refineries. If you need certainty, for example for a high-value purchase or an old inherited piece, take it to a hallmarking centre or a reputable jeweller with XRF equipment.
Gold-plated items have a very thin layer of gold over another metal and have almost no gold value. Gold-filled items have a thicker layer, still much less than solid gold. Solid gold is gold throughout, at the karat stated. The wording on a label matters: "gold plated," "gold tone," "vermeil" and "gold filled" are not solid gold. If the label does not say the karat and the metal, ask.
When you check the weight, remember that stones, pearls and enamel are not gold. A good invoice separates the gold weight from the stones. Also remember that chains and clasps may use solder of a slightly different purity. Small differences like this are normal and are why some testing results vary a little. Larger differences are not.
When in doubt, buy from an established jeweller who is willing to certify the purity in writing, and keep your receipt. Our guide to buying gold safely adds more on choosing where to buy.
These home methods are not reliable. They may seem to show a reaction, but they do not tell you the karat. Use a jeweller's acid test, XRF analyser or a hallmarking centre for a real answer.
14K is 58.5% gold, and 18K is 75% gold. 18K has a richer colour and a higher gold value per gram, while 14K is harder and cheaper. Both are widely used in jewellery.
White gold is gold mixed with white metals such as palladium or nickel, often with a thin rhodium coating. Its karat is measured in the same way, so 18K white gold is 75% gold like 18K yellow gold.
Solid gold does not tarnish or lose its gold content. A piece may get scratched or dirty, but the purity stays the same. Plated items, in contrast, can wear through to the metal below.
