Pure gold is too soft for most jewellery. It is mixed with other metals, mainly silver and copper, into an alloy that is harder and holds its shape. The carat number says how many parts out of 24 are pure gold.
| Carat | Pure gold | Stamp |
|---|---|---|
| 9 | 37.5% | 375 |
| 14 | 58.5% | 585 |
| 18 | 75% | 750 |
| 22 | 91.6% | 916 |
| 24 | pure gold | 999 |
Do not confuse this with the carat of a stone, which is a weight: one carat is 0.2 gram. In the United States the gold measure is written karat, as in 14K.
14 or 18 carat
These are the two most used alloys for fine jewellery.
18 carat has a deeper, warmer colour, because three quarters of it is gold. It is heavier, costs more, and is somewhat softer.
14 carat is a little harder and a little paler, and costs less. For a ring that takes a lot of knocks, that hardness is an advantage.
The difference in wear is smaller than is often thought: both last a lifetime when the ring is made sturdily enough. The difference in colour is visible when you hold them side by side.
Habits differ by country
14 carat is the usual choice in the Netherlands and the United States. In the United Kingdom 9 and 18 carat are common. France and southern Europe traditionally work in 18 carat. Germany also uses 8 carat (333). A goldsmith can work in any of them.
What it does to the price
The price of a gold piece follows the amount of pure gold in it: the carat times the weight. An 18 carat ring contains more than a quarter more gold than the same ring in 14 carat, and is slightly heavier as well, because gold is denser than the metals it is mixed with.
Skin and allergies
The higher the gold content, the less of other metals touches the skin. People who react to jewellery usually react to nickel, which is restricted in jewellery in the European Union. See yellow, white and rose gold.
You find the carat stamped in the piece, see hallmarks. Look at yellow gold jewellery by independent goldsmiths.
