Karat (k)
A measure of gold purity in parts per 24, where 24 karat is pure gold.
Common karats and their fineness
| Karat | Gold content | Fineness mark |
|---|---|---|
| 24k | 99.9% | 999 |
| 22k | 91.6% | 916 |
| 18k | 75.0% | 750 |
| 14k | 58.3% to 58.5% | 585 |
| 10k | 41.7% | 417 |
| 9k | 37.5% | 375 |
In the UK and India the same purity is often written as carat, for example 18ct or 22ct. Jewelry sold in many markets carries a hallmark with the fineness number.
Why the other metals matter
Pure gold is soft, so jewelers alloy it with silver, copper, zinc, nickel or palladium. The mix sets both colour and hardness. More copper gives rose gold, while palladium or nickel produce white gold. Lower karats are harder and cheaper, higher karats look richer and warmer.
Showing karat in renders
A render cannot prove purity, but colour gives buyers a strong hint. 22k yellow gold has a deep, warm yellow, while 14k yellow looks lighter and slightly greener. When you choose a yellow gold material in the studio, pick a tone that matches the alloy you will actually cast, and keep it the same across a collection so customers see the same gold on every product page.
If you sell one design in several karats, render each version as its own colour variant instead of relying on one image and a dropdown. Our metal weight calculator also shows how weight changes between karats for the same CAD volume.