Precious Metals & Karat
Gold, silver, platinum and palladium — what sets them apart, and what the numbers stamped on them mean. Pure gold is too soft to wear, so it's mixed with other metals; how much gold remains is its karat.
Karat & fineness
Karat measures gold purity in twenty-fourths — 18K is 18 parts gold out of 24, or 75%. Fineness says the same thing in parts per thousand: 750. (Karat the purity is not carat the gem weight.) Here's how they line up.
Hallmark Calculator
Translate a purity you know into how any country marks it — gold, silver, platinum, palladium — or compare two countries side by side.
The four metals
Gold
24K / 18K / 14K / 9KNever tarnishes; too soft pure, so it's alloyed. Comes in yellow, white and rose.
Silver
925 sterling (usual)Bright and affordable, but reacts with sulphur in air and tarnishes over time.
Platinum
950 (usual)Dense, naturally white, and hypoallergenic. It doesn't wear away — it develops a patina.
Palladium
950 / 500A lighter, lower-cost platinum-group metal; naturally white. UK-hallmarked since 2010.
Gold colours
The metals mixed into gold change its colour, not just its strength.
- Yellow gold
- Gold with silver and copper — the classic warm tone.
- White gold
- Gold with white metals (palladium or nickel), usually rhodium-plated for a bright white.
- Rose gold
- Gold with a higher copper content for a pink blush.
Silver standards
- 999
- Fine silver — Soft; bullion and some jewellery
- 958
- Britannia — A higher standard
- 925
- Sterling — The everyday standard
- 900
- Coin silver — Older / continental
- 800
- Continental — A lower standard