Know what you hold before you sell it

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• Carat, fineness and hallmarks: how gold purity is actually read

  2026-08-01 · 2 min read

  Carat numbers, millesimal fineness marks and hallmarks all describe the same thing — how much of your item is actually gold. Here is how to read them, and what it means when a piece carries no mark at all.

In the meantime — three things worth knowing

Carat is a fraction of 24

24 carat is pure gold. 22ct is 22 parts gold in 24, usually written as 916 parts per thousand. 18ct is 750, 14ct is 585 and 9ct is 375. The remainder is alloy — copper, silver, zinc — and it is not gold, which is why a heavy 9ct chain can be worth less than a light 22ct one.

A troy ounce is not an ounce

Precious metals are weighed in troy ounces: 31.1035 grams, against 28.3495 grams for the avoirdupois ounce used for everyday goods. That is a difference of about 10 per cent, and it is the most common reason two people quoting the same weight appear to disagree.

What is attached to the gold matters

Stones, clasps, springs, solder and plating all add weight without adding gold. A professional evaluation separates them out rather than weighing the piece whole, which is why an itemised assessment and a single lump figure can differ considerably.