The UK hallmark is one of the oldest consumer-protection schemes in the world — assayers’ marks on gold and silver date to 1300. Once you can read a hallmark, valuing an old piece of jewellery or silverware becomes straightforward.
The four required marks
A modern UK hallmark has up to four marks, normally struck side-by-side:
1. Sponsor’s mark
The maker or importer. Two or more letters in a shaped surround — usually rectangular or oval. Every UK Assay Office maintains a register of these; in principle you can look up the maker.
2. Fineness number
The metal’s purity, expressed in parts per thousand (millesimal):
- 999 — fine silver or fine gold (modern bullion bars and coins).
- 958.4 — Britannia silver (Royal Mint Britannia silver coins use 999, but the older “Britannia” silver standard was 958).
- 925 — Sterling silver. By far the most common modern silver mark.
- 916.7 — 22-carat gold (Sovereigns, Krugerrand). Often shown as 916.
- 750 — 18-carat gold.
- 585 — 14-carat gold.
- 375 — 9-carat gold.
See karats / fineness conversion →
3. Assay Office mark
Where the piece was hallmarked. The four current UK offices:
- Leopard’s head — London.
- Anchor — Birmingham.
- Rose — Sheffield (silver only).
- Castle — Edinburgh.
Three offices have closed in living memory — Glasgow (tree-fish-bell, closed 1964), Chester (sword + three sheaves, closed 1962), Newcastle (three castles, closed 1884) — but their hallmarks still appear on older pieces.
4. Date letter
A single letter inside a shaped surround that tells you which year the piece was assayed. Each Assay Office has its own date-letter cycle and font, so the same letter “M” can mean a different year in London vs Birmingham. The shape of the surround (shield, circle, oval) also matters.
For a date-letter chart, the Goldsmiths’ Company website is the canonical reference; online lookup tools like Online Encyclopedia of Silver Marks are useful too.
Optional traditional symbols
Two older symbols you may still see:
- Lion Passant (a walking lion, head facing forward) — historically the mark for Sterling silver (925). Optional since 1999 but most UK silver still carries it.
- Britannia figure — historical mark for Britannia silver (958), used 1697–1720 and again as an optional mark since 1999.
- Crown — historical mark for gold (no specific fineness). Largely obsolete.
The “Common Control Mark”
For international trade under the Vienna Convention, you may see an extra symbol:
- A set of scales (gold), a balance (silver), or a similar mark followed by a millesimal number. This indicates a member-country hallmark accepted across the convention. Recent UK pieces sold abroad often carry it.
A worked example
Imagine you find an old silver teapot with these marks struck side-by-side:
JD · 925 · leopard’s head · shield-shaped m
Reading left to right:
- JD — sponsor (maker or importer initials).
- 925 — Sterling silver, 92.5% pure.
- Leopard’s head — assayed at London.
- m in a shield — the date letter. London’s date-letter cycles repeat every 25 letters; cross-reference the font and shield shape against a London cycle chart. A shield-shaped lowercase “m” in the standard London font matches 1907.
So this is a Sterling silver teapot, assayed in London in 1907, by a maker with initials JD.
What if the metal isn’t hallmarked?
UK law requires hallmarking on:
- Gold ≥ 1g
- Silver ≥ 7.78g
- Platinum ≥ 0.5g
- Palladium ≥ 1g
Below those thresholds, an unmarked piece is still legal. So a tiny 0.5g gold necklace chain might genuinely be 18ct gold without a hallmark — but anything heavier should bear one. Unhallmarked items above the threshold should be treated with suspicion.
Putting it to work
Once you’ve read the hallmark:
- Note the fineness number — e.g. 925, 750, 916.
- Weigh the item in grams.
- Plug it into the calculator using “Custom purity” and your weight.
You’ll get an instant spot-value estimate. Dealer offers will land 10–25% below spot for scrap and a small premium above for collectable pieces.