The four offices
| Assay office | Town mark |
|---|---|
| Goldsmiths' Company Assay Office, London | Leopard's head |
| Birmingham Assay Office | Anchor |
| Sheffield Assay Office | Rose |
| Edinburgh Assay Office | Castle |
All four are supervised by the British Hallmarking Council. A mark from any of them carries the same legal standing — a Birmingham anchor does not indicate a lesser or greater standard than a London leopard's head.
Historic offices you may come across
Older British jewellery can carry marks from offices that have since closed, including Chester, Glasgow, Exeter, Newcastle, Norwich and York. Chester in particular turns up on pieces circulating in North Wales and the north west, because the office served the region until it closed in 1962. A closed office's mark is still a genuine hallmark.
Marks applied outside the UK
Items hallmarked abroad under the International Convention on Hallmarking carry a Common Control Mark and the striking office's own mark. Many imported pieces carry no hallmark at all, only a maker's fineness stamp — common on jewellery bought in the United States, the Middle East and South Asia.
Why the office mark matters when selling
It rarely changes the metal value, which follows weight and purity. It matters for identification: a full hallmark set — sponsor, fineness, office, date letter — lets a piece be dated and attributed, which occasionally means an item is worth more intact than as scrap gold.
Date letters and dating a piece
A date letter records the year an item was hallmarked. All four UK offices have used the same letter since 1975, changing every 1 January, with a fresh alphabet — new typeface, case and shield shape — issued every twenty-five years. The current series began in January 2025. Date letters have been voluntary since 1999, so a recently marked piece may carry none at all.
The same 1999 change gives a useful dating shortcut. Millesimal fineness became the compulsory fineness mark then, replacing the older crown-plus-carat numeral. A gold item marked with a crown and a bare 9 or 18 was hallmarked before 1999; one carrying only 375 or 750 was hallmarked after it.
When there is no assay office mark at all
Light articles are exempt from hallmarking: for gold the threshold is one gram, so small studs, thin charms and infant rings are frequently unmarked despite being solid gold. An absent mark is not evidence of plating: the one-gram exemption means a great deal of small solid gold carries no mark at all.
Sources
- Hallmarking guidance notes published by the UK assay offices and the British Hallmarking Council; Hallmarking Act 1973 as amended.
