Those tiny stamps inside a ring or on a chain clasp tell you exactly what your jewellery is made of. Here is how to read a UK hallmark before you buy.
Quick look
- A UK hallmark means an independent Assay Office has tested the piece and confirmed it matches its description of gold, silver, platinum or palladium.
- A full hallmark has three compulsory marks: a sponsor’s or maker’s mark, a metal and purity (fineness) mark, and an Assay Office mark.
- Common fineness numbers include 375 for 9 carat gold, 750 for 18 carat gold and 925 for sterling silver, expressed in parts per thousand.
- Items below the exemption weights (7.78 grams for silver, 1 gram for gold or palladium, 0.5 grams for platinum) can legally be sold without a hallmark.
- Jewellers must display a Dealer’s Notice, and online sellers must show hallmarking information, so you always have a reference when checking a mark.
If you have ever squinted at a tiny stamp inside a ring band and wondered what it meant, that little mark is doing an important job. In the UK, it is against the law to describe an item as gold, silver, platinum or palladium unless it carries a hallmark or falls under a small weight exemption. Knowing how to read one helps you buy with confidence and spot pieces that are not what they claim to be.
What a hallmark is and why it exists
Hallmarking has been part of UK history since the 1300s and is one of the oldest forms of consumer protection. Gold, silver, platinum and palladium are usually mixed with other metals to make them strong enough for everyday wear, so it is almost impossible to judge purity just by looking. A hallmark is applied by an independent Assay Office after testing, and it guarantees the item matches its description and meets the legal standard of purity. The rules are set out in the Hallmarking Act 1973, and Trading Standards officers enforce them.
The three marks every full hallmark needs
A complete UK hallmark has three compulsory marks, and all three must be present. If any of them is missing, the piece has not been properly hallmarked.
- The sponsor’s or maker’s mark. This is the registered mark of the person or company that sent the item for testing. Manufacturers, wholesalers, retailers and importers can all be sponsors. In the UK it contains at least two letters, and every mark is unique.
- The metal and purity (fineness) mark. This shows the precious metal content in parts per thousand, and the shape around the number tells you which metal it is.
- The Assay Office mark. This shows which of the four UK Assay Offices tested and hallmarked the item.
Reading the purity numbers
The fineness number tells you the proportion of precious metal in the alloy. Here are the numbers you are most likely to come across.
| Number | What it means |
|---|---|
| 375 | 9 carat gold, at least 375 parts gold per 1,000 |
| 750 | 18 carat gold |
| 925 | Sterling silver |
The shape surrounding the number indicates the metal type, so the same number will always appear inside the same outline for a given metal. Because hallmarks must be applied by an official Assay Office rather than by the maker, testing is independent. Assay Offices use methods such as X-ray Fluorescence (XRF) testing, which measures the elemental makeup of the metal.
Assay Office marks and where your piece was tested
There are four Assay Offices in the UK, each with its own symbol. Birmingham Assay Office, established in 1773, uses an anchor, and millions of pieces have carried that mark. The Assay Office mark is worth noticing because it tells you the piece was tested somewhere with legal duties under UK law, not just stamped by whoever made it.
Optional marks: date letters and other symbols
Alongside the three compulsory marks, you may see some optional extras.
- A date letter indicates the year the item was hallmarked, and it changes on 1 January each year. For example, U indicates 2019. Date letters were compulsory in Britain until 1999, and each Assay Office used its own system until 1975, when they began using the same font and cycle. This is why a letter can mean different years depending on where and when it was struck.
- A traditional fineness symbol depicts the metal in the article.
- A Convention mark comes from the International Convention on Hallmarking, a treaty that encourages cross-border trading of precious metals. The UK has been a signatory since 1972, and an item with a convention mark from a member country is legally recognised here.
When a piece is legally exempt from hallmarking
Very light items do not have to be hallmarked. The UK exemption weights are 7.78 grams for silver, 1 gram for gold or palladium and 0.5 grams for platinum. A delicate pair of gold studs or a fine silver chain may therefore be below the threshold and sold without a mark. That is not a sign of a fake, but it does mean there is no independent guarantee of purity on the item itself, so it is worth asking the seller what the piece is made from and buying from someone reputable. Note that exemption weights vary by country, so the rules can differ if you buy abroad.
How to check before you buy
Little trick: Hallmarks are often tiny. Ask for a magnifying glass in the shop, or zoom in on listing photos before buying online.
Always ask whether a piece is hallmarked. Jewellers must display a Dealer’s Notice explaining the approved hallmarks, which you can use as a reference, and online sellers must show hallmarking information too. It also helps to find out where a seller is based, because legal rights are harder to enforce with a trader outside the UK, and to look for membership of an appropriate trade body. Checking matters: fake jewellery is sold in the UK, and counterfeit pieces can even pose a health risk if they contain dangerous heavy metals. If your skin reacts to unknown metals, our guide to jewellery for sensitive skin explains which materials are usually the safest bet.
Once you have found a properly hallmarked piece, it is worth looking after it so the marks stay legible for years. Our guide to caring for jewellery covers cleaning and storage, and Accessorising 101 shows how to build pieces like these into a finished look without overdoing it.
Ask away
What does 375 mean on gold jewellery?
It is the fineness mark for 9 carat gold, meaning the alloy contains at least 375 parts of gold per 1,000. An 18 carat piece carries the number 750.
Do all gold and silver items have to be hallmarked?
Only items above certain weights must be hallmarked. The UK exemption weights are 7.78 grams for silver, 1 gram for gold or palladium and 0.5 grams for platinum.
What is the date letter on a hallmark?
It is an optional mark showing the year the piece was hallmarked, and it changes on 1 January each year. For example, the letter U indicates 2019.
How can I check a hallmark when shopping?
Ask if the piece is hallmarked and use a magnifying glass, as the marks can be tiny. Compare what you see against the Dealer’s Notice that jewellers must display, or the hallmarking information shown on online listings.
This article is general information, not medical advice. For skin, scalp or allergy concerns, speak to a pharmacist, your GP or a dermatologist. In an emergency, call 999.