Gold, silver, platinum and palladium look and feel much like the alloys that imitate them. Their content cannot be judged by sight or touch, and that is the reason the UK has a hallmarking system at all. A hallmark is an independent assay office’s confirmation that an article has been tested and is at least the fineness it claims. This guide explains how the system works, using the Hallmarking Act 1973 and the practical guidance the four UK assay offices publish together (their Hallmarking Guidance Notes, November 2022, published on GOV.UK).
The law is about description
The main offence under section 1 of the Hallmarking Act 1973 is not making or owning an unmarked article. It is describing one. A person acting in the course of a trade or business commits the offence if they describe an unhallmarked article as being wholly or partly made of gold, silver, platinum or palladium, or supply or offer to supply an unhallmarked article to which such a description is applied.
The assay offices’ guidance spells out three consequences that are easy to miss:
- A description can be spoken, written, or a stamp. A manufacturer’s fineness mark such as “925” on a piece of jewellery counts as a description. A stamp is not a hallmark, and it does not replace one.
- It covers pre-owned articles too. The requirement applies equally to new and second-hand pieces.
- It covers every channel. It applies to anyone trading with UK consumers, whether online, by distance selling, on a market stall or in a shop.
A private individual selling their own jewellery is not acting in the course of a business, and the offence is framed around trade. The marks are still the best evidence of what a piece contains, whoever is selling it.
The three compulsory marks
A UK hallmark is made up of three compulsory symbols:
- The sponsor’s mark. This identifies the maker, or the business that sent the article for hallmarking. In the UK it consists of at least two letters inside a surround, and no two sponsor’s marks are the same at any one assay office. Section 2(4) of the Act treats an article as unhallmarked if it lacks the approved hallmarks and the sponsor’s mark.
- The metal and fineness mark. A number in parts per thousand states the minimum precious metal content, and the shape of the surround shows which metal it is. 750 in the gold surround means at least 750 parts per thousand gold, which is 18 carat.
- The assay office mark. This shows which office tested and marked the article. There are four: London (a leopard’s head), Birmingham (an anchor), Sheffield (a rose) and Edinburgh (a castle). The assay office marks page shows each one with its history.
The fineness mark is a minimum, not an average. An article marked 925 has been tested and found to be not less than 925 parts per thousand silver. The standards a UK hallmark can state are fixed in the Act:
- Platinum: 999, 950, 900, 850
- Gold: 999, 990, 916, 750, 585, 375
- Palladium: 999, 950, 500
- Silver: 999, 958, 925, 800
The gold purity converter turns each gold standard into carats, and the silver purity guide sets the UK silver standards beside those of other countries.
The optional marks
Alongside the compulsory hallmark, a sponsor can ask for further marks:
- Traditional fineness symbols. These are the older pictorial marks. The assay offices list symbols for sterling silver (with a separate Scottish version), Britannia silver, gold, platinum and palladium. They are now optional and sit beside the millesimal number. They do not replace it.
- The date letter. Until 1999 the date letter was compulsory. Now it can be applied voluntarily, and it changes once a year on 1 January. Reading an old date letter means knowing which office and which cycle it belongs to, together with the letter’s typeface and shield. This site does not yet publish those tables, because they have not been sourced from an assay office reference.
- Commemorative marks for particular years or events, when an assay office offers them.
The Convention mark
The UK has been a signatory to the International Convention on Hallmarks since 1972. UK assay offices can strike the Convention hallmark, and Convention hallmarks struck in other member countries are legally recognised in the UK without being re-hallmarked. A Convention hallmark consists of four marks: the sponsor’s mark, the common control mark (a pair of scales), a fineness mark and an assay office mark. The Convention marks page lists the finenesses the Convention recognises.
What does not need a hallmark
Articles under a minimum weight are exempt. The thresholds are 0.5 g for platinum, 1 g for gold and for palladium, and 7.78 g for silver. Where an article mixes precious and base metal, the weight that counts is the total metal weight, base metal included. Where it contains more than one precious metal, the threshold is the one for the most precious metal present. The hallmark exemption checker applies these figures to a weight you enter.
Age is the other main exemption. An article that can be shown to be of minimum fineness and made before 1950 may be described and sold as precious metal without a hallmark. The cut-off date was 1920 from 1999 until the legislation was amended. Further exempt categories, listed in full in the Guidance Notes, cover certain articles too heavily set or engraved to mark, and the settings of stones.
What a hallmark does not tell you
A hallmark measures metal, and only metal. It says nothing about the stones in a piece, its maker’s reputation, its condition or what anyone will pay for it. The gold in a hallmarked ring can be calculated from its weight and fineness mark, and the scrap gold calculator does that at the live price. That melt figure is the value of the metal, not the value of the ring. If a mark looks wrong, the guide on spotting a fake hallmark covers what to check, and an assay office can test a piece directly.