If I want to sell my silver clay jewellery, do I need to get it hallmarked first? If so, how do I go about it?


In short if you’re in the UK: yes, unless the finished silver piece weighs less than 7.78g. If you are not in the UK, please check what local laws apply.

If the finished silver piece weighs more than 7.78gm it is a legal requirement to get it hallmarked if you trade and describe it as silver.

The weight limit doesn’t include stones, resin, or other non-silver parts.

A UK hallmark tells you what material/fineness the piece is, who made it, and where it was marked. It adds some authenticity to your jewellery, reassures your customers, and it also allows you to be recognised as the maker many, many years later. Hallmarking in the UK goes back as far as to the early 1300s!


You can’t hallmark your own pieces, it has to be done through an assay office. You send your pieces in and they are tested to confirm the material is what you say it is, and then marked up.

There are four Assay Offices in the UK to choose from when you register; London, Birmingham, Sheffield, and Edinburgh.

They are all independent companies so charges and processes vary slightly from office to office. It can be worth doing some comparisons to ensure you find the one with the best fit for you. Whilst comparing fees, you might also want to ask;

  • what marks are applied
  • how long does the marking take
  • how do they want the work supplied
  • is there a packaging/unpackaging fee? Will they charge for opening poly bags, or unwrapping tissue paper?
  • and how they want the pieces marked up showing where the mark should go

A complete hallmark consists of three compulsory punch marks:

1. Sponsor’s mark – a unique mark which identifies who sent the piece in for hallmarking – usually the person who made the piece, and usually the stamp consists of the maker’s initials or company name. This used to be called a Maker’s mark.

2. Standard (or Fineness) mark – this shows what material it is, and what fineness. For silver clay this would usually be 999 (i.e. 99.9% pure silver) for the fine silver clays, or 958 (Brittania) or 925 (Sterling) for the sterling type clays.

3. Assay Office mark – this symbol shows which office tested and marked the piece; for instance a lion for London and an anchor for Birmingham.

There are also two optional marks that are sometimes applied; a traditional fineness mark (symbol rather than numbers, like, a lion for Sterling Silver) and a date mark letter – again, if this is done, and if there is a cost, varies from office to office.


You need to choose an Assay office to register with. They are all independent. When you register you’ll get a unique Sponsor’s mark punch made up for you. This is usually kept at the Assay Office.

You can also get a Laser Sponsor Mark for products that might be too delicate to punch mark. There is an additional fee for this, contact the Assay office for more information about this.

It costs about £70 to register for ten years and the punch starts at about £120 (if you are a full time jewellery/silversmithing student there are discounts – have a chat to your tutor!).

You then send your jewellery to the Assay Office, where they test the purity of the metal. This is usually done by X-ray fluorescence technology. Once they’ve confirmed it is the material and fineness you say, they’ll apply the hallmarks.


This varies from office to office, but you usually pay a fee per packet you send in with a minimum charge applied. If you want your pieces to be laser marked rather than punched there is an extra fee. There is also a fee for return postage, express services, and sometimes, a handling charge. It is usually cheaper to send a batch and mark several items in one go.

Here we have covered the basics about hallmarking. When you sign up you will get more detailed information – we recommend you read this before sending in your work. There is guidance when it comes to combined materials, using solder or adhesives, and more – here is a very helpful document, with lots of information.

Hope this helps!

Happy making,
The Metal Clay Ltd Team x

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