a silver metal clay jeweller’s guide to hallmarking
If you are selling your silver clay jewellery you need to know about hallmarking. Metal clay artist and teacher Anna Campbell has been in touch with the Assay Office to find out up-to-date information and guidelines specifically for metal clay.
What is hallmarking?
Hallmarking is a process of testing and applying a series of marks to your jewellery to verify for your buyer that it is genuine silver. In the UK it is the law that each item of precious metal jewellery you sell, that is over a certain weight, has been officially hallmarked by an Assay Office.
Minimum weights
There are some cases where you are not required to hallmark precious items. This is if they are under the required weight restrictions in the UK. The weight is measured on the metal content and excludes stones.
Weight restrictions
Silver: 7.78 grams (includes metal clay)
Gold: 1.0 grams
Platinum: 0.5 grams
Palladium: 1.0 grams
If your item is under the minimum weight you can still choose to have it hallmarked but it isn’t mandatory to do so.
Weight is measured per element, so a pair of earrings or a pair of cufflinks count as two separate pieces. For bracelets and pendants, if the charms are detachable they count as separate pieces. If they are soldered to the chain or otherwise could not be removed by a non-jeweller it would all counts as one piece.
How is the metal tested?
Technology has advanced so the Assay Offices now try to test the metal with as little harm to the jewellery as possible so it is usually scanned in an x-ray type machine. This allows the tester to see which metal the piece is made of, if there is any plating etc. For larger pieces e.g. chain, they test about 6 times along the length of it to ensure it is all the same metal.
Once the metal is tested the piece will be marked with the official Assay Office stamp, the fineness of the metal and your makers mark (see below).
The Assay Office staff spend most of their time testing mass manufactured pieces being sold in the UK so they love it when they get to work with handmade jewellery!
What does 999 and 925 silver mean?
You will probably know that sterling silver is also known as 925. What this means is that for every 1000 particles of metal, 925 are silver and 75 are copper. The main brands of silver clay are fine silver or 999 meaning that for every 1000 particles - 999 are silver and only one particle is copper - fine silver is purer than sterling silver.
How is 999 fine silver clay hallmarked?
I rang up the Assay Office to ask about this! The majority of us work with the main brands of silver clay which are fine silver or 999. However, your customers are more used to 925 sterling silver. I was informed that if you ask for the piece to be stamped 925 on the hallnote (more on this later) and they test it to find that it is at least 925 pure (which a fine silver clay piece would be) they will stamp it 925. You can also ask for a 999 mark or a Britannia silver mark, which is 958. However, I suggest requesting 925 as this is what buyers are most familiar with.
How are mixed metals hallmarked?
The hallmark of the least precious metal is applied ranking from: silver, palladium, gold, platinum.
E.g. if you have a silver piece with a small amount of gold it will be hallmarked as silver.
Although where possible if you have two metals of a similar size in a piece (e.g. gold and silver) they will add a separate 'fineness mark' to the area with gold.
But the full hallmark will be applied to the silver area.
Can I hallmark jewellery myself?
No. Legally your jewellery needs to be independently hallmarked at an Assay Office. There are four Assay Offices in the UK in London, Edinburgh, Sheffield and Birmingham. You can choose to have your mark at any of these, you do not need to choose the Assay Office nearest to you. The Assay Offices are all separate and do have different prices so it’s worth doing your research as to which will be best for you.
If you choose, you can also mark your items with stamps '925' or '999' yourself although this is not a hallmark.
What marks will my jewellery have?
Sponsors mark - this is your makers mark
Standard mark - the standard of the metal e.g. 925
Assay office mark - the mark for your registered Assay Office
You can also request optional marks including the year and other commemorative marks available at the time of hallmarking.
How do I choose my sponsors mark?
Do your research and decide on which Assay Office you want to register with. I suggest looking at location - especially if you live near one and can deliver and collect your jewellery as this will cut down on your costs. Also look at pricing and which city mark you like best! (Each city has its own mark that will be stamped on your work so this is a legitimate thing to consider!).
You can choose 2-3 letters on your sponsors mark, usually your initials or the initials of your business. They are surrounded by a 'shield' which could be a rectangle, oval or other shape depending on what is available and what you choose. That mark is registered to you and cannot then be used by anyone else even if your Assay Office account lapses. However, your sponsor's mark will only be available at your chosen Assay Office; if you decide to move to another Assay Office you need to register and pay again and your chosen mark may not be available there.
What punch should I choose?
Once you have registered you will choose whether to have a laser mark or a punch. I recommend a laser mark as it is potentially less damaging to a piece than a punch meaning less cleanup once you receive it back. It is also possible to resize the mark based on the size of the piece which is not possible when you have a punch.
However, if you decide to get a punch you can select either a straight and/or swan neck punch. For jewellery, a swan-neck is recommended as it is needed for rings, bangles etc. and can also be used on straight pieces. Go for a small size so that it is sure to fit on a thin ring band.
How do I get my items hallmarked?
It is best to collect together as many items as you can for hallmarking as this makes it more affordable
Fill out a 'Hallnote'. This is a form with your instructions for hallmarking your pieces. Make sure you complete it as fully as you can. If you are having a laser mark ensure you ask for a deep mark as a shallow mark can easily be removed through polishing
Take or post your items in to be hallmarked
Collect or have them delivered back to you
When should I get my hallmark done?
I suggest getting your work hallmarked once the piece is fired but before finishing or stone setting. The process of hallmarking and posting back and forth means you should aim to do the polishing and finishing after it has been at the Assay Office.
What costs are involved?
This depends on which Assay Office you choose. You can find detailed information on each of the Assay Offices websites (see below). Here is an example from the London Assay Office (all costs are correct at time of writing but are subject to change)
Set-up costs:
Registration £72 (lasts 10 years) student discounts are often available
Punch cost from £77.50
Ongoing costs (based on London Assay Office 2022 Price List):
1 – 2 articles in any packet £14
3 or more articles £18 + £1.10 per article
Check shipping and handling fees if you are posting items in
How long does it take?
Allow two weeks.
If you need it sooner there are usually fast-track services with additional costs.
What are the rules about selling my work outside the UK?
I rang up the Assay Office especially to ask about this! The law relates to the country the pieces are being sold to so the laws above are for pieces you are selling to buyers in the UK. However, not all countries have the same laws around hallmarking so, for example, if you were selling a piece of jewellery to a buyer in the USA you do not need to hallmark it regardless of size. In the rest of Europe the guidelines vary depending on the country. For example, if you were selling your work in Ireland you would need to hallmark every piece of silver regardless of size as that is their law.
This is obviously a problem if you are selling online as whether you need to hallmark or not will be governed by the country of the buyer. My advice would be to price your overweight work as though you need to hallmark it. You may still choose to hallmark your pieces regardless of where you are selling to..
Displaying guidelines
If you are selling hallmarked items at a craft fair or event you need to display the dealers notice. This is to give consumers information about the hallmarking process and confirms that you are registered with an Assay Office.
You should also include your dealers notice on your website.
I hope that this has helped demystify the process of hallmarking your silver clay jewellery.
You can find out more from the individual Assay Offices and don’t hesitate to give them a call if you have questions.
The UK Assay Offices
Birmingham Assay Office https://theassayoffice.co.uk/
Edinburgh Assay Office https://www.edinburghassayoffice.co.uk/
London Assay Office https://www.assayofficelondon.co.uk/
Sheffield Assay Office http://www.assayoffice.co.uk/
Anna Campbell is the founder of Jewellery School Scotland and the community manager for Jewellers Academy.
This article was first written for Making Jewellery magazine. It has been updated and is published with the permission of GMC publications.
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