In the UK, it is illegal to sell any item like gold, silver, platinum or palladium unless it has been hallmarked. The hallmark represents one of the oldest forms of consumer protection. Jewellery, bullion, (or any other item) that is described as gold, silver, platinum or palladium must have a hallmark to guarantee its authenticity, quality, and precious metal content. This article will explore these symbols and what they represent.


Compulsory Marks

The hallmark comprises three compulsory marks; a sponsor’s symbol, a fineness symbol, and an assay office symbol. It is possible to find additional symbols, but these will be outlined later. There will always be three main symbols to look out for, these are:


1. Sponsor’s Symbol

The sponsor’s mark is the registered mark of the individual or company who has submitted the item for hallmarking to the assay office. If you are lucky enough to own Bleyer’s special hand-poured silver charity owl bars, you’ll know that the mark for this is represented as ‘BYB’ (the official mark of hand-poured producer, Backyard Bullion).


Read more in ‘Hand Poured Silver Charity Owl Bars Exclusive to Bleyer’ here.


Hallmark Square Owl Bar


2. Assay Office Symbol

There have been many assay offices in the past, but today in the UK, a hallmark is struck in one of four independent assay offices. They test the purity of precious metals, protect consumers from buying fake items. If an item conforms with the legal requirements for purity, the Assay Office marks it with the appropriate symbols.


The 4 Main Assay Offices in the UK:

  1. Birmingham Assay Office
  2. Edinburgh Assay Office
  3. London Assay Office
  4. Sheffield Assay Office


Hallmark Assay Office

Did you know – The Goldsmiths’ Company Assay Office, in London, began hallmarking in 1327, making it the oldest assay office in the UK?


3. Fineness Symbol

The Fineness mark shows the precious metal content in the item. It’s recorded in parts per thousand. This means that the number tells you the percentage of precious metal content, and if it is an alloy. For example, the fineness mark of 9-carat gold is 375. This tells us that the alloy must have at least 375 parts gold per 1000. The metal type is indicated by the shape the number is surrounded by.


Hallmark Assay Office


Optional Marks

There is a selection of other markings that can be found on hallmarked gold and silver. These include; fineness symbols, a date letter, and an international convention mark.


1. Traditional Fineness Symbol

These are small symbols that will also tell the contents of the precious metal. These symbols represent sterling silver, Britannia silver, gold, palladium, and platinum.


Hallmark Traditional Fineness Symbols

(Source: London Assay Office)


2. Date Letter Symbol

This mark is used to determine how old it is. The hallmarked letter depends on the year of when the metal was hallmarked.


Hallmark Date Letters


3. International Convention Symbol

This mark is used by countries that are signatories to the ‘International Convention on Hallmarking’. Countries such as the UK, Hungary, Slovenia, Austria, Portugal and Norway, as well as many more, are all members, and therefore officially recognise this symbol.

Some marks of member countries of the Convention are shown below. The shield design around the number may vary according to whether the article is gold, silver or platinum.


Hallmark International Convention Marks

(Source: Birmingham Assay Office)


Reputable Sources

If you are buying online, hallmarking law still applies. Make sure you know where the seller is based. Make sure you protect yourself by buying from a reputable seller. Whether buying in a shop or online, look out for a sign indicating that the seller belongs to an appropriate trade body. What do you do if it is not hallmarked? Contact your local Trading Standards Authority. For more information, please visit the British Hallmarking Council.

We are extremely proud of Bleyer’s own charity silver owl bars, made by Backyard Bullion and hallmarked in Edinburgh. You can purchase them via our website or by calling one of our friendly Bleyer team on 01769 618618.


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