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What is a hallmark?

A hallmark is defined as a mark that is stamped on precious metals as a way of certifying their standard of purity. Hallmarks are very detailed and specific. They give information about:

  • who tested the metal

  • on whose behalf it was tested, and

  • what conclusion was reached

Why hallmark jewellery?

Precious metals used in jewellery tend to be used as alloys. This means that the precious metal is mixed with other elements (eg copper, nickel or manganese) to give the piece of jewellery the desired properties (eg flexibility, durability, or affordability).

It is impossible to tell how much precious metal is contained in an alloy by simply looking at it. Because of this, and due to the cost of precious metals, this may lead to fraud. In order to protect consumers and suppliers against any such potential fraud, hallmarking was introduced to confirm that jewellery containing precious metals is genuine.

In order to be hallmarked, items (eg jewellery items) must be submitted to a UK Assay Office or an Assay Office belonging to the International Convention on Hallmarking. Only Assay Offices can stamp items with hallmarks.  

Anyone who sells jewellery that is required to be hallmarked without the applicable marks is breaking the law.

Which metals need to be hallmarked?

There are 4 precious metals that must be hallmarked to be legally sold as genuine (ie to confirm that they meet the legal standard). These metals are gold, silver, platinum and palladium

Items do not need to be hallmarked if they are under the legal weight threshold for the above precious metals. These are:

  • 1 gram for gold

  • 7.78 grams for silver

  • 0.5 grams for platinum

  • 1 gram for palladium

Compulsory marks

Certain compulsory marks must be present on jewellery to indicate that it has been properly hallmarked. These marks are:

  • the Assay Office mark

  • the sponsor’s mark, and

  • the fineness mark

The compulsory marks convey the information that was gathered throughout the testing process. 

All 3 marks must be present. If a piece of jewellery isn’t stamped or marked with all 3 marks, it has not been properly hallmarked.

The Assay Office mark

There are only 4 different Assay Offices in the UK, which are located in London, Birmingham, Sheffield and Edinburgh. The Assay Office will stamp an Assay mark on a specific item of jewellery to identify where the goods were tested and hallmarked and by whom.

From left to right, the above are the Assay marks for London, Birmingham, Sheffield and Edinburgh.

The sponsor’s mark

A sponsor’s mark (also known as a ‘maker's mark’) is a compulsory mark. This is the registered mark of the person, business or other organisation (ie the sponsor) that submits the precious metal or article for hallmarking

Each sponsor must have their own mark that is formed from the initials of the individual or organisation. There must be at least 2 letters and these are typically surrounded by a shield shape. Each sponsor’s mark is unique.

An example of a sponsor’s mark is the London Assay Office mark:

The fineness (or ‘metal and purity’) mark

This compulsory mark is arguably the most important mark within the hallmarking process as it indicates the percentage of the precious metal used in the overall alloy making up the piece. 

The fineness mark sets out how fine (or of what quality) the metal is and the type of metal used. The percentage of fineness is expressed as parts per thousand. For example, 925 silver (also known as Sterling silver) comprises 925 parts of silver per thousand parts of alloy.

Below are the fineness marks currently recognised in the UK:

Optional marks

In addition to the above compulsory marks, there are certain optional marks that can be applied to jewellery. These include:

  • a date letter mark - indicating the year that the piece was hallmarked

  • a traditional fineness mark - traditional standard marks indicating the metal type. These are different to the compulsory fineness marks

  • an international convention mark - the International Convention on Hallmarking implements protective measures for the cross-border trade of jewellery using internationally recognised marks for member countries. If a piece of jewellery is marked with a convention mark from one of the member countries it is legally recognised in the UK without needing to be specifically hallmarked before sale in the UK

  • a commemorative mark - these are special hallmarks that celebrate major events (eg a coronation)

What is the hallmarking process?

Hallmarking is most common for jewellers working with precious metals as a part of their trade; although anyone can have a metal item hallmarked if they wish to.

The process of hallmarking is relatively straightforward and involves:

  • registering with your local Assay Office and paying the appropriate fees (remember that Assay Offices work independently, so if you want to register with all 4 Assay Offices you will have to pay the fees 4 times)

  • sending the items you require to be hallmarked to your chosen Assay Office

  • hallmarking at the Assay Office, specifically:

    • your precious metal piece being awarded the correct Assay mark

    • your unique and individual sponsor’s mark being added

    • the fineness mark being stamped onto your item after the Assay Office has fully evaluated the percentage of precious metals

Jewellery is hallmarked with either stamps or lasers. Traditionally, marks were stamped into jewellery. Nowadays, most jewellery is marked using lasers as this does not distort the jewellery and may be very subtle (ie often difficult to see without a loupe).

Things to remember

Although the process of getting your precious metals hallmarked is easy enough to do, it’s not without risks. Precious metals are by definition precious, so there is always a risk that your goods could be stolen during transit. Sending your precious metals to your nearest Assay Office reduces the amount of time they are in transit and, as a result, minimises the chance of something being stolen.

It is also important that you fully understand the pricing system of your chosen Assay Office so that you don’t face any financial surprises. Remember that you will be charged per item, so for a pair of earrings, you will be charged twice.

For more information, see the government’s guidance on hallmarking and do not hesitate to Ask a lawyer if you have any questions.


Tom Ginever
Tom Ginever
Director & Gemologist at Jollys Jewellers

Jollys Jewellers are a family-run chain of jewellery stores in the UK specialising in vintage and antique jewellery, established in the 1830s.

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