What you need to know about Hallmarking.

What is a Hallmark?

In 1973 The Hallmarking Act was introduced, this meant that all goods made from precious metal i.e gold, silver, platinum or palladium, must be hallmarked to accurately determine the purity of the metal before sold in the UK.

Guide to Hallmarks


A hallmark is a government seal of approval which is stamped onto these precious metals to certify the quality of the metal. This process is known as 'assaying' (testing) and can only be carried out by a UK Government Assay Office. This testing process means that all precious metals sold in the UK will be granted with a hallmark when they conform to legal standards of pureness and gives goods provinence by telling us who sent the item for hallmarking, where it was hallmarked and importantly what it is made from. 

It is a criminal offence to misrepresent the metal or quality of precious metals in the UK or to counterfeit, alter, remove or deface a hallmark. 

 When did Hallmarking Begin?

Hallmarking began in 1327 in London where the first assay office was opened. More assay offices opened across Britain to accommodate demand, each with a unique mark. 


Guide to Hallmarks- Assay Office

Nowadays there are only four working Assay Offices in Britain, located in London, Birmingham, Sheffield and Edinburgh. On antique pieces you may find the hallmarks of Chester, Exeter, Glasgow, Newcastle, Norwich and York.


Hallmarking Assay Offices


Hallmarking protects both merchants and consumers of precious metals in all its forms and is one of the oldest methods of consumer protection. It is impossible to know the quality of a metal simply by looking at it so the hallmarking process is crucial in ensuring industry wide quality is adhered to and honest trading takes place. 

What Does a Hallmark Look Like?

A Hallmark must consists of at three marks:

The Sponsor's mark ( or the makers mark)

 The registered mark of the company that submitted the item for hallmarking. This is the initials of the company within the shape of a shield. 

The Assay Office mark

This mark tells you which Assay Office tested and hallmarked the item. 

 The Fineness mark

This part of the hallmark tells you both the type and quality of the metal. 

 Other voluntary marks can be added such as the Date Letter mark and symbols which indicate different metals. 

How are Hallmarks Decided?

 The precious metal content of the item must be confirmed. Traditionally this was both a long and destructive process which involved . . . 

Gold cupellation - A 2000 year old process where the pure gold is separated from the base metals in order to determine the overall amount of pure gold.

Touch Testing - a tradition dating from 500BC. Here the item is lightly rubbed against basonite leaving a smear of the metal. Chemicals are then applied and depending on the reaction the fineness of the metal is determined. 

However these days less obstructive means of assaying metals are used by X-ray Fluorescence Spectroscopy (XRF) which can accurately determine the finess of metal in under 30 seconds. 

 How are Hallmarks Applied?

 The way in which a hallmark is applied will depend on the item itself. Usually the method of application will be governed by the The Assay Office choice. 


Guide to Hallmarking


Some goods will be hand marked or marked with the help of a hand operated hydraulic press to mark the metal. Today it is increasingly common that a hallmark will be imprinted by the use of laser technology. Laser marking is best suited to delicate items which may feature more precious stones or more complex designs or which are hollow and would not withstand a traditional punch mark by hand. 

 Are There Any Exceptions?

Yes! Whilst it is a criminal offence not to hallmark items made from precious metal it excludes very small items which fall under a certain gram weight. No hallmark is necessary for gold under 1 gram, platinum or palladium under 0.5gram or silver under 7.78 gram.

This means that you will not find a hallmark on smaller pieces of jewellery such as small stud earrings.