Hallmarking and Assay testing


A hallmark comprises three compulsory marks, the standard (fineness) mark, the office (place) mark and the sponsor's (maker's) mark. These are stamped (or laser-engraved) into the metal by an assay office. Please see the best price for gold hallmark chart.

The first compulsory mark is the standard mark. This shows the purity (fineness). To establish the purity a scraping is taken and analysed. However, the exact fineness isn't marked, only one of a handful of 'standard' finenesses. For gold these are (in parts per thousand and carat): 375 (9ct), 585 (14ct), 750 (18ct), 916 (22ct); and also 990 and 999 (marked in parts per thousand only). For silver these are (in parts per thousand)800, 925,958 and 999.




The process of analysing a metal is called an 'assay'. The only organisation permitted to mark precious metals with hallmark stamps is The Assay Office. It is illegal for anyone else to mark precious metals, even possessing a punch that reads 9ct is illegal.

The next part of a compulsory hallmark is the Assay Office mark which shows where the item was assayed.

The third compulsory mark is the sponsor's (maker's) mark, usually their initials. Manufacturers must have their mark registered with an Assay Office. For a member of the public the Assay Office will use their own sponsor's mark, eg. BAO for Birmingham Assay Office.

Date letters (recorded since 1544) have not been marked on very small items since 1984 and have not been compulsory at all since 1999.

Any assay office will verify a hallmark (tell you if it's genuine) free of charge. Full assaying and hallmarking are not expensive. For a fee of around £25 a basic service will take a few days, there are many other options, you can even have an item hallmarked in an hour if you're prepared to spend over £50.00.

Anyone can send items to be hallmarked but a trader or scrap gold buyer must have their name registered and a Sponsor's Mark stamp made. The cost of registration is around £100.00 and lasts ten years

Gold items are hallmarked 375, 585, 750, 916, 950 and 999 only: any item which just fails a test will be marked down a grade. An item submitted as 585 (14ct) which is less (eg. only 13.9 ct) will be marked 375 (9ct). If you have some Arab 21 ct gold you might assume that it will be more saleable with a UK hallmark, but beware, if, at the Assay Office, it fails the 22ct test it will be hallmarked 18ct!

Items made since 1973 must, by law, be hallmarked. Exceptions are made for very lightweight items. The law states that items which are not hallmarked must not be described as gold, a problem for traders trying to sell antique items which are not hallmarked. Even the description of an item as 'stamped 18K' led to prosecution because the jeweller implied that the item was gold (which, of course, it was). If a trader tests an item in front of you and proves it is gold, then the facts of chemistry are indisputable, but do not expect a written receipt stating that it is gold.

A useful pocket book is the Dealer Guide, English Silver Hallmarks which enables the dating of British hallmarked items from 1544. The same date letters apply to both gold and silver.

There is a also book of international silver marks published by Tardy (International Hallmarks on Silver, collected by Tardy) which includes an ingenious index showing marks in picture-order, since you will not be able to look up a mark under Country if you don't know which country the mark comes from.

The official hallmark chart must, by law, be displayed by everyone who trades in precious metals (gold, silver, platinum or Palladium), and this applies to anyone who buys or sells precious metals, whether in a shop, market, antiques fair or even a boot sale.

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