The story of the hallmark

A tavern off the Strand

In 1773, so the story goes, two delegations of silversmiths arrived in London from Sheffield and Birmingham. Both had come to ask Parliament for the same thing: an assay office of their own, so that their candlesticks and coffee pots no longer had to travel to a distant city to be tested and marked. And both, as it happened, were lodging at the same inn, the Crown and Anchor, just off the Strand.

The petitions succeeded, and an Act of Parliament gave each town its office that year. When it came to choosing their marks, the legend says the matter was settled over the inn's sign. Sheffield took the crown. Birmingham took the anchor.

Is any of it true? The Sheffield Assay Office, which knows the story better than anyone, says the inn certainly existed, but whether there is any truth in the tale is unknown. What is certain is that the marks stuck. Birmingham's anchor is still struck today. Sheffield's crown lasted two centuries, until a new law came into force in 1975 and replaced it with the rose that Sheffield had been using on gold since 1904.

Seven centuries of promises

Precious metal has always invited a little creative arithmetic. Pure silver is too soft to make anything useful, so it is mixed with other metals, usually copper, and the temptation to mix in rather more copper than the customer is paying for is as old as the trade itself. Hallmarking was the answer: an independent test, and a mark to prove it had been passed. It is often described as one of the oldest forms of consumer protection in the world, and the dates bear that out.

Notice how little of it has been undone. The leopard's head that Edward I introduced still marks London's work today, more than seven centuries later.

What happens at an assay office

"Assay" simply means test. For centuries the test was done by fire. The assayer scraped a tiny sample from the piece, weighed it, wrapped it in lead and heated it in a small porous cup made of bone ash, called a cupel. The lead and the base metals soaked away into the cup, leaving a bead of precious metal behind. Weigh the bead, compare it with the sample, and the arithmetic tells you exactly how pure the silver is.

Only when a piece passed was it struck with the office's punches, by hand, with a hammer. Fire assay is still the reference method for gold and silver, though modern offices also use instruments that read the metal without harming it, and since 1997 Sheffield has marked pieces too delicate for a hammer with a laser instead.

How to read a modern hallmark

A British hallmark is read from left to right, and on a modern piece it is shorter than you might expect. The law requires three marks. Everything else is optional.

• The sponsor's mark. The registered initials of the person or company that sent the piece for hallmarking, inside a shaped outline. It used to be called the maker's mark, though it never had to be the actual maker.
• The fineness mark. The purity of the metal in parts per thousand. 925 means 925 parts in every 1,000 are pure silver, which is sterling.
• The assay office mark. Which of the four offices tested the piece.

After those, a piece may carry a date letter, showing the year it was marked, which has been optional since 1999. It may also carry a traditional symbol that repeats the fineness in picture form, such as the lion passant for sterling silver. Every so often there are commemorative marks too: a special mark was offered for the Millennium in 1999 and 2000.

The four assay offices

There are four assay offices in the UK today, and each has its own mark.

What the numbers mean

Modern fineness marks use parts per thousand, which makes them easy to compare across metals. A gold piece marked 750 is 750 parts pure gold in every 1,000, the same thing a jeweller would call 18 carat.

When a hallmark isn't needed

Here is the part that surprises people. In the UK, a piece can only be described as silver, gold, platinum or palladium if it has been hallmarked, unless it weighs less than a set amount. Below that weight, no hallmark is needed at all.

So a delicate silver pendant or a fine chain can be perfectly genuine, and perfectly legal, without a single mark on it. The weight counts the precious metal only, not any stones.

Shops that sell precious metal have a duty of their own: they must display a Dealer's Notice, approved by the British Hallmarking Council, explaining the marks to customers. Online sellers are expected to show it on their websites.

Hallmarks abroad

Since 1975 the UK has belonged to the International Convention on Hallmarking. Pieces struck with the Convention's Common Control Mark in one member country are accepted in the others without being tested again, which is why you may find unfamiliar marks on jewellery bought on the Continent. Not every country hallmarks at all, so a missing mark on a piece bought abroad is not, by itself, a reason for suspicion.

Small marks, long memories

Turn over an old silver spoon and you are holding a document. The marks will tell you who sent it to be tested, which office tested it, how pure it is and, very often, the year it was made, all in a strip smaller than a fingernail. Few things we buy carry their history so plainly.

And the tavern? Birmingham's anchor is still struck every working day. Sheffield's crown has gone, but the rose that replaced it is no less proud. Whether the delegations of 1773 really did settle their marks over a pint, the Crown and Anchor's sign lives on in a few millimetres of silver.