UK Gold Hallmarking Explained: What 375 Means

UK hallmark stamped inside a Collective & Co. solid 9ct gold piece

hallmarking

Proof it's real gold

A hallmark is a tiny set of marks stamped onto precious metal jewellery after it has been independently tested by an Assay Office. It's a guarantee that your piece is made of the metal and purity it says it is.

In the UK, hallmarking is the law. Gold jewellery weighing over 1g must be hallmarked before it can be sold as gold, whether it's bought in a shop or online. Every 9ct gold piece we sell over 1g carries a UK hallmark from the Assay Office.

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How to read a hallmark

Every UK hallmark has three compulsory marks. Together they tell you who sent the piece for testing, what it's made of and where it was tested.

Who
The sponsor's mark
Initials inside a shield, identifying the business that sent the piece to be hallmarked. Ours is our Collective & Co. C&C.
What
The fineness mark
The metal and its purity in parts per thousand. On our 9ct gold pieces you'll see 375, which means 9ct gold.
Where
The Assay Office mark
The symbol of the office that tested it: a leopard's head for London, an anchor for Birmingham, a rose for Sheffield or a castle for Edinburgh.

Marks you might also see

A crown: the traditional symbol for gold, shown next to the fineness mark.
A date letter: shows the year the piece was hallmarked. It's optional, so not every piece has one.
The Common Control Mark: a mark recognised across the countries in the International Hallmarking Convention.

Which of our pieces are hallmarked?

UK law sets a minimum weight of precious metal before a hallmark is required. Stones and other materials don't count towards the weight.

Material	Hallmark required when	What the hallmark shows
9ct gold	It contains more than 1g of gold	375 (9ct gold), applied by the London Assay Office
Gold vermeil	It contains more than 7.78g of silver	925 (sterling silver), as the gold is a surface layer
Gold-plated sterling silver	It contains more than 7.78g of silver	925 (sterling silver), as the gold is a surface layer

Many delicate pieces, like small studs and fine huggies, weigh less than these limits, so they don't need a hallmark by law. Every product page lists the metal and its weight.

Hallmarking questions

Where is the hallmark on my piece?

Usually somewhere discreet: on the inside of a ring band, on an earring post or the inside of a huggie, or on a necklace clasp or tag. It's very small, so a magnifying glass or your phone's zoom helps.

My piece doesn't have a hallmark. Is it still real gold?

If it weighs under 1g of gold, the law doesn't require a hallmark, so many delicate pieces don't have one. Every product page states the metal and its weight, and you're welcome to contact us if you'd like to check.

Why isn't gold vermeil or gold-plated jewellery hallmarked as gold?

Because the gold is a layer on the surface. These pieces are made from sterling silver, so if they're heavy enough to need a hallmark, it shows 925 for sterling silver.

Is a foreign gold stamp the same as a UK hallmark?

Not always. A maker's stamp such as "375" or "9K" isn't a hallmark on its own. UK law recognises hallmarks from UK Assay Offices and the Common Control Mark from International Hallmarking Convention countries.

Who checks hallmarking?

The UK's four Assay Offices, in London, Birmingham, Sheffield and Edinburgh, test and hallmark precious metal. The British Hallmarking Council oversees the system, and Trading Standards enforces the law.