Look for the hallmark
A hallmark is the oldest form of consumer protection in Britain — an independent test, struck into the metal, that the piece is what it is sold as. Every precious metal article we make is hallmarked before it reaches you.
Dealer’s Notice
Look for the Hallmark — it’s your guarantee
In the UK it is illegal to supply or offer to supply any item as gold, silver, platinum or palladium unless it is hallmarked. Exemption weights apply: 7.78g silver, 1g gold and palladium, 0.5g platinum.
- The sponsor's mark
- Whose piece it is — the registered mark of the company that put the article on the market. Ours is registered with the London Assay Office.
- The fineness mark
- How much precious metal is in it, in parts per thousand. 750 is 18ct gold, 375 is 9ct, 950 is platinum. The shape around the number tells you which metal it is.
- The assay office mark
- Who tested it. A leopard's head is London, an anchor Birmingham, a rose Sheffield, a castle Edinburgh.
International hallmarks must contain the scales of the Common Control Mark. Displayed in accordance with the Hallmarking Act 1973. Read the full Dealer’s Notice (British Hallmarking Council).
What a hallmark certifies — and what it doesn’t
It certifies the metal
An assay office independently tests the article and strikes the marks itself. That is a guarantee of fineness — that your 18ct ring really is 750 parts per thousand gold, tested rather than asserted.
It says nothing about the stone
A hallmark is not a diamond certificate and the two are often confused. Your diamond’s cut, colour, clarity and origin come from its grading report — GIA for natural stones, IGI for most laboratory-grown ones — which is a separate document entirely.
Legal fineness standards
- Gold
- 375 (9ct) · 585 (14ct) · 750 (18ct) · 916 (22ct) · 990 · 999
- Silver
- 800 · 925 (Sterling) · 958 (Britannia) · 999
- Platinum
- 850 · 900 · 950 · 999
- Palladium
- 500 · 950 · 999
No engagement ring is ever light enough to fall under an exemption weight — a plain platinum shank alone is several times the 0.5g threshold — so every ring we make is hallmarked, without exception.
How to read the marks on your own jewellery
Find them inside the shank of a ring, on the clasp or the tag of a chain, or on the case back of a British-cased watch. Under a loupe there are three compulsory marks, sometimes with two more beside them. Read left to right.
The number — what the metal is
- 375
- 9 carat gold — 375 parts gold per thousand
- 585
- 14 carat gold
- 750
- 18 carat gold — what most engagement rings are
- 916
- 22 carat gold
- 925
- Sterling silver
- 958
- Britannia silver
- 950
- Platinum, the usual jewellery standard — or palladium
- 999
- Fine gold or fine silver, effectively pure
The shape of the shield around the number tells you which metal it is before you have read the number at all: gold sits in a rectangle with clipped corners, silver in an oval, platinum in a shape like a house on its side, palladium in three joined circles.
The town mark — where it was tested
- London
- A leopard's head
- Birmingham
- An anchor
- Sheffield
- A rose
- Edinburgh
- A three-towered castle
Those four are the offices still operating. A mark you cannot match to any of them may be from an office long closed — Chester, Exeter, Newcastle, Glasgow, Dublin — which usually means the piece is older than the office’s closing date, and that is often the most interesting thing about it.
The letter — when it was tested
The date letter is optional now and has been since 1998, but it was compulsory for centuries and it is on almost anything old. One letter per year, the typeface and the shield around it changing each time the alphabet restarts, which is what makes a letter datable rather than merely a letter. Bring a piece in and we will read it with you.
The Assay Office is in Hatton Garden
The London Assay Office keeps a counter at 17 Greville Street, London EC1N 8SQ — which is Hatton Garden, a few minutes’ walk from the bench a piece is made on. Its main office and the address everything is posted to is Goldsmiths’ Hall on Gutter Lane in the City, but the Greville Street counter is why this quarter works the way it does: a ring can be finished, walked round, tested, marked and walked back inside a morning.
It is also why a hallmark from a Hatton Garden workshop is rarely a delay. When a jeweller tells you hallmarking will add weeks to a commission, they are usually telling you their bench is a long way from an assay office.
Resizing and repair
Altering a hallmarked article is regulated too. Adding a little metal to size a ring up is permitted within set limits; removing metal to size it down is an alteration, and an improperly repaired article is treated in law as though it were unhallmarked. We handle this through the London Assay Office as a matter of course — but it is the reason a resize is a conversation with the workshop rather than something to be done on a high street in twenty minutes.
FAQS
750 parts of gold per thousand, which is 18 carat. The number on a British hallmark is always fineness in parts per thousand rather than carats, so 375 is 9 carat, 585 is 14 carat, 750 is 18 carat and 916 is 22 carat. On silver, 925 is sterling.
Anything sold as gold must be, above one gram. The exemption weights are 1g for gold and palladium, 0.5g for platinum and 7.78g for silver — and no engagement ring comes near them, since a plain platinum shank alone is several times the platinum threshold. Below those weights an article may be sold unmarked; above them it is an offence.
A leopard's head for London, an anchor for Birmingham, a rose for Sheffield and a three-towered castle for Edinburgh. Those are the four offices still operating. A mark matching none of them is likely from a closed office such as Chester, Exeter, Newcastle, Glasgow or Dublin, which dates the piece before that office shut.
Its main office is at Goldsmiths' Hall, Gutter Lane, London EC2V 8AQ, and it keeps a counter at 17 Greville Street, London EC1N 8SQ — inside Hatton Garden. Consignments are posted to Goldsmiths' Hall rather than Greville Street. Having the counter in the jewellery quarter is why hallmarking a piece made here is a walk rather than a wait.
No, and the two are often confused. A hallmark is an independent test of the metal only — it says nothing whatsoever about the stone. A diamond's cut, colour, clarity and carat come from a separate grading report, usually GIA for a natural stone and IGI for most laboratory-grown ones.
Usually, but it is regulated. Adding metal to size a ring up is permitted within set limits; removing metal to size it down counts as an alteration, and an improperly repaired article is treated in law as though it had never been hallmarked at all. We put resizes through the London Assay Office as a matter of course.