How Do You Read the Hallmark on a Ring?
UK hallmarks have 3 compulsory marks: sponsor, fineness and Assay Office. 750 is 18ct gold, 925 sterling silver and 950 platinum. Date letters are optional.
A UK hallmark on a ring is read as three compulsory marks: the sponsor’s mark showing who sent it for testing, a number such as 750 showing the metal’s purity in parts per thousand, and the Assay Office mark showing where it was tested. A date letter may also appear, but it has been optional since 1999. Look inside the band with a magnifier.
What are the three compulsory marks in a UK hallmark?
The three compulsory marks in a UK hallmark are the sponsor’s mark, the fineness mark and the Assay Office mark. The sponsor’s mark is at least 2 letters inside a shaped outline and identifies the maker or the business that submitted the ring. The fineness mark is a number giving the precious metal content. The Assay Office mark shows which of the 4 UK offices tested and struck it.
The rules come from the Hallmarking Act 1973, explained in the UK government’s hallmarking guidance notes of November 2022.
What do the numbers 375, 585, 750, 925 and 950 mean?
The numbers 375, 585, 750, 925 and 950 in a hallmark are millesimal fineness marks, meaning parts of pure metal per thousand. In gold, 375 is 9ct, 585 is 14ct and 750 is 18ct. In silver, 925 is sterling silver. In platinum, 950 means 95% pure. The outline drawn around the number also tells you the metal, because gold, silver, platinum and palladium each have their own shape.
The trade-offs between those gold purities are set out in how many carats of gold suit a wedding ring, and sterling silver in whether 925 silver suits wedding rings.
In short, the number tells you the purity and the outline around it tells you the metal.
| Fineness mark | Metal | Common name |
|---|---|---|
| 375 (37.5% gold) | Gold | 9ct gold |
| 585 (58.5% gold) | Gold | 14ct gold |
| 750 (75% gold) | Gold | 18ct gold |
| 925 (92.5% silver) | Silver | Sterling silver |
| 950 (95% platinum) | Platinum | Platinum 950 |
How do you tell which Assay Office tested a ring?
The Assay Office that tested a ring is shown by its town mark, one of 4 symbols. London uses a leopard’s head, Birmingham an anchor, Sheffield a Yorkshire rose and Edinburgh a castle. The town mark sits beside the fineness mark, usually inside the back of the band, and is often less than 1 mm tall on a slim ring, so a 10x jeweller’s loupe helps.
Which optional marks might also appear inside a ring?
Optional marks that might also appear inside a ring are the date letter, traditional fineness symbols and the Common Control Mark. The date letter changes every 1 January and was compulsory until 1999. Traditional symbols include a crown for gold, a lion for sterling silver and an orb for platinum. The Common Control Mark, a pair of scales, is recognised across the countries in the International Convention on Hallmarks.
What does a stamp like 10K or 14K mean on a ring?
A stamp such as 10K or 14K on a ring is a maker’s own purity stamp, used mainly in the United States, and not a UK hallmark. It has no sponsor’s mark or Assay Office mark beside it, so nobody independent has tested it. A 10K stamp means about 41.7% gold, a standard the UK does not hallmark as gold at all.
That gap is explained in whether 10K white gold suits an engagement ring. For checks to make before buying, see how to buy wedding rings online.
Frequently asked questions
Why does my ring have no hallmark at all?
Under the UK guidance, rings below set weights are exempt: gold under 1 gram, platinum under 0.5 grams, palladium under 1 gram and silver under 7.78 grams. A ring may also have been made abroad, be plated base metal such as titanium, or have lost its mark when the band was resized.
Does a hallmark prove a diamond is real?
No. A hallmark tests only the metal, never the stones. A 750 mark proves the band is at least 18ct gold, but says nothing about whether the stone is a natural diamond, a lab-grown diamond or a simulant. For the stone you need a grading report, such as one from IGI or GIA.
Can a hallmark wear away over time?
Yes. A hallmark is struck or laser-marked only a fraction of a millimetre deep, so years of daily wear on the inside of the band can soften it. Resizing can also remove it if the jeweller cuts through that part of the band. A worn mark is still valid if it can be read.
Where is the hallmark usually found on a ring?
The hallmark is usually found on the inside of the band, at the back opposite the stone, where the metal is plain. On a band of 2 mm or less the marks are tiny, often under 1 mm tall, so tilt the ring under a bright light and use a magnifier.
Why do some rings show a crown next to the number?
The crown is the traditional symbol for gold in a UK hallmark, struck beside a fineness number such as 375 or 750. It is optional, so many modern rings carry the number alone. A lion shows sterling silver in the same way, and an orb shows platinum.
Is a hallmark from another country valid in the UK?
Yes, if it is a Convention hallmark. Rings carrying the Common Control Mark from a member country of the International Convention on Hallmarks, which the UK joined in 1972, are legally recognised in the UK without re-testing. A maker’s stamp alone, such as 14K, is not.
More guides on this topic
For why gold became the standard band metal, read why wedding rings are made of gold. If you are choosing a new ring, the Solitaire Round Cut Engagement Ring in Platinum and the Solitaire Round Cut Engagement Ring in White Gold show the two classic white metals, or browse all lab-grown diamond engagement rings.
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