Hallmark Guide
Understand the small marks that give you independent reassurance about your jewellery’s precious metal purity. Learn what to look for, what the numbers mean and how we help you choose with confidence.
Small marks. Independent reassurance.
Precious metal purity cannot be established by colour or appearance alone. Hallmarking provides an independent check that the metal meets its stated legal standard of fineness.
A hallmark is applied by an Assay Office after testing. The four UK Assay Offices are London, Birmingham, Sheffield and Edinburgh. Their identifying marks are shown here.
How to read a UK hallmark
1. Sponsor’s mark
Identifies the registered person or business that submitted the article for hallmarking. The sponsor can be a maker, retailer, importer or another registered party.
2. Metal and fineness mark
Shows the precious metal content in parts per thousand. The number and its surrounding shape identify the metal and purity standard.
3. Assay Office mark
Identifies the office that tested and hallmarked the article. A date letter and traditional fineness symbol may also appear; these are optional.
Recognise the metal standard
-
375 · 9k gold
37.5% gold
375 parts gold per thousand. This is a recognised UK gold standard. -
750 · 18k gold
75% gold
750 parts gold per thousand. The remaining proportion consists of alloying metals. -
950 · platinum
95% platinum
950 parts platinum per thousand. Platinum purity is expressed by fineness, rather than the gold purity scale.
The legal safeguards
Hallmarking law applies to online sales as well as shops. Most modern articles described as gold, silver, platinum or palladium need a legally recognised hallmark at or above the applicable exemption weight.
The exemption weights are 1 gram for gold, 0.5 gram for platinum, 7.78 grams for silver and 1 gram for palladium. These thresholds concern metal weight, excluding stones. Articles below the relevant threshold and certain other pieces can be legally exempt; mixed-metal articles have additional rules.
UK Assay Office hallmarks and recognised Convention hallmarks provide established routes to compliance. A hallmark verifies precious metal fineness; it does not certify gemstone quality, ethical sourcing or the country of manufacture.
View the official Dealer’s Notice
Confidence in the details
AtelierRings gold and platinum jewellery is hallmarked in accordance with UK requirements. We explain your chosen metal and specifications before you order, with personal guidance whenever you need it.
Our family jewellery heritage dates to Hong Kong in 1959. AtelierRings launched in 2025, bringing that experience to a personal online jewellery service.
Why AtelierRings?
Compare 9k, 18k and platinum
FAQs
Clear answers before you choose. If you would like us to explain the details of a particular piece, please get in touch.
Is a 375 or 750 stamp a complete hallmark?
A number alone is not a complete UK hallmark. Look for the sponsor’s mark, fineness mark and Assay Office mark together. Legally recognised Convention hallmarks have their own formation.
See the official hallmark examples
Does a UK hallmark mean the jewellery was made in the UK?
It identifies the Assay Office that tested and marked the article. It does not establish where the jewellery was manufactured.
Why is there no date letter?
The date letter has been optional since 1999. Its absence does not invalidate an otherwise complete, legally recognised hallmark.
Where can I find the hallmark?
Marks are usually placed discreetly, such as inside a ring’s band or near a clasp. They can be tiny, and a magnifying glass may help. Contact us if you would like help understanding the marking on an AtelierRings piece.
Does a hallmark also certify the diamond?
Hallmarking relates to precious metal purity. Diamond origin, specifications and any individual grading report are separate information.
Learn about our diamonds
Can I ask about hallmarking before I order?
Yes. We can explain the metal specification and hallmarking arrangements for your chosen piece, so you understand the details before deciding.
Speak to AtelierRings
Further reading
Information checked in October 2026 against official hallmarking guidance.
UK Government: hallmarking guidance
The Goldsmiths’ Company Assay Office: understanding hallmarks