Published 2 June 2026
What a hallmark is for
A hallmark is the oldest form of consumer protection in Britain. The Worshipful Company of Goldsmiths was given the right to test and mark precious metal items in London in 1300. The system that followed grew across the kingdom and is now governed by the Hallmarking Act 1973. The marks tell you that an independent assay office tested the metal and confirmed it meets the standard claimed.
Without the assay office mark, a stamped "750" on a chain is a manufacturer's assertion, not a legal certification.
The three compulsory marks
1) Sponsor mark. This is the maker, importer or sponsor of the piece. It is a unique punch registered with one of the assay offices. Usually two or three initials inside a shield or shaped cartouche.
2) Standard mark. The three-digit number that shows the parts per thousand of precious metal in the alloy. 375, 585, 750, 916 and 999 for gold. 800, 925, 958, 999 for silver. 850, 900, 950, 999 for platinum. 999 also appears for palladium.
3) Assay office mark. The town mark of the office that tested the piece. The four UK offices are London (leopard's head), Birmingham (anchor), Sheffield (Tudor rose, formerly a crown until 1975), and Edinburgh (three-towered castle).
The optional fourth and fifth marks
Traditional pictorial mark. The crown for 22ct gold, the lion passant for sterling silver (when the silver is also struck with a traditional fineness mark), Britannia for Britannia silver. These are pictorial and have been used continuously for centuries.
Weight thresholds you should know
The 1973 Act sets minimum weights below which an item is not legally required to be hallmarked. Gold below 1 gram, silver below 7.78 grams and platinum below 0.5 gram fall outside compulsory hallmarking. That is why tiny stud earrings, infant signet rings and thin charms may genuinely be solid gold but carry no assay office mark. The XRF report fills that gap.
A piece sold as precious metal that is above the threshold and is not hallmarked is either pre-1973 imported stock, a foreign piece that has not been re-assayed for sale in the UK, or not actually the metal claimed.
Where to look on the piece
- Rings: inside the shank, near the bottom (the point of the ring opposite the stone). On heavy bands, on the inside surface where it sits against the finger.
- Chains: on the bolt-ring or lobster clasp, and sometimes on a small tag soldered next to the clasp.
- Earrings: on the post just below the back, or on the back of a stud.
- Pendants: on the bail (the loop at the top), or on the back face.
- Bracelets: on the clasp, or on the bar of the figure-of-eight safety catch.
- Pocket watches: inside the case-back, often with a separate sponsor mark for the case maker.
Common stamps that are not full UK hallmarks
"K", "Kt" or "KT" written after a number is a karat designation often used on US-imported pieces. "750" alone with no assay mark is a foreign or unhallmarked claim. "GF", "GP", "GEP", "RGP" and "HGE" are plating or rolled-gold abbreviations and not full standard marks. A complete UK hallmark always has three punches: sponsor, standard, assay office.
What a postal buyer does with the hallmark
A hallmark is the starting point of the valuation. The XRF test is then used to confirm the alloy still matches the stamped standard. Mismatches happen, usually because a chain has been repaired with a different-karat solder, or because a counterfeit stamp has been applied to a base-metal piece. The XRF result is what the offer is paid against. If the metal does not match the stamp, the offer is calculated honestly against the metal that is actually there.
Your parcel is insured up to £2,500 via Royal Mail Special Delivery. Final offers depend on inspection, item weight, purity, hallmarks, stones, non-gold components, condition and the live precious-metal market. See the full sell gold by post method.
A practical close
You can do a lot with a 10x loupe, a kitchen scale and 10 minutes. Read the standard mark, locate the assay office mark, find the sponsor and date letter if present. The remainder is the metallurgy, which is what the XRF report exists for. Once you have both, you are negotiating with information, not guesswork.
Common questions
Is a "925" stamp on its own a UK hallmark?
No. It is the standard mark for sterling silver. A full UK hallmark would include a sponsor mark and an assay office mark beside it.
My ring has only "18K" stamped inside. Is it real?
It is a karat claim, not a UK hallmark. It may still be solid 18ct gold, but it has not been independently assayed for the UK market. XRF will confirm.
Why is the date letter so confusing?
Each assay office cycles letters with a changed shield shape every 20 to 26 years. The same letter in two different shields can be 60 years apart. A reference chart is needed.
Are foreign hallmarks accepted in the UK?
Convention hallmarks struck under the international Vienna Convention are recognised by UK assay offices. Other foreign marks usually are not.
Is a hallmark a guarantee against forgery?
The marks themselves are protected by law. Counterfeit punches do exist. XRF testing is the modern check on whether the metal under a stamp matches the stamp.
Does GoldPaid pay on hallmark alone?
No. The hallmark is the starting point. The XRF test is the confirmation. The offer is paid on the tested metal content.
Where is the assay office mark on my ring?
Usually grouped with the standard mark and sponsor mark on the inside of the shank.
Do unhallmarked old pieces lose value?
Only as a question of trust. If XRF confirms the metal, the recovered yield is the same as an identical hallmarked piece.