By Rocco Clayfield, Founder & Director, GoldPaid Ltd · Published 6 August 2026
The maths behind 925
Fineness is expressed in parts per thousand. 925 means 925 parts of every 1000 by weight are pure silver, or 92.5 per cent. The balance is almost always copper, although some modern alloys sold as Argentium substitute a little germanium to slow tarnishing.
Silver is not used pure for anything that has to be handled. Fine silver at 999 is soft enough to bend under thumb pressure, so a fork tine would splay and a ring would go oval within weeks. Adding copper hardens the metal enough for daily use. The trade-off is tarnish: copper reacts with sulphur compounds in ordinary air, which is why sterling darkens and fine silver barely does.
Where 925 sits in a UK hallmark
A British hallmark is a row of separately struck punches, not a single stamp. Three parts are compulsory: the sponsor mark (the initials of whoever submitted the piece for assay), the millesimal fineness number, and the assay office mark. The traditional pictorial fineness symbol, a lion passant for sterling in England and a lion rampant on articles assayed at Edinburgh, has been optional since 1999 and is still applied as a matter of course by several offices.
| Punch | What it certifies | Compulsory? |
|---|---|---|
| Sponsor mark | Who submitted the article for assay | Yes |
| 925 in an oval | Sterling fineness, 925 parts per thousand | Yes |
| Assay office mark | Which office tested it: leopard head London, anchor Birmingham, rose Sheffield, castle Edinburgh | Yes |
| Lion passant / lion rampant | Traditional sterling symbol | No, optional since 1999 |
| Date letter | Year of assay | No, optional since 1999 |
Under Schedule 2 of the Hallmarking Act 1973 a UK assay office can mark silver at four standards only: 800, 925, 958.4 and 999. Anything else you see stamped on a piece is a foreign mark, an import fineness, or a manufacturer claim rather than a British assay. The UK silver hallmarks guide sets out the full symbol set.
Why plenty of genuine sterling has no hallmark
This catches people out constantly. UK hallmarking is compulsory only above a weight threshold, and for silver that threshold is 7.78 grams of precious metal in the article. Below it, an item can be sold as silver with no hallmark and no offence committed. For comparison the gold threshold is 1 gram, platinum 0.5 grams and palladium 1 gram.
Many such pieces still carry a plain "925" stamped by the maker. That is a description of the alloy, not a hallmark, because no assay office tested it. It is often correct and occasionally not, which is the whole reason an assay exists.
What 925 is worth in principle
Sterling is paid on recovered silver, and the arithmetic is short. Take the weight of solid silver in the parcel, multiply by 0.925 to get the fine silver content, and apply the market rate for the day, less a margin covering assay, refining and handling. Nothing about the design, the retail price or the sentiment enters that calculation.
Two consequences follow. First, weight dominates far more than it does with gold, because silver is worth a small fraction of gold per gram: a single teaspoon comes to very little while a full canteen of flatware is a serious quantity of metal. Send everything together rather than piece by piece. Second, gross weight is not silver weight. Stones, steel pins and springs, base-metal clasps, enamel, and the pitch or plaster filling in weighted candlestick bases and knife handles are all deducted rather than paid for.
Offers depend on inspection, weight, purity, hallmarks, stones, condition and the market rate on the day. The silver price today page carries indicative dated per-gram figures by standard so you can sanity-check any offer, including ours.
How to check a 925 mark yourself
- Find the marks. On jewellery look inside a ring shank or on the clasp tongue; on flatware look on the back of the stem near the bowl; on hollowware look underneath, near the foot rim.
- Look for a row of separate punches with visible edges, each struck into the metal. A cast or moulded-looking legend that is part of the surface is a manufacturer stamp, not an assay mark.
- Read the fineness. 925 in an oval surround is the UK sterling mark. A walking lion in profile beside it is the optional English sterling symbol.
- Find the office mark. A leopard head, anchor, rose or castle confirms a British assay and tells you where it was tested.
- Check the wear points. Tarnish that polishes off to bright white is normal sterling behaviour. A rub-through on a high edge showing warm copper or pale grey underneath points to plate.
- Do not rely on a magnet. Sterling is not magnetic, and most plated bases are not magnetic either, so a negative result tells you almost nothing.
- If the marks are worn, photograph them and ask before posting anything.
Where a 925 stamp can mislead
A hallmark records what an assay office found at the point of manufacture. It does not certify the piece as it is today. Solder used at joints and repairs is deliberately a lower fineness so it melts below the parent metal, so a heavily repaired item can measure below its mark. Chain and clasp are frequently different alloys on imported jewellery, and a marked sterling clasp fitted to a plated base-metal body is a common combination.
That is the case for testing rather than reading. XRF measures the alloy as it stands now, component by component, in seconds and without scratching, filing or acid. How XRF testing works explains the method and its limits.
What happens to 925 when you post it to us
Parcels are logged on arrival, sorted by standard, XRF-assayed and weighed on calibrated scales. The written offer sets out each item, the purity found, the weight and the rate used, so you can check the arithmetic yourself before deciding anything. Decline it and everything comes back by free tracked return. Accept it and payment is by Faster Payments within one working hour of acceptance, usually within 30 minutes during working hours.
Parcels travel by Royal Mail Special Delivery Guaranteed. Cover may be available up to £2,500 depending on the postal method and cover level used, so heavier lots are often better split across more than one parcel. Named makers, Georgian work and complete original services are flagged in the written offer rather than quietly melted, because those are worth more as objects than as metal. See sell silver by post for the process in full.
Common questions
Is 925 the same as sterling silver?
Yes. Sterling is the name of the standard and 925 is its fineness expressed in parts per thousand, 92.5 per cent pure silver.
Why does my silver chain have no hallmark?
UK hallmarking is compulsory only on silver articles containing more than 7.78 grams of precious metal. Lighter chains, thin rings and small earrings fall below the threshold and are legitimately unmarked.
Is a plain 925 stamp proof of sterling?
No. It is a description applied by the maker rather than an assay office finding. It is usually accurate, but only a test settles it, which is why every parcel is XRF-assayed.
Does tarnish reduce what my sterling is worth?
No. Tarnish is a surface reaction between the copper in the alloy and sulphur in the air. It does not change the silver content and there is no need to polish anything before posting.
Will a magnet tell me whether my silver is real?
Not usefully. Sterling is not magnetic, but neither are most nickel-silver and copper plating bases, so a negative result rules out very little.
Does 925 pay more per gram than 800 silver?
Yes. Sterling holds 92.5 per cent fine silver against 80 per cent for continental 800, so the recovered yield per gram is higher at the same market rate.
What if only the clasp on my necklace is marked?
Each component is assayed separately. A sterling clasp on a plated body is a common combination and the written offer shows what was found on each part.
Is Argentium silver still 925?
Argentium alloys are sold at sterling fineness or above, with germanium replacing some of the copper to slow tarnishing. They are assayed and valued on the fineness found.