If you have ever squinted at the inside of a ring or the clasp of a necklace and found a tiny 925 stamped into the metal, that number is telling you what the piece is made of. So what does 925 mean on jewellery? It means the metal is 92.5% pure silver, with the remaining 7.5% made up of other metals, almost always copper. That alloy has a name you will recognise: sterling silver.
Why 92.5% and not 100%
Pure silver is soft. Left on its own it bends, scratches and loses shape under everyday wear, which is a problem for something like a ring band. Adding a small amount of copper hardens it considerably while keeping the colour and shine. The 92.5% figure is not arbitrary either: it has been the legal standard for silverware in Britain for centuries, which is where the word sterling comes from.
The other numbers you might see
925 is the most common mark, but it is not the only one.
- 999 is fine silver, 99.9% pure. Softer than sterling, brighter and slightly warmer in tone, and much slower to tarnish.
- 958 is Britannia silver, a higher standard used occasionally for hollowware and some jewellery.
- 800 or 835 indicates lower-purity continental silver, common in older European pieces.
- SP, EPNS or silver plated is not solid silver at all. It is a thin silver layer over a base metal, and it will eventually wear through.
That last distinction matters more than any of the others, and it is worth understanding properly before buying or selling anything second-hand. Our guide to silver plated versus sterling silver covers how to tell them apart.
How to check a mark yourself
Marks are small and usually tucked somewhere inconspicuous: the inner band of a ring, the tongue of a clasp, the back of a pendant bail, the post of an earring. A jeweller's loupe, or even a phone camera at maximum zoom, will normally get you there.
A stamp on its own is not proof, though. Numbers can be faked, and plenty of genuine handmade silver carries no mark at all, because hallmarking is not compulsory everywhere. A few honest cross-checks help. Silver is not magnetic, so a strong magnet that grabs the piece tells you something is wrong. Real silver tarnishes, so an old piece that has never darkened anywhere is worth a second look. And solid silver feels noticeably heavier than plated base metal of the same size.
Where silver clay sits in all this
Jewellery made from silver clay fires down to 99.9% fine silver, so it belongs in the 999 category rather than the 925 one. There is no alloying copper in it: the clay is fine silver powder suspended in an organic binder, and the binder burns away during firing, leaving pure silver behind. The piece also shrinks by around 8-10% in the process, which is simply the empty space between the silver particles closing up.
In practice that means a handmade fine silver piece will tarnish more slowly than a sterling one, but will also be a little softer, which is worth bearing in mind for a ring you intend to wear every day. We go into the trade-off in more detail in our complete guide to silver clay.
Does the number affect value?
Purity sets a floor on what the metal itself is worth, and not a great deal more than that. For most jewellery, the design, the condition, the maker and, for anything sentimental, who gave it to you, matter far more than the difference between 925 and 999. A stamped number tells you what a piece is made of. It does not tell you what it is worth to anyone.
If making your own appeals, our silver clay starter kit contains the clay, a torch, the tools, cubic zirconia stones and instructions to fire a first piece at home. We ship worldwide with import duties covered.
