925 is a number stamped on silver, and it carries one piece of information: the proportion of pure silver in the metal. Of every thousand parts of the alloy, 925 are silver. The other 75 parts are something else, usually copper. That is the whole claim. Everything else people read into the stamp — quality, value, craftsmanship — is not in the number.
What the number means
Sterling silver is a recipe stated in parts per thousand. In every 1,000 parts by weight of the finished metal, 925 parts are pure silver and 75 parts are another metal. The name for that proportion is the fineness, and “925” is the fineness of sterling. A piece carrying the number is claiming exactly that: the alloy meets the sterling proportion.
The claim is narrow, and it has been the same for centuries. The number is not a brand, and it is not a grade. Two pieces can both be honest sterling and have almost nothing else in common.
925
parts of pure silver
75
parts of copper, usually
The other 75 parts
The number fixes the silver. It leaves the rest open, and the rest is almost always copper, because of what copper does to the metal.
Pure silver — fine silver, at 999 parts per thousand — is purer than sterling, and too soft for most things that are worn or handled daily. Edges round over, thin sections bend, and a piece slowly loses the shape it was given. Fine silver mostly lives where softness does not matter: in bullion, and in work that will be protected rather than used.
Copper is why sterling holds up. Silver alloyed with copper is harder and tougher than the pure metal, and it keeps the colour and the light that make silver worth wearing. The 75 parts are part of the alloy’s working life, not a dilution of it.
They come at a cost, and the cost should be stated plainly: tarnish. Silver reacts with sulphur compounds in the air and forms a dark film on the surface, and sterling, carrying copper, shows it sooner than fine silver would. But tarnish is a surface, not a rot. It comes off with a polishing cloth, and the metal underneath is unchanged.
Where the marks come from
The number has a history, and it began as consumer protection. In 1300, a statute of Edward I sent the Guardians of the craft from shop to shop in London to assay silver work. No vessel of silver was to leave a goldsmith’s hands until it had been tested, found to meet the sterling standard, and struck with the leopard’s head, the king’s mark. In 1363, each goldsmith’s own maker’s mark was required beside it, so a piece that failed could be traced back to the hand that made it. By 1478 the testing had a permanent home at Goldsmiths’ Hall in London, which is where the word hallmark comes from.
Two protections were built into that system: the metal was tested, and a maker was named. A modern “925” descends from both, and it is worth being clear about how much of them it actually carries on its own.
What the number doesn’t say
- It does not say the silver goes all the way through. Silver-plated ware is a base-metal object wearing a skin of silver, and under Canadian rules the silver in that plating must itself be at least .925 quality for the piece to carry the plated marks. So the number can describe a surface honestly and say nothing about what is underneath. The words that matter are “solid” and “plated,” and a seller should use them plainly.
- It does not grade the work. The number sets a floor for the alloy, not a standard for the making. A thin, clumsy, badly finished piece can be perfectly honest sterling.
- It does not speak for names. “Silver” in a product name is not a fineness. Nickel silver, for instance, contains no silver at all; Canadian marking rules file it under base metals. The silver is in the name, not in the metal.
The number under Canadian rules
In Canada, precious-metal marking sits under the Precious Metals Marking Act, administered by the Competition Bureau. The first thing to know is that marking is voluntary: no maker in this country is required to stamp anything. But the moment a quality is claimed — on the piece, on a tag, or in an advertisement — the claim is regulated. The mark has to be one of the legal ones (“sterling,” “sterling silver,” “.925,” “argent”), it has to be true, and it may not travel alone: applied beside it, by the same method, there must be a Canadian trademark, registered or at least applied for, with proof available if the Bureau asks.
The law allows a tolerance of two parts per thousand — six where solder has been used — because a joined piece is not a laboratory sample. And the claims do get checked. In one inspection campaign, Bureau officers put nearly a thousand pieces of jewellery through X-ray fluorescence analyzers in Vancouver, Toronto, and Montréal, comparing the metal in the tray to the marks on it.
What to ask
Three questions will tell a buyer more than the stamp alone.
- Is it solid sterling, or plated?
- Whose mark stands beside the 925?
- And will the maker state plainly what the alloy is, and stand behind the answer?
Read for what it is — a proportion — the number is exact and useful. Read for more than that, it misleads. The answers to those three questions are what a buyer can rely on.
— Tom