Sterling silver versus silver plated versus stainless steel

Three pieces can look identical in a photograph and behave completely differently on a neck. One is solid alloy all the way through. One is a thin skin of silver over something cheaper. One is not silver at all and never pretended to be. The differences show up in how the piece tarnishes, how heavy it feels, and whether it still looks like itself after a year. Here is how to read the labels, and what to do when there is no label.

What 925 means, and what it does not

Sterling silver is 92.5 per cent silver by weight. The remaining 7.5 per cent is usually copper, sometimes with zinc or germanium. That is the whole of it: 925 parts per thousand, which is why the stamp reads 925. Pure silver, stamped 999 and sold as fine silver, is too soft to hold a clasp or a claw, so almost nothing wearable is made from it.

The copper is what does the damage and the work at the same time. It makes the alloy hard enough to be useful, and it is also the part that discolours fastest and most unevenly. An alloy with germanium replacing some of the copper, sold under the Argentium name, tarnishes noticeably more slowly, costs more, and is rare in anything inexpensive.

A 925 stamp is a fineness mark, not a guarantee of anything else. It tells you nothing about the quality of the soldering, the thickness of the chain, or whether the clasp will outlast the pendant. It is also easy to stamp on something that is not sterling, which is why a stamp on an unknown piece is a claim rather than proof. In the UK, pieces containing more than 7.78 grams of silver legally require a full hallmark including an assay office mark, which is a much harder thing to fake than three digits. Most earrings and small pendants fall under that weight and are exempt, so the absence of a hallmark on a light piece means nothing either way.

Silver plated means a surface, measured in microns

Plated jewellery is base metal, usually brass, copper, a zinc alloy or a nickel alloy, with silver deposited on the outside in a layer measured in microns. A thousandth of a millimetre is a micron. Good plating might be 2 to 5 microns thick. Flash plating, which is what you get at the bottom of the market, can be under half a micron, which is less than the depth of a fingernail scratch.

This matters because plating does not fade, it wears through. The piece looks correct until the day the base metal appears at an edge, a ring shoulder or the back of a pendant where it rubs against clothing, and from then on it looks wrong in a way that cannot be polished out. Replating is possible and usually costs more than the piece did.

Watch the wording. Sterling silver plated means base metal with sterling on the outside. Silver tone and silver finish mean no silver at all. Nickel silver, German silver and alpaca silver are all copper, nickel and zinc, with no silver in them by any amount.

Stainless steel is a different proposition entirely

Stainless steel is iron with at least about 10.5 per cent chromium, which forms a thin passive oxide film that repairs itself when scratched. That film is why it does not rust and does not tarnish. The two grades you see in jewellery are 304, often labelled 18/8, and 316L, often sold as surgical steel, which contains molybdenum and resists salt and sweat better.

Steel is harder than silver, so it keeps a polish and resists scratching in a way silver never will. It is also harder to work, which is why steel pieces tend to be simpler in form. You rarely see fine filigree or deep undercut detail in steel, because the tooling cost does not justify it.

The trade off is that steel cannot be oxidised the way silver can. A black steel piece is coated, usually with a physical vapour deposited layer, and that coating wears like any other coating. A blackened silver piece is discoloured silver, which is a different thing and behaves differently. Both grades of stainless above contain nickel bound into the alloy, which matters to some people and is covered in our piece on earring posts and sensitive ears.

Tarnish is evidence, not a fault

Silver tarnish is silver sulfide. It forms when sulfur compounds in ordinary household air reach the surface, and humidity speeds it up. It is not caused by the piece being cheap or badly made. It is caused by the piece being silver.

So tarnish is a useful signal. A piece sold as silver that has sat in a drawer for a year and come out exactly as bright as it went in is either coated, rhodium plated, lacquered, or not silver. The reverse test is less reliable: plated pieces can also tarnish, because the base metal underneath discolours once the plating is thin, and copper and brass go their own colours as they do it.

Pieces that are meant to be dark, like The Skull and the Wing or The Moth Ring, use the same chemistry on purpose. The surface is deliberately darkened so that recessed detail reads and high points catch the light. Treating that as tarnish and attacking it with a polishing cloth is the single most common way people ruin an antiqued piece.

Three tests you can do at home

Weight for size is the most useful. Silver has a density of about 10.5 grams per cubic centimetre. Brass is about 8.5 and stainless steel is about 8. A solid silver piece feels heavier than it looks, and once you have held a few you can feel the difference between silver and a hollow plated shell without thinking about it.

A magnet tells you about the core. Silver is not attracted to a magnet at all. Neither are the common austenitic stainless grades, or not strongly. If a fridge magnet grabs a piece firmly, there is ferrous metal in it, and that rules out solid silver.

Look at the wear points under a phone camera at full zoom: the inside of a ring, the back of a bale, the edge of an ear wire. Plating gives itself away at an edge before it gives itself away anywhere else. A faint warm line of yellow or pink where the surface has rubbed is brass or copper showing through.

What we will and will not tell you about our own stock

We do not publish a material on a product page unless the supplier's own documentation gives us the figure. That means some pages are more specific than others, which is less satisfying than a confident claim and more honest than inventing one.

If you want to know what a particular piece is made from before you buy it, email us and we will go and read the spec for that piece rather than quoting a general rule. That applies to the chain as much as the pendant, because the two are often made by different factories and the chain is usually the part that fails.

If you are buying for somebody who reacts to metals, the material question is the whole question, and a general answer is not good enough. Ask us about the specific piece. We would rather lose a sale than guess on your behalf.

Questions people actually ask

Does 925 mean real silver?

The 925 stamp means 92.5 per cent silver, which is the sterling standard. It is a fineness mark rather than proof of authenticity, because a stamp can be applied to anything. On a heavier piece, a full set of hallmarks including an assay office mark is much stronger evidence than the three digits alone.

Is stainless steel better than sterling silver for jewellery?

It is more durable and it does not tarnish, because chromium forms a self repairing oxide film. Silver is softer, takes finer detail, and can be deliberately darkened in a way steel cannot. Neither is better in general: steel wins on toughness, silver wins on detail and on being repairable.

Why has my silver plated necklace changed colour?

Either the base metal underneath has started to show through where the plating has worn thin, or it is discolouring through a plating layer that was always very thin. Wear through shows first at edges and rubbing points, and it usually appears as a warm yellow or pink line rather than grey or black.