Materials
925 sterling silver explained: the stamp, the tarnish and the fakes
Three digits that mean 92.5% silver. They also mean the piece will darken, and that the stamp alone proves very little.
Zayr Studio4 min read
Updated
925 means the metal is 92.5% pure silver by weight, with the remaining 7.5% usually copper. That alloy is called sterling silver: pure silver is too soft for most jewellery, and the copper makes it strong enough to hold a shape and a stone. Sterling tarnishes over time as the silver reacts with sulphur in the air, and a 925 stamp on its own does not prove a piece is genuine.
Why 92.5% and not pure silver
Fine silver, stamped 999, is 99.9% silver. It is beautiful and very soft: a fine silver ring would bend out of round and scratch within weeks of daily wear. Adding copper makes the metal harder and more durable without changing its colour much, and 92.5% has been the standard compromise for centuries.
| Stamp | Silver content | What it is | Notes |
|---|---|---|---|
| 999 | 99.9% | Fine silver | Very soft; bullion, some traditional pieces |
| 958 | 95.8% | Britannia silver | Softer than sterling; less common |
| 925 | 92.5% | Sterling silver | The jewellery standard |
| 900 / 800 | 90% / 80% | Coin silver and lower standards | Harder, slightly more prone to tarnish |
| EPNS, “silver plated” | Surface only | Silver plating over base metal | Not solid silver |
| “German silver”, nickel silver | None | Copper, nickel and zinc alloy | Contains no silver at all |
The chemistry of tarnish
Silver tarnish is not rust and, despite common belief, it is not mainly caused by oxygen. It is silver reacting with sulphur compounds in the air, chiefly hydrogen sulphide, to form a thin layer of silver sulphide. That layer starts as a faint yellow, deepens to brown and eventually turns black.
The copper in sterling can also oxidise, which is part of why sterling tarnishes a little faster than fine silver. The process is surface-only: tarnish sits on the metal and does not eat into it, which is why a black, neglected silver piece can usually be brought back.
What speeds tarnish up
- Humidity. Moist air speeds the reaction, which is why silver darkens noticeably faster during Lahore and Karachi monsoons.
- Sweat, lotions, hair products and perfume on the skin.
- Sulphur-containing materials: rubber bands, wool, felt, some cardboard and papers.
- Foods such as eggs, onions and mayonnaise, if handled while wearing silver.
- Air pollution, particularly near traffic and industry.
- Storage in the open air rather than in a closed pouch or box.
What slows it down
- Wearing it. Gentle friction against skin and fabric keeps regularly worn silver brighter than silver left in a drawer.
- Storing each piece in a sealed zip bag or anti-tarnish pouch, with the air pressed out.
- A sachet of silica gel in the jewellery box during the monsoon.
- Putting silver on after perfume and cream, not before.
- Wiping pieces with a soft silver cloth after wearing.
Removing tarnish once it has formed depends on how heavy it is and whether stones are involved, and it is covered step by step in the guide to removing tarnish.
Oxidised silver is tarnish on purpose
“Oxidised silver” is silver that has been deliberately darkened, usually with a sulphur solution, so that recesses in the design turn dark and raised areas are polished back to bright. It is the look of much traditional and tribal-style jewellery. The name is technically inaccurate — the dark layer is a sulphide, not an oxide — but it is universal.
Treat oxidised silver differently from bright silver: do not dip it in silver cleaner or use a foil-and-baking-soda bath, which will strip the darkening from the recesses along with the dirt. A soft dry cloth on the raised areas is all it needs.
Rhodium-plated silver
A lot of modern sterling silver jewellery is plated with rhodium, which gives a brighter, whiter finish and stops the silver underneath from tarnishing while the plating is intact. It is a good option in a humid climate, with one caveat: the plating wears over time, most quickly on rings.
How to tell real sterling from fakes
A stamp is only letters pressed into metal. Anyone with a punch can stamp 925 on brass. Pakistan does not have a single mandatory national hallmarking system for silver in the way some countries do, so the stamp is a claim rather than an independent guarantee. These are the checks that actually help:
- Magnet: silver is not magnetic. If a magnet sticks strongly, it is not solid silver. If it does not stick, that proves nothing, because brass, copper and nickel silver are not magnetic either.
- Tarnish behaviour: real sterling darkens gradually to grey-black. Green or brassy colour showing through at worn edges suggests plating over copper or brass.
- Weight: silver is dense. A chunky piece that feels surprisingly light may be hollow or a lighter base metal.
- The acid test: a jeweller or sarafa can apply a silver testing acid to a hidden spot. Real silver reacts with a characteristic colour.
- XRF testing: some gold and silver testing services use an XRF machine, which reads metal content without damaging the piece.
Silver is priced by weight against the daily silver rate, with making charges added, so check the day’s rate with your local jeweller rather than relying on a figure you saw online. For rings specifically, silver is compared with rhodium-plated and steel options in the silver rings guide.
Zayr does not sell sterling silver. The women’s rings are rhodium- or gold-plated over a hypoallergenic base, and the men’s pieces are 316L steel; both are listed as exactly that.
Real silver tarnishes. That is not a defect; it is one of the more reliable signs you are looking at the real thing.
Common questions
What does 925 mean on jewellery?
It means the metal is 92.5% pure silver by weight, known as sterling silver. The remaining 7.5% is usually copper, added to make the silver hard enough for jewellery. The stamp is a claim by the maker, not an independent test.
Does 925 sterling silver tarnish?
Yes. Silver reacts with sulphur compounds in the air to form a dark silver sulphide layer, and humidity, sweat and perfume speed it up. Storing pieces in sealed bags, adding silica gel in the monsoon and wearing them regularly all slow it down.
Is German silver real silver?
No. German silver, also called nickel silver, is an alloy of copper, nickel and zinc and contains no silver. It is silver in colour only. It also contains nickel, which matters if your skin is sensitive to it.
How can I check if my silver is real at home?
Home tests can only rule things out. If a magnet sticks strongly, it is not solid silver, and brassy colour at worn edges suggests plating. For a real answer, ask a jeweller to do an acid test or use an XRF testing service.
What is oxidised silver?
Silver deliberately darkened, usually with a sulphur solution, so the recesses of a design are black and the raised parts bright. Do not clean it with silver dip or baking soda baths, which strip the darkening. Wipe it with a soft dry cloth instead.
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