Sterling vs Fine Silver: Tarnish, Wear and Price

Silver has no karat system, only a fineness number. The two you will meet are 925 and 999, and the trade is simple: 999 is purer, softer and slower to discolour; 925 gives up 7.5% of that purity to buy hardness.

The 7.5% that buys all the hardness

999 fine silver is 99.9% silver with almost nothing else; 925 sterling is 92.5% silver and 7.5% copper. That copper is not filler — it wedges into silver’s crystal lattice and disrupts it, which is what lets sterling hold cast detail and prong settings. Quoted hardness sits in different bands: fine silver around 25 to 35 Vickers, sterling roughly 65 to 100 depending on how it was formed. Wear resistance follows hardness. Purity barely moves cost: a gram of 999 holds about 8% more silver than a gram of 925.

	Silver content	Hardness	Tarnish	Sensible use
999 fine	99.9%	around 25–35 Hv	slower	chains, earrings, pendants
925 sterling	92.5%	roughly 65–100 Hv	faster	rings, bracelets, prongs

Where soft silver is fine, and where it is not

Load decides. A ring shank takes continuous pressure and grinds against desks and doors, so soft metal deforms. A chain link mostly hangs — the load runs along the wire and abrasion is light. Ear studs carry almost no bending force. Pieces under the least mechanical stress tolerate the softest metal, which is why fine silver appears in chains, studs and pendants rather than everyday rings.

Tarnish is sulphur, not air

The film is silver sulphide, formed when surface silver meets hydrogen sulphide and other sulphur compounds. Humidity is the accelerant, not oxygen: moisture lets the reaction run, which is why a bathroom drawer ruins silver faster than a dry cupboard. Accelerants worth knowing: rubber bands and latex, wool and felt, wood and wood-pulp products, newsprint, cosmetics, chlorinated water and skin chemistry. On sterling the copper reacts too.

Rhodium is a shield with a deadline

Rhodium, a platinum-group metal, is inert to atmospheric sulphur, so many sterling pieces are electroplated with a thin layer for a bright finish and tarnish protection. The layer is not permanent. On high-friction areas — inside a ring shank, along bracelet links — it commonly wears away within a year or two, and the silver underneath behaves normally. Re-plating is a jeweller’s job. Where a listing calls a silver piece white gold, that layer has to be declared. 16 CFR 23.7 makes it deceptive to leave a rhodium surface layer undisclosed on a product marked or described as precious metal. Sterling sold as sterling is described as a precious metal, so a rhodium-plated piece has to say so; costume jewellery advertised without any precious-metal claim sits outside the rule.

Telling them apart in the shop

Look for the stamp first: 925, S925 or Sterling for the alloy, 999 or Fine Silver for the pure metal. A stamp is not proof, but its absence on a piece sold as silver is a warning. A magnet only rules out ferrous base metals, and cannot separate 925 from 999 or either from brass. The definitive non-destructive check is XRF, which many jewellers have and which takes seconds. Storage decides how often you polish, and vermeil is the same question with gold on top.