What 925 Sterling Silver Actually Is
925 sterling silver is an alloy of 92.5% pure silver and 7.5% of another metal, usually copper — the international sterling standard. The copper is not there for weight; it is there for strength. Pure silver is too soft to hold a form on the hand. The 92.5/7.5 ratio is not a compromise — it is the condition under which silver becomes wearable at all.
Where the number comes from
"925" was not invented by chemists. It is about the weight of a pound, not a percentage. In medieval England a pound of silver was struck into exactly 240 pennies — and that coin-silver pound was called the pound sterling. The mark on a ring is, in effect, the name of an empire's currency: a number that once measured money, not metal.
The percentage came later, when the standard was restated as the decimal fraction of pure silver in the alloy. 925 is 92.5% silver per thousand parts. The figure stamped on a clasp today is older than the stamp itself by several centuries.
Why exactly 92.5
Pure silver is too soft for a ring to live in. At .999 it sits around twenty-six on the Vickers scale — softer than a copper coin, dented by your fingers. A ring of that metal would lose its edge within a week.
So 7.5% copper goes into the silver. After forging, the 925 alloy reaches a hundred and forty to a hundred and fifty — nearly six times harder than pure silver. That is the whole point of the 92.5/7.5 ratio: a jump from twenty-six to a hundred and fifty. The copper does not dilute the silver — it gives it the right to hold a form, an edge and a weight.
The same copper makes the silver responsive. A metal able to darken is a metal that reacts; and reaction is the condition for a surface that lives rather than only shines.
Why it darkens
Silver does not rust. It has nothing to rust with — rust is iron's affair. What darkens on silver does not come from the air as such, but from traces of sulphur in the air and on the skin.
The dark film is sulphide, Ag₂S. Silver takes sulphur from the air and the skin and seals itself under a thin layer. The layer stops on its own once the surface is sealed: beyond that, there is nothing left to darken. This is self-passivation — not corrosion that eats into the metal, but armour that closes it. In darkening, silver protects what lies beneath.
So darkened 925 silver is neither a fake nor a defect. It is a working metal doing exactly what its chemistry allows. Most jewellery is rhodium-plated to block the darkening; STRUGA applies no rhodium and leaves the silver to react — this is Living Silver, the brand's default surface.
What it is — and what it is not
925 silver is a composition: 92.5% silver, the international sterling standard. It should not be confused with a surface. The same 925 alloy can be left bright and uncoated, can be rhodium-plated, can be darkened in advance by oxidation, or can darken on its own on the hand — these are different paths of the same standard, not different metals.
The composition does not depend on geography: 925 is 925 everywhere. And one more boundary, a hard one: 925 silver is a material with character, not a "precious metal" out of the shop-window vocabulary, and not a source of any effect on the person who wears it. The faint unevenness, the tool marks, the uneven surface, the patina and the darkening — these are the character of a living metal, not flaws in the standard.
925 is 92.5% silver, 7.5% copper. The international sterling standard. It darkens from sulphur. One composition — many surfaces.
Questions about 925 silver
Is 925 sterling silver real silver, or fake?
925 is real silver — it is the sterling standard most of the world's silver jewellery is made from: 92.5% pure silver, 7.5% another metal, usually copper. "Pure" silver in a ring would be worse, not better — too soft to hold an edge. A dark film is not fake metal either; it is silver's own chemistry, not a substitute.
Is 925 silver 100% silver?
No. Pure silver is .999, and it is too soft to wear — it dents under your fingers and loses its edge. 925 carries 7.5% copper, and after forging it runs nearly six times harder than pure silver. The copper is not there to cut cost; it is what lets the metal hold a form at all.
Is 925 sterling silver good quality?
925 is the international standard for silver you wear — the alloy chosen because it actually survives daily wear. At STRUGA it is left uncoated: no rhodium plating, so the surface stays alive and reacts. The faint unevenness, the tool marks, the patina — those are the character of a worked metal, not flaws in the standard.
Why does sterling silver 925 turn dark?
It darkens from sulphur — traces of it sit in the air and on skin. The surface grows a thin film of silver sulphide (Ag₂S) that seals the metal and then stops. This is not rust and not wear: silver has nothing to rust with. It stays the same silver under the film. STRUGA leaves it to react — that is Living Silver.