Sterling Silver

Sterling is a defined recipe: 92.5 percent silver with 7.5 percent copper, which is what the 925 stamp records. Pure silver is too soft to hold a shape, sitting around 2.5 to 3 on the Mohs hardness scale. The copper stiffens it enough for rings, clasps and prongs. Solid all the way through, sterling can be sized, soldered and repolished like gold.

Tarnish is not damage. Silver reacts with traces of sulfur in air, in wool, in rubber bands and in some foods, and the surface builds a dark film of silver sulfide. A treated polishing cloth takes it off in about a minute. Dip solutions work faster but etch the surface slightly and strip deliberate oxidized shadowing out of detailed pieces, so keep them for plain, badly neglected items.

Worn often, sterling largely polishes itself against skin and clothing, so the pieces that go black are the ones sitting in a drawer. What the low price costs you is softness. Sterling scratches and dents more readily than gold, a mirror finish goes satin within months of daily wear, and chlorinated pool or hot tub water attacks the alloy. Take it off before you swim.

Keep sterling in a sealed bag with the air pressed out, because tarnish needs sulfur in air and a closed bag starves the reaction. Against silver tone plating, sterling costs several times more and gives you metal all the way through, so a deep scratch polishes out instead of exposing brass. Weighed against white gold, the upkeep changes shape rather than disappearing. Sterling wants a cloth every few weeks and never a plating bath. White gold wants a bench visit every year or two and no cloth at all.

Silver is refined to 99.9 percent purity, then melted with copper in a fixed ratio to make sterling. The molten alloy is either poured into ingots and rolled into sheet and wire, or cast directly into wax models for shaped pieces. After forming, the piece is pickled in a mild acid to strip the dull oxide that heat creates, then polished.

Some makers finish sterling with a thin rhodium plating to slow tarnish, which changes the maintenance story completely, so it is worth asking. Tarnish resistant variants exist too, using germanium in place of some of the copper to build far less surface film. The 925 stamp is the recipe made visible. In countries with assay offices it sits alongside official hallmarks that certify the fineness independently of the maker.