How to Tell Real S925 Sterling Silver from Silver-Plated Brass

Sterling silver is legally defined as 92.5% pure silver alloyed with copper for strength. Everything below — from stamps to lab reports — exists to answer one question: is the piece solid sterling, or plated brass that will show through in weeks?

Start with the hallmark

Solid sterling is almost always stamped: 925, S925, Sterling, or Sterling Silver. The stamp is necessary but not sufficient — it can be struck into plated brass as easily as into silver. Treat the hallmark as a lead, not proof.

Quick field checks

Magnet test. Sterling silver is not magnetic. If a piece sticks to a magnet, it is either plated base metal or contains steel parts. Note the caveat below before condemning a whole lot.
Weight and density. Sterling sits at 10.3–10.4 g/cm³; brass is 8.4–8.7. Solid pieces feel noticeably heavier in hand than same-size plated ones.
Sound and flex. Sterling rings with a clear, sustained tone when tapped and resists bending; plated brass thuds and flexes.
Oxidation behavior. Sterling tarnishes evenly and polishes back to bright. Plating flakes at edges and high points first.

Where the magnet test lies

Ear wires, clip springs, post backs and pin hinges are sometimes steel or other alloys by design — a tiny steel spring in a clip mechanism does not make the piece fake. Judge the body of the piece, not its moving parts.

The acid test — carefully

A silver testing solution (schröter’s reagent) on a hidden spot tells you quickly: sterling reacts with a creamy red color, brass with green. Use it on the back of a finding or an inconspicuous edge, and warn your supplier first — a drop leaves a mark.

Density check for a whole lot

For volume orders, weigh a sample piece and measure displacement in water: density = dry weight ÷ (dry − wet weight). A consistent reading around 10.3 g/cm³ across several pieces is strong evidence of solid sterling throughout the lot.

The paperwork that actually proves it

Physical tests screen; documents prove. For any serious wholesale order, ask for:

A test report from an accredited lab covering the lot or style (the monitoring report form number should be traceable).
Per-lot weights matching the style sheet — solid silver can’t be faked at the weighing stage without the numbers drifting.
The material declaration on your quotation, so the stated S925 becomes a contract term rather than a marketing word.

Price is a test too

Silver trades on a public spot rate. If a quoted price implies less silver than the piece weighs, someone is paying the difference — and it won’t be the factory. Reputable sellers quote metal plus fixed processing fee, indexed to the spot rate on the order day. That’s the structure we use, and it’s the one we recommend demanding from any supplier.

Bottom line for buyers

Hallmark first, magnet and weight as screens, density on a sample, and lab paperwork on the contract. Four layers deep, plated brass doesn’t survive — and neither does a bad supplier.