Test the metal.
Keep the piece.
Traditional acid and fire-assay testing damages the very item you're trying to value — a scratch on a ring, a nick on a bar, a melted corner of a coin. X-ray fluorescence (XRF) reads the metal's elemental fingerprint without touching it.
A focused X-ray beam excites the sample's atoms; as electrons fall back into place, each element emits a characteristic energy signature — gold's is distinct from silver's, which is distinct from copper's. An Amptek (USA) silicon drift detector captures that signature, and the analyzer's software reports composition and purity directly on screen.
It's the same principle used in jewelry stores, refineries, pawnshops and quality-control labs worldwide — this page is a draft showcase of three benchtop models built around it: the EDX-B3, EDX-B6 and EDX-B9.