Ring Test. Tapping a suspended coin or medal on the edge for its resonance. The ring of any small metal object is due to its internal structure; thus its alloy, thickness and any gas pockets affects its tone. Both cast and struck items will ring but with notes of different pitch (it is necessary to compare a suspect item with a known or genuine item). Using a ring test for authentication, however, is delusive.A ring test could detect a cast copy, for example, but could not differentiate a struck copy from an original. It could detect different metal compositions but not minute differences of alloy. The sounds of the ring test could range from a high prolonged tone (from a large thin piece) to a dull thud (from a thick base metal cast). A dumb blank would fail a ring test by such a dull thud, as well as coins with a lamination error will fail the ring test.A ring test is critical for gold coins. Concerned mints have employed testers to bounce freshly struck gold coins on a metal drum to check if they ring true. Dumb blank coins would be rejected and melted. The Philadelphia Mint did this, for example, until early 1930s.
excerpted with permission from
For Artists, Makers, Collectors and Curators
COMPILED AND WRITTEN BY D. WAYNE JOHNSON
Roger W. Burdette, Editor