Definition

• Procedure for distinguishing a struck coin from an electrotype or cast copy; or for telling if two coins of the same kind are of the same metal. Balance the coin on a fingerti and gently tap it on the rim with another coin. A struck coin will produce a prolonged tone; anything else, a brief "tink" or a dull thud. (Exceptions: A struck coin on a dumb blank or with a planchet crack will ring briefly or not at all; a coin unusually thick for its diameter will ring more briefly than a thinner one of the same metal and diameter.) Two coins of the same diameter, thickness, and alloy will produce the same note; small changes in alloy produce large changes in pitch of the note. The text, while not necessarily conclusive of genuineness in itself, has heuristic value: After hearing a dull thud, one scrutinizes the edge for for the seam characterizing electrotypes, and other areas for porosity, bubble marks, stem spot, or other evidence of casting.

Source

• Breen Encyclopedia

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