| 摘要 |
Coins and tokens manufactured from metal(s), alloy(s) or metal containing material(s). More specifically, they relate to coin structures which enable a coin to be nondestructively authenticated by an ultrasonic measurement. The core part of coin or token includes 2-16 cavities that are not visible from the exterior of the coin or token. Additionally, the core part or coin or token includes at least one part having a different volume microstructure than the rest of the core part. |
