| 摘要 |
A coin comprises a substrate 20 having one or more coating layers 22,24 of a material or materials different from the substrate 20: a pattern or design is formed using a high power laser to cause localised melting and mixing or alloying of the coating layer and substrate, or of the superposed coating layers. This provides an observable or measurable effect, for establishing the authenticity of the coin. <IMAGE> |
