Hologram is very difficult to copy. Generally what passes as copies of holograms are not holograms at all, but diffractive material with screen printing and or hot stamping with various foils. To the untrained eye they appear like holograms because they have some form of rainbow colours. They are crude pass offs that do not stand any scrutiny and cannot be called holograms. Holograms cannot be copied by any known printing technique. All printing is done with ink whereas hologram is an inkless optical process that cannot be scanned, photocopied, or electronically transmitted. A properly specified and executed hologram is impossible to duplicate. Every hologram has a signature and it is not possible to replicate it well that is why holograms are used on over 90 currencies around the world such Pound Sterling, Euro, Japanese Yen, Swiss Frank, etc.