Banknotes as a medium of exchange for goods and services have been used throughout the world for the last two hundred years. During this time banknotes have been refined to provide ever increasing security against counterfeiting. Enhancements such as special substrates, Intaglio printing, planchets, watermarks, portraits, colored fibers, and guilloche patterns have been employed. More recently, holograms, laser perforation, optically variable devices, and security threads have been added to the banknotes as further deterrents as counterfeiters have become more adapt at using new technologies to simulate the older features. Some examples of these anti-counterfeit features are discussed as well as some counterfeit notes. New technologies are being created that are just now being introduced to the banknote community. These include combination optical devices such as Chromagrams~R, oriented optically variable devices, de-metallized optically variable threads and virtual image devices. These devices are shown and described.
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