Abstract: The present invention provides for a security article for anti-counterfeit (21, 31), authentication and/or tracking purposes, comprising a substrate material (25, 32) including at least one, but preferably several encoded metal holographic platelets, wherein each platelet (22, 33) carries a surface relief diffractive structure and can be authenticated by inspection of both a holo-graphic device by illumination and visual, eyeglass and magnifier inspection and which can also be authenticated by inspection under magnification of an aperture in the metal platelet carrying an authenticating code.