A mold for imparting a marking including a requisite optical element has two and a half dimensions (2.5D) to the outer surface of an article formed from a ductile material. The mold includes a marking surface for imparting the mark to an outer surface of the article. That imparting is done by localized plastic deformation of the material from which the article is formed upon the mold and the article being urged against each other. The marking surface includes a micro-structure formed by an arrangement plural micro meter sized recessed or protruded entities. The entities are arranged in a predetermined arrangement in relation to each other, and the entities are arranged as a micro-structure having two and a half dimensions (2.5D). The entities are arranged in an inverse arrangement compared to the optical element, and to provide the recesses extending from the marking surface into the mold.