METHOD OF PROVIDING MARKINGS TO PRECIOUS STONES INCLUDING GEMSTONES AND DIAMONDS, AND MARKINGS AND MARKED PRECIOUS STONES MARKED ACCORDING TO SUCH A METHOD

摘要

An identifiable mark on a portion of a polished facet of a surface of an article and being identifiable by an optical magnifying viewing device, said identifiable mark comprising a nano-structure formed by a two-dimensional or a three-dimensional lattice of a plurality of discrete nanometer sized recessed or protruded entities, wherein said entities are arranged within a predefined region of said polished facet in a predetermined arrangement in relation to each other and such that an outer interface surface between the facet of the article and air is formed and an inner interface surface between the facet of the article and air is formed. Said predetermined arrangement of said entities is non-uniform and non-periodic arrangement, and wherein said entities are sized and shaped so as to cause optical scattering upon reflection of incident light and the distance from the inner interface surface to the outer interface surface is greater than the amplitude of the non-marked portion of said polished face. Upon reflection of incident light having one or more predetermined wavelengths by said lattice at a predetermined angle of incidence to said lattice, interference due to scattering of light from said lattice is induced such that said reflected light has a variation in intensity providing one or more local maxima of one or more wavelengths. Said mark is identifiable by way of an optical magnifying viewing device inclined at a requisite viewing angle such that a local maxima is detected.