A process of forming a non-optically detectable authentication marking (210,320, 410,535) in a diamond (200,300). Authentication marking (210,320,410,535) is formed adjacent the outer surface of an article formed from a diamond material having intrinsic optical centers. Method includes the step of applying an image ...

A process of forming a non-optically detectable authentication marking (110), includes the step of: applying a marking at a surface of a diamond (200) using a focused ion beam (FIB) writing process so as to provide a non-optically detectable authentication marking (110) which is formed by alteration in the optical c...

A method of forming a non-optically detectable identifiable marking invisible to the naked eye, said marking is formed from a of plurality of recesses of multiple levels at an outer surface of an article formed from a solid-state material, and said method including the steps of: forming a plurality of recesses of mu...