The present invention relates to a method of forming an optical element that includes a mark. The method involves, irradiating at least a portion of a surface of the optical element with laser radiation, thereby forming a plurality of substantially parallel elongated grooves in the portion of the surface, which are each aligned substantially parallel with a common longitudinal direction that extends from a center point of the plurality of elongated grooves. The plurality of elongated grooves together define the mark. A clear film is formed over at least the portion of the surface and the plurality of elongated grooves. Depending on the orientation of a source of electromagnetic radiation as viewed through the optical element relative to the common longitudinal direction of the grooves, the mark is either observable or unobservable. The present invention also relates to an optical element having a mark, as described above.