Lasers mark the substrate using the concentrated energy of the laser beam, which is focused to a microscopic spot that moves across the area to be marked. The actual mark is achieved by a colour contrast between the base substrate and the area that has been marked.

Marking is by a number of methods:

- ablation or removal of the surface coating to expose a base material in a contrasting colour

- annealing, which produces a legible, dark mark on the surface without removing any material

- engraving that vaporizes substrate material to produce a mark

- chemical reaction where the substrate is melted, foamed or bleached, producing a mark that depends on the composition and colour of the base material.