METALS
We can get the same fine, detailed engraving on stainless steel items with the use of a metal marking compound. This is a chemical that is painted on the surface that chemically reacts to the metal surface where the laser hits. The result is a dark gray matt area that contrasts nicely with the light shiny surface of the steel.
If the stainless steel is coated, as in colored travel mugs, we can often laser the coating off to reveal the shiny metal underneath.