Settings to engrave gold plated stainless steel with 20W fibre laser omtech

I have an omtech 20W fibre laser engraver and using lightburn. I’m trying to understand what settings (power, frequency, speed) I would need to use in order to correctly engrave 18k gold plated stainless steel. How do I alter the depth of engraving? How do I make the engraver colour lighter, not black. Any help on settings would be greatly appreciated as I’m lost!