Try drag engraving, next to impossible to break a cutter.



Circle is 50mm diameter, small letters near the bottom are 1/2 a mm

Laser will only engrave alloy if it's been anodised and the letters are always white, so just using anodised alloy looks a bit like an Italian flag, white cross on white background.

You need a colour that compliments it like red, blue or black.



If you want it the opposite way, black letters on alloy then you need a product called Thermark which is a ceramic slurry made from 3rd dynasty Chinese Ming vases as it's £100 an aerosol [ no typo ] but does last a long while