These are the one of the worst possible products to engrave--

--Fiber lasers don't like copper much, especially that which is plating stainless.

--Stainless doesn't like diamond tools, they just barely make a mark and the SS wears them down quick...

I have 3 very similar copper cups I test engraved for a customer. Could barely see the diamond etching, and the fiber would go from a dark brown etch to a bright etch to no etch, all while running the same 1" diameter, very simple logo.

However-! I just drug one out and ran a simple Cermark test, using my 40w LS900, and I got a very nice mark!
It measures about 1/4" tall and 3/8" long-- and I scrubbed it pretty good with a red 'metal' scotchbrite pad and it passed the test!
copper.jpg

I'm surprised actually, but it works! (LMM-6000 Cermark btw)