Aside from safety, I think this is my biggest concern with precious metals. If worn daily, surely will scratch and get dull. Polishing is an option, but for a very limited number of times before it detriments the coating. Do brand service centers reapply gold onto cases during servicing? Is this a thing?
On a side note, it seems Rolex Everose contains some amount of platinum, which helps it hold its copper so as to retain that soft reddish tone for much longer. A plus point for rollies. ALS also has a proprietary blend they call honey gold, which they claim to be much harder than platinum. Which is interesting - the hardness of platinum comes up to about 230 Vickers, and the hardness of strong stainless steel formulations can come up to 390 Vickers. This honey gold must be some serious stuff.