Black metal engagement rings

Are there any new developments with black coatings on gold engagement rings? I’m revisiting this subject because it’s been awhile and a retail jeweler was quite unhappy that I was unwilling make one. My argument was that anything that makes gold, platinum or palladium black is a coating that will wear off, when it does I will be responsible for redoing the coating. The customer had a silver ring that was oxidized totally black, which was noticeably wearing off, and she wanted a blackened 14K gold one with diamonds made like it. His argument was that you see so many on the market that the metal is either black (I say no) or the coating lasts, even with daily wear (again, I say nope).

I’m just checking in to see if there is something new out there and I might be wrong…that happens with some frequency. Thanks