While the oxide is much harder all it would take is for the user to put it in their pocket with coins or keys.
My answer is that if the owner is one that can't accept wear then you don't want them as a client or buyer.
Does any of you who have a Xiaomi phone with aluminium back and carry it without a case have any scratches on it from everyday use? I don't if the color will scratch of from everyday use. I have a Redmi 5 Plus 4Gb/64Gb in Blue.
Thanks in advance