After 6 months the coating on my Bronze mini is wearing ever so slightly around the tear drops. I do work in a factory, and often have chemicals on my hands used in the manufacturing process. As much as I do try to wash my hands, some of that stuff just lingers. You have to look closely to see it, and my husband advises to just not look at it.
I have a black mini on the way, which I will not take to work. It will be interesting to see what happens when I don't take that one around chemicals.
Really, the whole thing does not bother me that much because I always have the option of a JWrap.