I don't know what they consider to be problem coins when it comes to copper. I know they just slabbed a 2003 Lincoln Cent that's graded MS70. That might be a problem (for a MS70) if a few specks of zinc comes through that drive-by copper wash. 
Copper is not the same with collectors as silver. Copper is unstable and it's expected that there will be things about them that are not acceptable with silver coins but are acceptable with copper. If you want to collect copper coins you just have accept it's nature. Toning, BTW, is in fact corrosion. The coin in your icon is "corroded," but still nice looking.
Copper is not the same with collectors as silver. Copper is unstable and it's expected that there will be things about them that are not acceptable with silver coins but are acceptable with copper. If you want to collect copper coins you just have accept it's nature. Toning, BTW, is in fact corrosion. The coin in your icon is "corroded," but still nice looking.


















