This coin has been cleaned as well (although it have way more details) - old copper just don't look like that (it should be like cent coins)
As for the color, saw the picture ... a well cleaned coin with a nice light could give that out - although not for pure copper.
The coins I was referring to are bronze alloy coins - like this one :
http://www.lutecediffusion.fr/piece...59&cid=0&v=1If those pfenig are in pure copper (orange / pink colored) - then that coin has been plated ...