I agree paint or red ink the green spots are copper comming from the coin....I bet my bottom dollar it was dipped in paint or ink...I never have seen tonning as such and I been collectin nickels since 1962. I have seen different reactions from chemicals most are pitted or lost of details this coin seems to have most of its high points still in tack....that clues me to believe what ever the dip was protected the high surfaces from wear... but the stars would of wore off first being the highest point on this coin.