I was digging through my box of coins collected when I was younger today (looking for something completely different) and ran across two 1954 pennies that have some really nice looking toning. I was wondering if this is really common or something more of a rare occurrence. I'm not great at photographing coins (I tried to just scan them and the looked like plain pennies), but here's my feeble attempt to show what I have on the better looking of the two:



It's more evident on the obverse, especially behind Lincoln, but is there on the reverse as well. Shines like a copper rainbow in the light! Sorry for the poor photos.
Thanks for looking!