It's a little unusual but not rare. No doubt it's something about the storage conditions.
I have one nickel that is turning rainbow on the reverse wish it were the obverse. As for storage they have never been opened yet were stored in un-airconditioned bedroom in Arizona's heat for 40+ years. As to cleaning they are still sealed and I'm probably selling them so I'll let the new owner worry about that. Funny How all the sets were stored in same box yet early 70s were not toning and 78 on not toning either just 75,76 and part of 77.
Edited by Roagan
09/17/2021 1:18 pm
09/17/2021 1:18 pm



















