I'm just found this 50c franklin perf 11 (#517). The color seems to me like the 20c Franklin. Do anybody think this could be a color error? Or maybe it just a oxidation? I welcome all opinions. Thanks if can give me some information.
I've seen a lot of orange to brown & green to blue change. Now I found a purple to blue . Too bad it's not orange. That would be more interesting. I like the detailed information on stampsmarter. I never seen before. Thanks Don