Does manual toning count? This clown on ebay saturates to the max... Fake Rainbow Toning by Chris Winkler posted Jul 10, 2020 at 9:41 AM
How about this 1966 SMS Kennedy Half Dollar (for those of us who still have retinas after the last post, haha) Same coin, better image. (Felt I could do better.) How about another 1966 SMS:
These have a solid history of turning blue from the original mint bags...but man I still think they're pretty!
I found this 1967 SMS Lincoln Cent in a set where the end (next to the cent slot) had come open. This coin was "trapped" outside its resting place, allowing a more than normal amount of air to enter the set and give it this interesting color.