looks stained to me ... but what do I know @paddyman98 Read this ==> https://www.cointalk.com/threads/19...is-a-improperly-annealed.323135/#post-3183442
Wait for the experts, but the coloring doesn't look right to me. Check out this link: http://www.error-ref.com/improper-annealing/
Agree with the others. Staining/Environmental damage. There is no evidence on the edges that the color was there prior to coming in contact with the collar during striking and ejection
Shrews..... I have a suspicion that nickel may be coated with lacquer or shellac. And I'll tell you why.... I am an old woodworker and often make family keepsakes for folks. When I do something special like that I will drill in a recess for a cent, dime or nickel in a hidden place to show the year the item was created. I started doing that twenty years ago and recently have had a few items brought back to me for repair. And that yellowish tone is exactly what the coin looks like. Lacquer yellows over time. It's what gives wood that nice glow. I bet you could flick a bit of it off with your fingernail.
I also was going to comment that I can make visually coins just like that. You simply put a half, quarter(s), dime(s) or nickel(s) or whatever in a container with a cent, and add muriatic acid to it (Phosphoric Acid as found in Coca Cola can work too for longer periods such as the cup holder in your car). You'll get those inconsistencies dependent upon exposure times of your obverse which was possibly mostly covered by another coin. I have photos of stained coins in other threads, somewhere. The key per Fred in the copy of the article I linked to is the edge should not be the same color as the obv/rev after it's minted and ejected. But it could also be lacquer or gold. You'd have to figure that out.
Hey if it helps, I have had a coin just like that which was gifted to me a few years back from someone who also loved collecting coins.
