This is a new Belgium coin and it's just stating to get that golden hue on the reverse side. On the face is a wrinkle in the plastic no on the coin.
OK, I tracked down the pictures...here are the "best of the best" from my personal collection of toned world coins. They are in date order (oldest to youngest):
Italy... the toning on this coin really takes my breath away. 1 of my favorite toners... even better in person.