I've seen numerous Eagles that had that sort of look. I don't really like it, but I believe it to be natural toning.
I have seen numerous ASE's with that look and each time I see another, I become more and more suspicious about the origins of the toning.
Momma raise your child to be a coin doctor.... Do you realize how much that toning costs per oz?? According to White's "coin Chemistry" book, the average toning weight of this rainbow on a silver dollar size coin is about .0002 grams. If we assume the toning raised the price even $200, then that is $100/.0001grams or $1,000,000 per gram or $31,100,000 per ounce. "Tone" must be one of the most valuable substances in the world, certainly more than the per weight cost of the 1933 $20 gold piece. Jim