Looks like something protected the original finish in certain areas and later peeled/wore of the coin. It could have been something like a sticker that was left on for years and some areas were not protected and were affected through the time it was covered. A lamination tends to be in straight lines. I would like to see a close up of the tops of the wheat lines areas where the color changes. If the metal is missing and shows a step, then it would not be a color change issue. But it is a lamination and the metal is missing, then the weight should be off. Something else to consider?