Does faint spotting on silver affect the grade? I have a 1982 unc George Washington commemorative half dollar and it has a few very small spots that are barely visible without magnification. Otherwise there are no bag marks or scratches. I just wonder if a coin is MS-67 and then develops spots like that, could it drop to, say, a 66 for that reason?
It's in the mint plastic and you won't be able to see it from a picture. I take back the spots being yellow. They are white and look like water spots.
Sounds like you are describing milk spots. They often develop on commems and bullion coins. There is nothing that will remove them and yes they do affect the grade.