I did appreciate this conversation, so I came back to say so. The toning is IMO just evidence of oxidation and exposure. If you are dedicated to truly preserved pieces there should be no toning at all. It can be considered unlikely a 100 year old piece can meet that requirement, so the other option is to accept the "patina" as gracefully aged. More modern coins will be more likely to survive with no sign of toning or better to say "well preserved". Sometimes you just want an old coin to look old. I do enjoy my old looking coins. I can not hide the fact that they are old and so feel compelled to exploit it. Yes a truly MS coin should be exactly that, the state in which is was minted.