the confusion seems to lie in the hands of the individual collector. How a coin is graded by individuals with different opinions on the subject of whether a coin has naturally toned ,a purist would argue, as in a case,or holder. The other half of the debate is artificially toned coins , as with heat chemicals ETC.Collectors who are a lot less picky about the hows and whys of the hobby, and just like the look of a coin. Then somewhere in between, is the environmentally toned coins. Air water,earth,A gray foggy area of the hobby that is still an ongoing debate. . The process , for all three types of toning(or corrosion) are different, therefore they create a different type of toning. The crux of the matter really comes down,in my opinion, to quality of the piece, and eye appeal, but thats just me.Others would argue that, a true tone would have to be natural, as opposed to environmental, like water, or air,or artificial on the other end, the chemically treated, or heated coins, which do create beautiful toning, but its NOT natural! An older touched coin can tone amazingly over time, as well as a capsulized one, which slows down the process considerably.