A couple of days ago I got a box of 5,000+ cents. It wasn't just random wheats, but somebody's personal collection of IHP, wheats, and Memorials. The lot contains a HUGE amount of beautifully toned pennies in just about every shade of the rainbow.
My question involves how to tell the way in which a coin tones. Apparently this collector didn't read up on coin collecting before he started and 90% of his best coins were cleaned. The bulk of the collection is uncleaned, but most of the "best" coins are visibly cleaned to the point that they look yellowish and brassy. What I can't tell is if all of these GORGEOUS toned coins are actually part of the "cleaned" coins and the cleaner caused some of the coins to tone. Does this happen or is it safe to assume that they toned naturally? Is there a way I can tell whether the toned coins are natural?