Now the humidity in the air or if the coin book gets wet, it releases these gases and depending on the contaminates in the air, the coins can turn into all sorts of colors on both sides. Over the last 40 years, I have purchased thousands of rolls of silver dollars in their original paper bank rolls and in almost every case the two end coins that were opened to the air were toned, some in rainbow colors, some dark gold or even black. Coins coming from highly polluted atmospheres like Los Angeles, Seattle, Portland, or the South where they also have very high humidity rates also tone rapidly. Many people and especially new dealers think this toning devalues the coins and dip them with silver dip to make them white again. Many experienced collectors would rather have toned coins than dipped or cleaned coins.
Most dealers collect nice examples for their own collections.
Toned and frosted proof like coins are one in a thousand and each one is truly unique unto itself. In other words, it's the only one like it in the world. Of course it takes a special kind of buyer or collector to recognize this, but if you watch our silver dollar list, you will see them disappear one or two a day. First - Proof Like Morgans, then Toned Morgans, then Frosted Coins. Not because they have any more profit in them, but because they are the prettiest and the rarest.