Yes, unintentionally, naturally toned through neglect and Mother Nature & Father Time. Apparently a combination of acidity of cardboard in the old cheap coin albums, humidity, chemical reactions and many, many years, even decades of time. I think the green tone comes from the 10% copper content. After over 60 years of amateur collecting, I just recently noticed the beauty in some toned coins. Toning ranges from "amazing" to "terminal" or rainbow to black. Even the low-end black terminal can reveal the rainbow to a good eye, in sunlight.