Here is a nice Example of toning of a silver coin.  This is a 1995 Mexican One Onza, more commonly called a Libertad. It is Mexico's answer to our Silver American Eagle. One ounce of .999 pure silver. These are very popular coins that I collect. The 1995 is the last year they were minted in this diameter, 36 mm.. After that they were and are made to 40 mm.. The obverse features the national coat of arms. The reverse shows the Winged Victory Statue and the mountains Ixtaccihuatl and Popocatepetl. These mountains have a very interesting story associated with them and I encourage everyone interested in Mexico and their coinage to research it. Now to the toning. Look at the progression of colors and their shape and you will see a perfect example of how they should appear on a coin. There is a natural pattern and order of colors.  Often, on counterfeit coins, they get the colors and their progression wrong. Very often they are falsely toned to hide imperfections in the fake coin it self. The ANA Summer Seminar has a class on this very topic.. If you enjoy toned coins of any type, you might consider taking it or something like it. Counterfeits are everywhere, even inside slabs! Thanks for looking. As always I look forward to your comments.