What causes coin toning? Can coin toning be enhanced? or altered? Why do some coins tone and other do not? Why do some coins tone faster than others? How long does it take to tone a coin? Under natural circumstances? Which coins tone more often? Penny's, nickels, dimes, quarters, half dollars? Which alloys in coins tend to have more toning than others? Copper, Silver, Nickel, Other?
All coins start toning the second they hit the air . O2 & sulfides in the air start reacting with the silver & copper , it's worse in areas with bad pollution & near sea water . rzage
I've had Unc. silver coins turn black on their backs in months , they were in a nice looking 20th Century Coins Wall plaque made of cardboard , high in sulfur . rzage
All coins tone to some extent, with copper the most and gold the least (I think). Some people like me like natural toning, others do not. Sometimes and ugly toned coin will lower the grade a little from grading services. Grading services will reject artifically toned coins. Usually people artificially tone coins to hide cleanings or flaws in the coin. http://rg.ancients.info/guide/toning.html http://www.omnicoin.com/news/Numism...TruthAboutCleaningCoins/tabid/48/Default.aspx
