when i first started collecting i cleaned a bunch of early date lincolns with a pencil eraser and i cleaned some v nickels and buffalo nickels with brasso.
Here's the coin in question. http://i182.photobucket.com/albums/x275/clembo1872/scan0004-5.jpg Now I was six when I did this and it has still not retoned after 40 years but is a good reminder. Hey kids! Don't do this at home!
Different era. No guidance, cleaner came with the set and certainly no internet. This would hurt a lot more if I did it six months ago. Information is easily accesible now.