most probably a stupid question, but, does wiping down coins with a microfiber-cloth or any kind of cloth count as cleaning? i did this a few years ago to a 1888 $20 gold piece, i hope that wouldn't have damaged the value of it too much (it wasn't a higher grade, maybe around a AU-55, AU-58 according to the random ebay guy i bought it from.) because i plan on reselling it, maybe (i would rather keep it, but the money would help my personal situation a bit...)
Rubbing a coin can (and most often does) cause hairline scratches on the surface of the coin. Sometimes the hairlines are visible with the naked eye; sometimes they are only visible under magnification. Hairlines are considered damage and diminish the value of the coin. Don't clean - or rub - your coins.
