I realize this is sort of a newbie question, but outside of obvious or subtle rub marks, hairlines/scratches, etc, what are some good telltale signs to look for to determine if a coin has been cleaned?
The abrasion marks are the most definite sign, others are more subtle. Halo's around devices show where the cleaning couldn't go, and an overall lack of any luster (strike luster and/or shine).
Can you see the pinkish tones in the vertical lines of the crest on the eagles chest? Tells me somebody likely had some jewelers rouge or polishing compound on this one a very long time ago. At the time they did a very good job as there are no detectable polishing marks on the piece. But you just can’t get the rouge out of all the nooks and crannies and the stuff always dries to leave a pinkish or white haze.
Over time a person learns what the natural color of a coin should be based on what type of coin and it's age.
Other than hairlines, here are some more telltale signs of a cleaning: AU/Unc. coins will have a lack of luster. (dipped) Coins will have a strange luster pattern. (whizzed) Color will be off. Cleaned copper coins, for example, will turn pink. A worn coin will appear very shiny like a mirror. (dipped) Not 100% of the time. Halos do not necessarily mean a coin is cleaned. One must rely on other factors to tell if a coin is cleaned.
Dipping will not make a coin "shiny like a mirror." it will remove tarnish but is more likely to make it look dull. Polishing will make it shiny.
