What is the tell-tale sign that a coin has been dipped, polished or cleaned? I have a 1927-S Peace dollar that looks like it is shiny or polished. When I compare it to another coin, there is something that looks funny about it. You don't see that unmistakable mint luster. I don't know how to post a picture, but any help or advice would be appreciated. I think I'll take it to my local dealer and see what he thinks as well.
I'm no expert on that subject but after many years of looking at coins I've learned that a cleaned coin usually has noticable wear and looks excessively brand new. Just out of the Mint look. If there is some dirt accumulation in little corners of the lettering, possibly not cleaned. The ones that are polished are really noticable since they look just like that, polished. Proof appearance and not a proof. Dipped coins are tuff pending how long they were dipped and into what. Example is a fairly new coin that was dipped in Acetone. I doubt any grading service would figure that one out. Someone I know dips most modern coins that are destined for a TPG and seldom ever come back cleaned. As to your 27S more than likely it was cleaned at one time but possibly not lately and just kept in an air tight invironment. At one time in our history it was common to clean coins. Dirty coins just did not sell and would not be wanted for a collection. So everyone cleaned coins. And the methods were really variable. So the possibility of yours being cleaned are pretty good and if a long time ago, normal.
Polishing a coin, over-dipping a coin, or dipping a coin too many times - all of these will remove mint luster. And of course harshly cleaning a coin will as well. As to how you tell - you tell just by looking at it. It's an experience thing, hard to describe but you know it when you see it. Just like you said, you can tell the coin does not have the luster - so either the coin is so worn that there is no luster left or one of the above was done to it. As to which one it was - it doesn't really matter since they all damage the coin in the same way.
I had a grader tell me that scratches in the same direction show cleaning. Seems obvious but theres my 2 cents.
shiney surfaces that are lacking in detail, grainy surface scratches, soil around the edges and raised legends of the coin but not on the flat surfaces, and diminished mint luster are all signs of a possible previous cleaning. The best way to learn the signs is through experience. Try cleaning a few coins in a variety of ways and you'll get a better idea of what to look for. Of course, don't practice on anything worth more than face value!
