I come accross lots of statements along the lines of:

"An experienced collector will always be able to tell in a heart beat that a coin has been cleaned, thus rendering it valueless."

I'm not exactly that confident in my own abilities to spot a cleaned coin, hack jobs aside. I was hoping some CPers out there would be willing to share some pointers and maybe even some examples of cleaned coins.

Thanks!

- Lines under magnification
- "Lusture" is flat rather than "cartwheel"

great thread topic, sbs.

I was told that there are many small, sharp peaks on the surface of a coin that reflect light all over the place to give it a lusterous shine. If a coin has been dipped or cleaned, the peaks are rounded and the reflected light is less diffuse and more dull.

On old coppers you may get a "pink" instead of a nice brown

So much depends on the amount of cleaning, the method, the cleaning agent, etc. I myself have cleaned coins and sent them in to places like PCGS or NGC and some have come back cleaned and some didn't. I've known many others that have done the same thing. I've seen coins at coin shows that appeared to be cleaned but almost impossible to tell and I would ask to borrow one and show it to a dealer I knew well and ask if they thought it was cleaned and usually say not sure. I've had dealers I know show me coins they had cleaned and it just wasn't possible to notice since it was just a light claning bath in something mild or Acetone. Not long ago I purchased a 1914D Lincoln Cent that was at least MS something for a price that I couldn't refuse. Naturally the dealer told me it had been cleaned but for the price it was being offered, who cares. Then naturally there are the cleaned coins that you can see right away. They are usually a worn coin that appears to be new. Many claned coins take on unusal discolorations and many attribute that to just toning. So it is actually not the easiest thing to detect even by experts.
One of the nice things about being able to detect a cleaned coin is if not to harshly cleaned you can come up with some nice coins for a decent price. Then lay them on an indoor window sill in a kitchen area and they will tone down quite a lot. Kitchen due to all the miscellaneous gasses given off during cooking.