Haven't been a big fan of toned coins up until this point. I'm sitting at my desk looking through my pile of Mercs that I have been buying at melt from my dealers junk tray. Really like the Merc design and have just been buying whatever he might have. As I have been looking through them, I have some that are really nicely toned. Greens, pinks, oranges all through the obverse of the coins. As I look at the grading guidelines in my Red Book, I'm thinking some of these are in the G-4/VG-8 range. Will the toning on the coins make the coins more valuable? Or, does toning on junk or near junk coins not really matter?
Toning will really only fetch a premium if the coin itself is of a high grade, AU,rare coin or a key date. I personally would not pay a premium for any toning on a low grade coin, unless the toning really stuck out. This has only happened once for me. I paid $3 over melt value for this nickel due to it's beautiful, vibrant toning:
Circulated toned coins are rare but they do exist. FWIW, I have seen this on Mercury Dimes more than any other series. Here is an example: However, I very much doubt if it will significantly raise the value of the coin.
Unless the toning is absolutely gorgeous on the circulated mercs, I don't see them gaining much in value. As Lehigh stated above, mercs do tone a lot, even in circ. grades. Here's one of mine, kinda golden.
I think there's a good deal of value in toned "junk" coins. You get all the pretty colors of toning with little of the premium.
Well, most junk silver has been out of circulation for more than 40 years, much of that time just spent in one hoard or another - plenty of time for them to tone up I would imagine, although I don't see that many examples.