Was going through my 1956 dimes looking for dot varieties. Found 2 not a problem identifying those but came across this. Is it PMD or something else? The mark under the 5. Sorry I couldn't get better pictures I usually rely on extra sunlight too, none of that right now.
Dots and spots like these are quite common and minor according to Zoell. He has one listed like this as B279f in his Minor Coin Varieties booklet. He also has about thirty different dots and spots varieties none make it to his Major Variety booklet.
Well, up until about 8 months ago I had the Zoell catalogs for Major and Minor; then WHAM--they are no longer in my library. Disappearance still a mystery; maybe got discarded in office/library reorganization? Guess we'll never know. To answer your question: owners of these now consider them to be 'nuggets of gold' and price accordingly. They are extremely scarce to find. Good luck. Frankly, I won't lay out $100 for one; I'm too cheap.