Mercury Dimes, What Do You Consider The True Key?

Thanks Carl, that is good input! I agree the 31D is very common. Especially in lower grade. I still gobble all branch mint pre-34s that I can. I expect that one day after the scrapping frenzy has pulled them all out of the cupboards and sent them to the smelter that the prices will start to rise back up. I do get a lot of 21Ds...but all in lower grades. I notice that on average the prices for the 21 and 21D have gone down in the real market place.