Ron Guth: The 1861/0 Half Dime is a true overdate, with the 1 punched over an underlying 0. The shape of the o is a bit amorphous, but is readily visible on high-grade examples. This is a relatively scarce variety that shows up at auction approximately 5-10 times per year (often less). PCGS has certified over 100 examples (as of February 2012), but less than half of those are Mint State. The finest examples certified by PCGS included 2 MS-67s.