1817/3 50C Capped Bust Half Dollar, O-101 NGC AU55

Rare and popular overdate in a grade that is much more affordable than mint state examples. This one features original greenish-golden patina on both sides. NGC has graded 15 as AU55 with 37 finer. Many available specimens are of a late die state, as is this one, in which an arcing die crack spans the reverse from letters 'ME to' numerals '50.' This piece also has interesting die clashes on both sides.

The first U.S. Mint in Philadelphia, where this rarity was produced in 1817. Image: usmint.gov.

There is some confusion over this interesting overdate. Numismatist Ron Guth explains:

The 1817/3 Half Dollar is an enigmatic overdate that defies explanation. If it were a leftover die from 1813, one would expect the 13th obverse star to show the notched point that is believed to be the "signature" of engraver John Reich. Reich resigned his position in March 1817, after which the notching of the stars ended. This suggests that the new engraver simply made an error by punching a 3 into the die, then corrected it with the proper 7 punch. But, why would the engraver have picked up a punch for a 3? That would have been an egregious oversight on the engraver's part, especially since he was four years away from a need for a 3, plus there is no U.S. coin from 1817 where a 3 might be used in either a legend, motto, or denomination.