Just to confuse you a little bit more Mike.... Proof is not a grade. It is a method of manufacture. Most proof coins are multiple struck on highly polished dies. You can have a XF proof if some kid took a proof half dollar out of his father's coin collection and spent it in the candy store and the coin entered the usual commerce stream and became a circulated coin ... but it now remains a circulated proof coin. Usually the difference in price between proofs and uncirculated coins has to do with how many of each were made....