1807 50C Large Stars 50/20 AU55 认证号10839522, PCGS号6086

O-112, Rarity 1. CAC Approved. From Heritage's 2009 March Baltimore, MD Signature US Coin Auction #1126, Lot 1934. Golden-brown and ocean-blue adorn the reverse margin, while the obverse is comprehensively toned in gunmetal-blue and cream-gray. A slender strike-through (as made) reaches the S in PLURIBUS, but actual marks are minor and hard to locate.

Ron Guth

This is one of the great "oops" varieties of the early 1800s.  On this reverse, the engraver started punching the denomination into the die, but made the mistake of picking up a punch for a 2 instead of a 5.  Once the error was noticed, the engraver punched a 5 over the 2, but traces of the 2 remained under the 5.  The undertype can be seen even on coins in grades as low as Good. 

The 50/20 variety is slightly scarce, but can be found in most circulated and even Mint State grades.  The PCGS CoinFacts Condition Census includes coins ranging from MS64 to MS66.