The 1851-O half eagle is, like the quarter eagle of this date and mint, a scarce and curiously overlooked issue. There are approximately 125-150 pieces known and most of these are in the Very Fine to Extremely Fine grade range. In About Uncirculated, this is a rare coin with just fifteen to twenty coins known. Mint State 1851-O half eagles are, like all New Orleans half eagles from the 1850s, very rare in Mint State. Five or six are known in Uncirculated with none of these grading higher than MS 62.