Ron Guth: The 1858/7 Flying Eagle Cent is the only overdate in this short-lived series; hence, it garners a lot of attention. The overdate is very subtle and can be overlooked easily, especially since the undertype begins to disappear on later die states. Look for the right tip of a 7 on the right side of the top of the second 8. Another identifier is a small, raised chip in the obverse field midway between the date and the eagle's underbelly. Finally, look for a broken wingtip just below the F in OF.
The Condition Census (Top Ten) for the 1858/7 Flying Eagle Cent consists of five MS-65s and five MS-64s (according to the PCGS Population Report as of Novermber 2011). Collectors recognize the 1858/7 Cent as a scarce variety, but the Population Report shows how rare it actually is. Less than 6% of all the 1858 Flying Eagle Cents turned out to be the overdate. Based on that comparison alone, the 1858/7 should be worth more than 16 times the value of a regular 1858 Cent!