Ron Guth
The 1866-S Dime is a low-mintage date relative to other series, but the mintage is typical of S-Mint Dimes from the early to mid-1860s, and a very high mintage compared to the 1866-P (135,000 to 8,000, respectively). Based on the mintages alone, price guides have always presented a higher value for the lower mintage 166-P. However, the advent of Population Reports, after a 25+ year record of coin grading, show that the 1866-S is actually scarcer than the 1866-P in Mint State. In addition, the highest-graded 1866-S Dimes are two points less than the highest-graded 1866-P. For the 1866-S Dime, the best examples available to collectors are a pair of MS-65s, one of which is illustrated above.
Some examples show a wavy, vertical crack that nearly bisects the obverse.
#1 MS65 PCGS grade