1945-S Mercury Dime 10c MS66 FB NGC 943289-2
The Micro S mintmark, unique to 1945 within the Mercury series, is not rare but is very popular with collectors. It was almost certainly an error to utilize this punch in preparing dime dies, yet several such dies were employed during 1945. This mintmark was prepared in 1907 for identifying coins struck at the San Francisco Mint that bore designs unique to the Philippine Islands. The 1945-S dime is the only regular issue type known to have been coined with this tiny letter S.
Though examples are fairly plentiful in grades as high as MS 66, the certified population drops off quickly above that level. Since 1945-S dimes of all varieties are poorly struck in most instances, the Micro S issue is exceedingly rare with full bands.