Ron Guth: The 1921-S Cent is a relatively plentiful date that can be found with ease in Brown and Red-Brown grades all the way up to MS64. After that, the populations drop off rather quickly and, in fact, none have been certified by PCGS in MS-66 or better grades - in ANY color format. Keeping in mind that many of the highest-graded coins are being resubmitted in an attempt to garner the elusive MS-66 grade, the MS-65s may be even rarer still. Strike-wise, the 1921-S looks pretty good -- on par with the 1921-P and much better than some of the later S-Mint Cents from the 1920's. As always, collectors should look for coins with the most color, the best definition, and the least number of carbon spots.