David Hall: In circulated grades, the 1921-S is one of the rarest coins in the Buffalo nickel series. In Mint State and Gem uncirculated condition it is not quite as relatively rare, but is still very rare. In Gem condition, the rarest dates in the series are the 1918-S, 1919-S, 1920-S, 1923-S, 1924-S, 1925-S, 1926-S, and 1927-S. The 1921-S is the next rarity level as it is not quite as rare as those issues, but is very rare nonetheless. It is comparable in rarity in Gem condition to the 1919-D, 1920-D, 1925-D, 1927-D, and 1928-S. Strike is usually decent for a San Francisco Mint issue, though there are some survivors with weakly struck Buffalo's horn and tail. Luster is usually a subdued frosty look.