David Hall: The 1921 Peace dollar is a very interesting and extremely important coin. It is, of course, the first year of issue for the Peace dollar series. Slightly over a million pieces were struck, a modest mintage for a silver dollar. But the 1921 was struck in very high relief, not unlike the 1907 High Relief $20 St. Gaudens. For many years the 1921 was not recognized as a separate type coin, although it clearly is such. The PCGS founders, along with the experts on the PCGS (and now PCGS CoinFacts) Board of Experts, confronted the lack of recognition for this coin shortly after the 1986 launch of PCGS. We all just started listing the 1921 as a separate type and the numismatic community soon followed suit. So the 1921 is now important as both the first year of issue (and one of the scarcer issues) for the Peace dollar series, and as a very important one-year-only 20th century silver type coin.
The 1921 is one of the scarcest Peace dollars in both circulated and mint state condition. In Gem condition it is scarce, but not quite as rare as some of the usually very weakly struck S Mints such as 1925-S and 1928-S which, because of strike, are very rare in Gem condition. Because of the high relief of the 1921, strike can definitely be a problem. The majority of mint state specimens show weakness in the central devices, i.e. Liberty's hair and the eagle's feathers. Well-struck Gems are definitely the exception.
Luster can vary on this issue. I have seen many that are white and quite frosty and I have also seen many that have a very satiny look. Toning is not uncommon and is light to heavy golden.
Note that I am of the very strong opinion that any 1921 Peace dollar...indeed any Peace dollar...that has any rainbow colors (blue, red, green, etc.) is absolutely artificially toned. While not very scientific, my approach to toning on coins is to remember the colors I saw in the 1960s and 1970s and if a new look appears, it's artificial to me. This is kind of an "old school" approach and I may be wrong, but unless you believe global warming has created new colors for coins, it just seems illogical to me that new colors would suddenly appear naturally on coins.
Back to the 1921 Peace dollar...this is, in my opinion, one of the most important coins of the 20th century, and also one of the most beautiful.