Images courtesy of Superior Galleries

Significant examples:
PCGS Chapman Proof 66, Superb!  Ex - Superior Galleries' "Pre-Long Beach Sale", October 1-3, 2000, Lot 3768, sold for $60,375.00 - Legend Numismatics

NGC Proof-65, Zerbe.  Ex - Superior Galleries "Pre-Long Beach" Elite Coin Auction, May 25-27, 2003, Lot 3143, sold for $8,912.50

NGC Chapman Proof-63 (illustrated above).  Jack Lee collection - Superior Galleries' "Pre-Long Beach" Sale, June 5-7, 2000, Lot 1866, sold for  $13,225.00 "to the book"

PCGS MS-67.  Superior Galleries' "Pre-Long Beach" Sale, June 5-7, 2000, Lot 1867, sold for $6,842.50

Brilliant Proof 65, Zerbe Proof.  Ex - Stack's "65th Anniversary Sale", October 17-19, 2000, Lot 1215, plated, sold for $3,220.00  From Superior's Sale of the Wayne Miller Collection, January 1986, Lot 1400

Brilliant Proof, Zerbe Proof.  Ex - Stack's "The University of Notre Dame Sale", March 20-21, 2001, Lot 563, plated, sold for $3,220.00  Ex- Autumn Sale, Stack's September 1978, lot 430

Recent appearances:
PCGS MS-65.  Ex - Superior Galleries "Pre-Long Beach" Elite Coin Auction, May 25-27, 2003, Lot 3145, sold for $8,912.50

PCGS Proof-65 Zerbe.  Ex - Bowers and Merena Galleries' Robert W. Schwan Collection Sale, October 26-27, 2000, Lot 1596, unsold

PCGS Proof-65 Zerbe.  Ex - Ira & Larry Goldberg Coin & Collectibles' "The Fairchild Family Trust Collection Sale", May 28-30, 2001, Lot 1042, illustrated, sold for $8,913.00

PCGS Proof-64.  Ex - Superior Galleries "Pre-Long Beach" Elite Coin Auction, May 25- 27, Lot 3141, sold for $36,225.00

PCGS Proof-64 Zerbe.  Ex - Ira & Larry Goldberg Coins & Collectibles, Inc.'s "Benson Collection, Part I", February 16, 18-20, 2001, Lot 2210, illustrated, sold for $4,830.00

NGC MS-66.  Ex- Heritage Numismatic Auctions, Inc.'s "October 2000 Long Beach Sale" October 5-7, 2000, Lot 8487, not illustrated, sold for $506.00

NGC MS-66.  Ex - Heritage Numismatic Auctions, Inc.'s "Long Beach Signature Sale", May 31-June 2, 2001, Lot 6660, not illustrated, sold for $690.00

MS-65.  Ex - Ira & Larry Goldberg Coins & Collectibles, Inc.'s "The California Sale", October 2-3, 2000, Lot 1848, unsold

PCGS MS-64 DMPL.  Ex - Bowers & Merena Galleries' "The Cabinet of Lucien M. LaRiviere, Part II", March 15-17, 2001, Lot 587, sold for $2,990.00

PCGS MS-64 DMPL.  Ex - Heritage Numismatic Auctions, Inc.'s "Long Beach Signature Sale", May 31-June 2, 2001, Lot 6661, illustrated, sold for $2,070.00 From the holdings of Andy Hansen

MS-63.  Ex - Bowers & Merena Galleries' "The Lake Geneva Sale", June 28-29, 2001, Lot 1162, not illustrated, not sold

ANACS MS-62.  Ex - Heritage Numismatic Auctions, Inc.'s "Long Beach Signature Sale", May 31-June 2, 2001, Lot 6659, "Zerbe Dies", not illustrated, sold for $690.00

AU-50.  Ex - Bowers & Merena Galleries' "The Cabinet of Lucien M. LaRiviere, Part II", March 15-17, 2001, Lot 588, unsold

Notes:
The finest Uncirculated examples graded by PCGS are 6 MS-67's, a single MS-67 Prooflike, and 5 MS-64 Deep Mirror Prooflikes.

Proof examples of this date are quite different from those of earlier dates.  Two Proof versions of the 1921 Morgan Dollar  were struck, both apparently at the request of individuals outside the Mint.  

The first version, known as the "Zerbe" Proof, was struck for the noted numismatist, Farran Zerbe, who supposedly had a fit when the new Silver Dollars of 1921 turned out to be a resurrection of the Morgan Dollar type instead of the new Peace Dollar type that he had promoted.  The exact mintage is unknown but the figures bandied about in the past have ranged from a low of 20 to a high of 200.  PCGS has certified 78 "Zerbe" Proofs, the finest of which have been 7 PR-66's.  Breen noted that most of the "Zerbe" Proofs he had seen had been cleaned or scrubbed, but his experience conflicts with PCGS' findings (PCGS will not certify cleaned or impaired coins).  

Breen offered some die characteristics of the Zerbe strikings, but be wary, as circulation strikes also exist from these dies:

"Obv. Small die scratch up to r. from left tip of serif of left upright of second U in UNUM to border.  Left base of first 1 above center of dentil, r. base of second 1 slightly r. of left edge.  Central details far sharper than on regular uncirculated pieces.  Rev. Very faint recutting visible on left upright of T in UNITED.  Horizontal die file marks plainly within ribbon bows and at left and right of them; vertical die file marks at inner berries nearest to left base of N and T in UNITED.  Eagle's breast feathers unusually sharp.  Brilliant proofs as in 1904 and earlier years, carelessly made..."

The second Proof version is the so-called "Chapman" Proof, named after the Philadelphia coin dealer, Henry Chapman, whose name appears on a Mint invoice (dated June 11, 1921) selling him "10 proof silver dollars 1921".  For years, the mintage was thought to have been limited to only the ten coins, but now we know that additional "Chapman" Proofs were struck.  PCGS alone has certified 40 examples, the finest of which is a single PR-66 that far outshines the 13 PR-64's that are at the next level below. The only Proof Cameo example graded by PCGS is a single PRCA-64. "Chapman" Proofs are super brilliant and have only 16 berries in the wreath on the reverse, as opposed to 17 on the "Zerbe" Proofs.  Additional die characteristics include a hollow area around Morgan's initial on the truncation line on the obverse (caused by die polishing) and light die striations around UN, AM, and RICA on the reverse.  

Sources and/or recommended reading:
"The PCGS Population Report, April 2003" by The Professional Coin Grading Service

"Walter Breen's Complete Encyclopedia of U.S. and Colonial Coins" by Walter Breen

"Walter Breen's Encyclopedia of United States and Colonial Proof Coins 1722-1977" by Walter Breen