1820 25C Medium 0 MS63 认证号25695453, PCGS号515284

Heritage Comments: 1820 Medium 0 Quarter, MS63 B-3, Border Toning 1820 25C Medium 0, B-3, R.3, MS63 PCGS. Tompkins Die State 2/1. Browning-3 is the only variety classified as Medium 0. Mint State pieces are rare for this variety, and they are scarce for the 1820 Capped Bust quarter in general. This satiny stone-gray coin displays lustrous interiors with deep ebony-gray border toning. Abrasions are minimal. Coin Index Numbers: (Variety PCGS# 515284, Base PCGS# 5329) Weight: 6.74 grams Metal: 89.24% Silver, 10.76% Copper

Ron Guth

1820 Quarter Dollars are divided into two major varieties: Large 0 and Small 0, both referring to the size of the final digit of the date.  The Small 0 variety is comprised of the Browning 4 and Browning 5 varieties.  For the Large 0 variety, PCGS recognizes Browning 1, Browning 2, and Browning 3.  Tompkins (2008) calls Browning 3 a Medium 0, which is justifiable: on the Large 0's, the inside of the 0's is oval in shape; on the Medium 0 and the Small 0's varieties, the right and left sides on the inside of the 0 are straight while the top and bottom are rounded.

Here's an attribution guide for 1820 Quarter Dollars:

Large 0 will have Large Stars
Small 0 will have Small Stars
Mediium 0 will have Large Star and a short serif at the top of the 1

Sources and/or recommended reading:

Tompkins, S.M. (2008).  Early united states quarters 1796-1838.  Sequim, WA: Destni, Inc.