Ron Guth:
Two major varieties comprise the 1819 Quarter Dollars: Large 9 and Small 9 (the Small 9 is called a "Normal" 9 by Rea et al). The 9 on the Large 9 is substantially larger than either of the 1's in the date; on the Small ("Normal") 9, the 9 is approximately the same hieght as the adjacent 1. The most common of the 1819 Small 9 Quarter Dollar die varieties (B-3) is very common; the other (B-4) is very scarce. According to the PCGS Population Report, the Small 9 is nearly twice a plentiful as the Large 9.
The PCGS CoinFacts Condition Census for the 1819 Small 9 Quarter Dollar includes coins from PCGS MS-63 to PCGS MS-66.