This is an 1820 Capped Bust Quarter in the B1 die marriage.  This example displays rich patina on it surfaces that one expects for an original, crusty VF coin from the early 19th century. Hints of aqua with a light touch of rose is exhibited in the obverse toning, with no detracting marks, and hence worthy of the CAC acceptance.
 
This is known at the Large  0 variety and is considered to be R5- in the Rea et al., Early Quarter Dollars of the United States Mint book.  The R5- rating estimates that 61-75 of these still exist.  Based on the rarities of the 5 die marriages for this date, there are around 2000-3000 extant so this means that ~2-5% of all of the 1820s are B1's.  Die marriage B2 is also a Large 0 marriage but has a different reverse die and is an R2 with ~750 to 1000 extant.  The B1 reverse die is identified from the placement of the Scroll beginning right under the left edge of D (this one), whereas the B2 Scroll begins between the E and D of UNITED.  B2 also has a distinct die line from the 3rd olive leaf to the left of 25C and into the dentils.  This die line is not present on the B1 as observed in this example.
 
CAC has stickered or slabbed 65 Large O 1820 bust quarters. Based on estimated populations of the 2 die marriages of B1: 61-75, B2:750-1000, we calculate that 6 to 10% of the CACed Large O's, or ~4 to 7 of these are likely B1.  Hence, there are just not to many around with the surface qualities that meet the expectations of the CAC/CACG grading teams.  
 
This coin has been approved by CAC.
 
PCGS Cert. #30801637