The three key dates are 1896-S, 1913-S, and the King of all regular issue Barber coinage, the 1901-S.
The 1901-S and 1913-S are two of the three lowest mintage dates of 20th century minor U.S. coins, with just
72,664 and 40,000 minted, respectively.
When obtaining the Big 3, you must make sure the coins are genuine. While only a few fake 1913-S have been seen, there are plenty
of fraudulent 1896-S coins (most with an added "S"). And fake 1901-S coins outnumber genuine specimens in G to VG grades!
Although the "Big 3" get most of the attention, many of the other dates in the Barber Quarter series
are extremely difficult to find in higher circulated grades,
including 1896-O, 1897-O, 1897-S, 1901-O, 1905-O, 1909-O, and 1914-S. As a result, putting together
a complete set of Barber Quarters in higher grades
is not only expensive, but takes a lot of serious searching and a great deal of luck. Perhaps only 12 to 15 original
AU 1909-O quarters exist, making it quite possibly the 2nd or 3rd most difficult coin to obtain in that grade. That's rare.
For information on grading Barber Quarters, please see the Grading Barber Quarters page.
A rarity rating survey was conducted among BCCS members a number of
years ago for circulated Barber quarters. In 2006, the Society updated the survey with
much more detailed information, including more specific grade ranges, additional varieties, etc.
Look at the
2006 Rarity Ratings Survey for Barber Quarters
For information on authenticating the "Big 3" see also:
The best single reference on this series is Complete Guide to Barber Quarters, 2nd Edition, by David Lawrence, with
detailed information about the series, and date-by-date analysis. This is an indispensible reference for the Barber Quarter