Identifying #8A
(#8A is a Type IIIa)

#8A is a Type IIIa design. The design on the sides are complete, the line at the top is broken and the line at the bottom is barely broken. This is different than Type III where both the top and bottom line is broken.
Notes on #8A
1) The degree or amount of the break in the line(s) is important. The greater the break the more desirable the stamp.
2) Plate IIIa stamps look very much like the valuable Plate I stamps in so much as the balls at the bottom have traces of ink, giving the impression of a complete bottom design, but on close examination you will see that the traces are too faint to qualify for a complete design.
3) A certificate is required.
How many plates does #8A appear on?
Three plates. Plate 1 early, plate II and plate IV.
The design of this early issue was too large to allow for the accommodation of the 200 subjects onto one plate. Therefore, each position had to have some amount of the design erased to allow enough room. These erasures accounted for the majority of the types.
What exactly do the plate position numbers mean?
To take the example of 7RI1
7 = Seventh stamp of the 100 on the pane - this number can be from 1 to 99.
R = Right Plane - this letter can be either R or L, L representing the Left Pane
I
= Plate I, this roman rumeral can be I, II, III, IV, V, VII, VIII, IX, X, XI, XII
E= Early State, this letter can be either E or L, L representing the Late State. This letter is only appended to plate I stamps.
How many plates were there?
There were twelve plates of the 1c Franklin made, plate six was never used, probably due to it being damaged in it's creation. Most of the plates were used for both the imperforate and perforated design. Some only produced one type or the other. For instance, plate 12 produced only perforated stamps and the early state of Plate 1 produced only imperforate stamps whilst plate I late (reconstruction) produced both imperforate and perforated stamps. Plate 4 was the last of the imperforate plates to be used.
Rescources available
http://www.slingshotvenus.com/FranklinArchive/frnkln_archv_Main.html
Stanley B. Ashbrook, The United States One Cent Stamp of 1851-1857.
Mortimer L. Neinken, U.S. One Cent Stamp of 1851-61.
The Ishikawa collection: United States 1851-1857 1 cent Blue Issue postage stamps in multiples and reconstructed plates.
Click here for a comprehensive, printable, identfication guide. Courtesy of Chris Biason (447kb)