Identifying #8
(#8 is a Type III)

#8 is a Type III design. The design on the sides are complete and the line at the top and the bottom is broken. This is different than Type IIIA where either the top and bottom line is broken, but not both.
Notes on #8
1) The degree or amount of the break in the line(s) is important. The greater the break the more desirable the stamp.

Position 99R II
The position with the largest break, hence the most sought after

Most examples (such as this one from plate IV) have
a large break in the top and a small break
in the bottom line.

Actual example of 99R II
MH sold at Siegal's Auction in Spring 2009 for $52,500
and a used copy sold for $1,700 in the Spring of 2008.
2) Plate V stamps look very much like Plate III stamps except that the side ornaments on Plate V are slightly trimmed. Plate V stamps are also all perforated. Beware of plate five stamps with their perforations trimmed off and impersonating the more valuable plate III stamps.
3)
Position 44L4 in the later printings can have breaks in the lines almost as large as 99R II. It is considered almost as desirable.
4) A certificate is required.
How many plates does #8 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)