Centering and margins
The following grades convey how well centered the stamp is and the width of the stamp's margins.
A or AVG (average)
Is a stamp that has almost no margin on at least one side with a portion of the design trimmed off or cut into by perforations. Except for rare or very old stamps average stamps are not collected or sold except as space-fillers or reference copies. Heavy cancellations which obliterate the design can also be considered.
F (fine)
Is a stamp that is significantly offset but still has four margins.
F/VF
Is a stamp with the design almost centered both vertical and horizontal.
VF (very fine)
Is a stamp with the design almost centered horizontally and perfectly centered vertically.
XF (extremely fine)
Is a stamp with the design almost centered vertically and perfectly centered horizontally.
S (superb)
Is a stamp perfectly centered.