Grade & Condition - The grade and condition of stamps greatly determine their value.
Grade addresses only centering and cancellations. Condition refers to the factors other than the grade.
Dealers grade by the following criteria as written in the Scott Catalog
(1997 Edition – Copyright 1996 by Scott Publishing Co.):
Fine: designs that are noticeably off-center on two sides. Imperforate stamps may have small margins, and earlier issues may show the design touching one edge of the stamp design. For perforated stamps, perfs may barely clear the design on one side, and very early issues normally will have the perforations slightly cutting into the design. Used stamps may have heavier than usual cancellations.
Fine-Very Fine: Somewhat off center on one side, or slightly off center on two sides. Imperforate stamps will have tow margins of at least normal size, and the design will not touch any edge. For perforated stamps, the perfs are well clear of the design, but are still noticeably off center. Used stamps will not have a cancellation that detracts from the design.
Very Fine: May be slightly off center on one side, design will be clear of the edge. Will present a balanced appearance. Imperforate stamps will have three normal-sized margins. Used stamps will have light or otherwise neat cancellations.
Extremely Fine: Close to being perfectly centered. Imperforate stamps will have even margins that are larger than normal. Even earliest perforated issues will have perforations clear of the design on all sides.
Factors that can improve the value of the stamp include:
Factors that may decrease the value of a stamp include:
(These criteria are generally standard, however, Scott acknowledges that there are no official standards for grading, and the prices they estimate are variable based on the dealer you purchase the item from.)