Early US stamps, especially those issues before 1900 are often scarce in multiple form: pairs, blocks, or strips of stamps. The earliest US stamps, those before 1870, are exceptionally difficult to find in multiples and they often command large premiums over the value of (say) four single stamps.
Centering is hard to judge in dealing with these multiples. Why?
There are multiple factors that cause stamps to vary in centering. Paper shrinkage, perforating wheels that are slightly out of line, misaligned subjects within the printing plate, and so forth are all causes of varying centering.
For example, letís take a pair of stamps. It is possible that the left hand copy is VF centering with even margins. However, the right hand copy may only be Fine centering with perforations hugging the side of the stamp design. How would you describe this pair of stamps? Would you take the best copy and call the pair VF? But that nagging copy on the right has perforations ready to eat into the stamp design. Do you call it Fine? But that VF copy on the left pays a penalty for being attached to a more poorly centered copy. Do you split the difference and call it F-VF?
In this case, I would split the difference and call the pair F-VF. In my opinion, the right stamp is just too far off center to justify a VF description. Calling it just Fine unfairly penalizes the left hand copy. More precisely, I would list this item and clearly describe that the left copy is VF and the right copy is only Fine. That way the buyer knows exactly what they are getting.
Large variances in centering within a pair of stamps is unusual. Itís unusual to find, say, a VF copy next to an AVE copy. More likely, youíll find, for example, a F-VF copy next to a copy that is closer to the Fine category.
When dealing with larger multiples of more than four stamps, variances in centering are more common. Really large pieces such as a strip of 20 stamps or a full pane of stamps will definitely have centering variances throughout. This is quite normal.
Should you separate the stamps into single copies and separate them by centering? Put all of the VF copies together, the F-VF copies together, and so forth. In my opinion, no. With very early stamps, youíre probably destroying value since multiples are rare or very scarce.
This is why expertizing agencies that grade stamps do not offer a graded opinion on multiples outside of coil pairs (which are ďnormalĒ multiples). Itís just too difficult to take, say, a block of 20 stamps that has varying centering and try to find an average. What if 10 stamps would grade VF individually and the other 10 stamps would grade F-VF individually? The average is what? Exactly!
When dealing with multiples of early US stamps, there is no standard to follow. Not all dealers handle the same item the same way. Take time to understand what you are buying. Be aware that the centering will vary, especially on larger pieces.