What's the Difference? Part 1

by Peter Torraca

Almost daily we receive questions by email from new collectors or people who have inherited stamps. Most of the time, these questions boil down to something like: "How do you tell one stamp from another? They all look the same!" Of course, such questions are not literal as many stamps differ in obvious details like face value, design and country of origin. Frustration usually sets in when a new collector tries to distinquish between two or more stamps which look very similar, but seem to have very different in values in the catalog.

Anyone who has tried to use a stamp catalog to figure out the identity and value of their stamps has run into the problem that one illustration in the catalog is used for two or more stamps. (They have probably also run into the reality of the stamp market, see "About those catalog values" for more information on values) Since one of these varieties is inevitably more valuable, beginning collectors or non-collectors almost always make the mistake of assuming that the stamp they have is the valuable one. It is the unfortunate role of a dealer or knowledgeable collector to tell them the truth.

So what is the difference between these similar looking stamps? Let's use a group of fairly common US stamps for illustration. Though these happen to be US stamps, the ideas here will apply to stamps from any country. Take a moment to examine the illustration on the right. The Scott catalog uses the same illustration for each of these stamps, but lists them differently. Why?

Perhaps the first thing you noticed is that two of these stamps (E and F) are used. That is, they have cancellation marks on them. This difference is one of condition, not identity. Condition will come in to play when we talk discuss value, but for now we'll disregard the fact that they are used.

For most similar looking stamps, the main difference lies in their perforations. Perforations or perfs are those little ridges that border the outside edge of the stamps. Notice that one stamp has no perfs and another has perfs only on two sides. The stamp without perforations, C, is called an imperforate or imperf stamp and the other one, D, is called a coil. Imperf stamps are usually collected in pairs or single stamps with very large margins because they can be easily faked by trimming the perforations off of a perforated stamp. (Want to know more about faked stamps? Check out the Henry Gitner's Hall of Shame).

Coil stamps, are those with perforations on only two sides. They were originally created and sold for use in vending machines. You can still buy them individually from vending machines today, but you can also purchase a full coil from the post office. Coils come in two flavors, horizontal and vertical. Horizontal and vertical refer to the sides of the stamp have perforations. That is, a vertical coil will have perfs on the vertical sides of the stamp; a horizontal coil will have perfs on the horizontal sides of the stamp.

There are also important distinctions between fully perforated stamps. Perforations come in different sizes. You can measure perforations by calculating how many perfs (tips or wells) are in a 2cm section of a stamp's edge. Sounds pretty painful, huh? Fortunately, collectors have a special tool designed just to measure the perforations of a stamp. It is called a perf gauge. We recommend gauges similar to the one illustrated below (Linn's, Stanley Gibbons, and others make excellent perf gauges. Ask your favorite dealer or stamp supply source about them):

Using a perf gauge is simple, you simply location the place on the gauge where the tips or wells of a stamp's perfs line up with the indicators on the gauge. If you were to do this with stamps A and B above, you should see something like this:

Stamp A measures out to be a perf 11, and B measures to perf. 10.5. In terms of identification, this is a significant difference. In some cases this small difference in perforations can represent a significant difference in value (in this case the difference is not great: A, Scott 554, = $2.20 and B, Scott #634, = $0.15)

So we see that based on the perforations alone, 4 of the six stamps above are quite different animals. The 5th and 6th stamps, E and F, are rather different too, but we'll talk about those and more next time. You can continue reading with What's the Difference? Part 2