In order to get a proper value for a given stamp, you of course have to first identify it.
Sometimes merely seeing the design on the front of the stamp is enough, but oftentimes, especially for older stamps, a detailed set of checks must be made to determine exactly which stamp you have.
There are countless examples where a very common stamp will look just like a similar rare stamp, and the only way to differentiate the two is by getting a proper identification.
We’ll cover some of the basics to get you started here.
Perforations #
Generally the first thing you need to check is a stamp’s perforations (aka, ‘perfs’).
These are measured using a tool called a perforation gauge. If you inherited your stamps from a collector, they may have one of these tools with the collection.
If not, they are widely available on numerous sites that sell stamp collecting supplies.
If you have a printer handy, you can print one out for free here. Use this tool to measure the perforations of the stamps.
Here’s a quick video describing how to use the tool.
When describing the perforation of a stamp, you may see terms like:
- Perf 11: perforated 11 on all 4 sides
- Perf 10½ x 11: perforated 10½ on the top and bottom, 11 on the sides
- Perf 8 vertical: perforated 8 on the sides, but the top and bottom with no perforations
The numbers will differ of course, but these are the ways stamp perforations will be described. When 2 numbers are listed, it’s always the horizontal perfs (the top and bottom) listed first.
Watermarks #
Sometimes what separates a rare stamp from a common one is a watermark in the paper. You can find one of these using stamp watermark fluid, again, widely available on many stamp collecting supply sites.
You can also use other products like lighter fluid to see a stamp’s watermark.
Place the stamp, face-down in a dark tray (these often come with the watermark fluid) and drop a few drops of the fluid on the back of the stamp.
After a second or two, the watermark, if present should be visible. Note that you may only get a portion of the full watermark on any individual stamp, so this can be tricky to see for sure.
Also note that different countries use different styles of watermarks, so consult whatever resource you are using to know exactly what kind of watermark to look for.
Printing Methods #
Stamps are produced in a number of different methods. Some of the most common are called Flat Plate and Rotary Press.
We won’t get into the actual printing methods involved, but for identifying a stamp you need to know that these methods can produce stamps that look similar, but the size of the printed design can slightly differ.
This is a frequent area of incorrect identification, because the difference in size between the two is slight. s that describe these stamps may list their sizes in millimeters, often fractions of millimeters.
It is not advised that you try and measure this yourself, even using software that may scan the stamp and try to measure it. The best way to check this is by comparing 2 stamps: compare your unknown stamp with a stamp from the same series that you can know the printing method of.
This is known as the ‘template method’, there’s an article that describes this method here.
Color #
Sometimes the color of the ink used on the stamp is the critical piece for identification. This can be difficult to determine for a number of reasons. First, a stamp color can change over the years.
Exposure to light, chemicals, improper storage, etc., may change the way the stamp originally looked into something different.
Second, the names that catalogues may give to stamp colors may not be readily obvious. Colors may be listed using esoteric terms like ‘pigeon blood pink’.
Or you could see similar stamps described as ‘blue’ and ‘deep blue’.
Compounding this, if you try to take a picture/scan of your stamp and post it online looking for color advice, factors such as your camera/scanner and my phone/monitor may mean that what I see on my end may not be an accurate representation of the true color of the stamp.
Like with printing methods, it’s often safest to compare 2 stamps of the same era to make a color determination.
Expertizing #
Failing a proper ID by yourself, the best way to ensure you know which stamp you have is by having it expertized.
This means to have a knowledgeable stamp collector/dealer look at the stamp and try to give a positive ID.
You may be able to have a local dealer do this for you, and they may or may not charge for the service.
But the most common way of being expertized is to send the stamp off to one of the various stamp expertizing services.
An article listing the most common such services in the US can be found here; if you live in another country then you may want to find a similar such service more local to you.
A caveat to this is that these services will cost money, generally the more expensive they determine the stamp to be the more they will charge.
This can often be a big impact to what you may want to sell the stamp for, possibly even more than the full sale cost of the stamp.
This applies even if you send a stamp and they determine it is a common stamp worth pennies.
So you want to be generally sure you have a valuable stamp that will sell for a good deal of money before having it expertized.
But at the same time, most serious collectors won’t buy a stamp that could be mis-identified without a certificate verifying its authenticity.