The Truth About Stamp Expertizing: When It’s Worth It (and When It’s Not)
I was reading an article the other day about stamp grading and expertizing, and it was clear the author didn’t quite get it—especially when they started lumping computer grading and human expert opinion into the same bucket. As someone who was involved in developing grading technology back when this was all still new, I figured it was worth offering a more informed take. We’ve just passed the 25-year mark since numeric stamp grading became a thing when PSE (Professional Stamp Experts) was purchased by Collectors Universe early in the year 2000, and whether you love it or hate it, there’s no putting the genie back in the bottle.
Stamp collecting—philately, if you want to get fancy—is an endlessly fascinating hobby. With hundreds of thousands (or perhaps millions) of stamps issued worldwide since 1840, figuring out which ones are valuable and authentic can be tricky, even for seasoned collectors. A stamp that looks ordinary at first glance might be worth a fortune due to tiny differences in design, color, watermark, or perforation. That’s where expertizing comes in. But when is it actually worth it? And when is it just adding cost and complication? Let’s dig into what stamp expertizing really is—and when it pays off.
Why Expertizing Matters
Expertizing is the process of having professionals verify a stamp’s authenticity and condition. This is crucial because the difference between a genuine rarity and a well-made forgery can be nearly impossible to spot without specialized tools. Expertizing can turn a seemingly low-value stamp into a significant find—or expose a “great deal” as a cleverly disguised fake.
Organizations like Professional Stamp Experts (PSE), Philatelic Stamp Authentication and Grading (PSAG), the American Philatelic Society (APS), and the Philatelic Foundation (PF) offer expertizing services. They use high-powered magnifiers, UV lights, and even forensic imaging systems to detect alterations, repairs, and forgeries. When a stamp receives a certificate from a reputable expertizing body, collectors and investors can buy with confidence, knowing they’re getting what they paid for.
PSE, PSAG, and the PF offer additional grading services that go beyond authentication by assigning a numeric grade to each stamp. This grade reflects key factors such as centering, margins, color, and overall condition, giving collectors a clearer picture of the stamp’s quality. A higher grade can significantly enhance a stamp’s value, as well-centered, well-preserved examples are always in higher demand.
The Value of Grading—Even for Modern Stamps
Beyond authentication, expertizing also includes grading, which evaluates factors like centering, color, and overall condition. A high-grade stamp can fetch a significant premium, and for classic stamps—especially pre-1920 issues—this makes perfect sense. Older stamps weren’t produced with today’s precision, so well-centered, undamaged examples are genuinely scarce.
But that doesn’t mean modern stamp grading isn’t important. Even though modern stamps were produced in large quantities, finding a truly perfect example—one with razor-sharp centering, flawless gum, and no imperfections (faults)—is harder than you might think. Collectors who want the absolute best examples of every issue appreciate the ability to identify and own the finest specimens.
Computer Grading Programs
The real problem isn’t grading itself—it’s how some stamps are being graded. Some sellers have opted to use a software-based grading program, offering some collectors a quick and inexpensive way to “grade” their stamps at home using a scanner. While this might sound convenient, these programs have some serious flaws.
First, home scanners simply aren’t designed for the level of precision required for accurate stamp grading. Most consumer-grade scanners have a wide margin of error, meaning that a stamp measured in one spot on the scanner bed can receive a noticeably different grade when remeasured in another. This inconsistency makes it nearly impossible to get a reliable, repeatable grade using these programs.
Second, these automated systems tend to focus solely on centering, ignoring other crucial factors like paper quality, creases, small tears, or gum disturbances—all of which can dramatically affect a stamp’s value. A stamp might receive a high centering grade from software, but if it has a hidden fault, it’s worth far less than a truly flawless example graded by a professional.
This type of software can be a useful tool for prescreening stamps, but it should never be relied upon for final grading. Users need to understand the limitations of both the hardware and software to minimize errors. During my time at PSE, we extensively tested stamp grading programs across various scanner models and found that consumer-grade scanners simply don’t offer the precision needed for accurate grading. The results varied significantly based on the scanner’s quality and even where the stamp was placed on the scanner bed. In the end, we concluded that the human eye remains the most consistent and reliable grading method—a standard that PSE continues to uphold today.
Why Computer Grading Didn’t Work
One of the big misconceptions I keep seeing is the idea that computer grading is more accurate than the human eye. In theory, a computer should be able to measure things down to the pixel, with perfect consistency. But in practice, it just didn’t work that way.
A pixel measures 1/96th of an inch, or roughly 0.26 millimeters. That sounds pretty precise, but here’s the problem: computers don’t see the world the way we do. When we look at a stamp under magnification, we can clearly identify where one color ends and another begins. It’s a clean break, easy to measure. But when a computer scans that same stamp, it doesn’t see two distinct colors—it sees a gradual transition, and tries to assign an average shade to that area. That’s great if you’re just viewing the image on a screen, but it becomes a real issue when you’re trying to make precise measurements.
We ran into constant problems trying to tell the computer exactly where to place the measurement line. We tried to improve things by converting the color scans to black and white, then assigning anything above a certain saturation as one side of an edge, and everything below as the other. It helped a little, but we still couldn’t get the level of precision we needed. Ironically, even though we should have been able to get twice the accuracy of the human eye, we were actually getting about half.
The errors started stacking up fast—finding the edge of a perforation, the edge of the design, or compensating for something as minor as a speck of dust on the scanner bed could completely throw off the results. Photoshop touch-ups became the norm just to get usable data. In the end, the best precision we could consistently achieve was around 1/10th of a millimeter. That’s not terrible, but it’s a far cry from the 1/20th of a millimeter accuracy we were getting manually.
And here’s where it really matters: grading errors cut both ways—too generous or too harsh. That small margin of inaccuracy made computer grading less consistent than human grading. On lower-value stamps, that might not be a big deal. But when you’re talking about stamps where a tiny difference in grade can mean thousands of dollars, that margin becomes unacceptable. Consistency is everything at the high end, and that’s exactly where the computer struggled the most.
When Does Expertizing Make Sense?
Here’s the bottom line: expertizing is absolutely essential for valuable and potentially rare stamps. If a stamp’s authenticity is in question or if its condition significantly affects its value, a certification from a trusted expert can mean the difference between a $500 stamp and a $2,000 one.
Not every stamp needs to be expertized—if it’s easy to identify and there’s no doubt about what it is, a certificate won’t do much for it. But for rarer or more valuable stamps, expertizing is a great way to confirm authenticity and check for hidden flaws. On top of that, really exceptional stamps can be graded, and a higher grade can make a big difference in value. A well-centered, flawless stamp with a top grade will always stand out and be more desirable and valuable to collectors.
More and more, collectors are embracing stamps with slightly lower numeric grades—like VF-XF 85 or XF 90—not because they’re settling, but because they’re being practical. These grades still represent stamps with excellent centering and no faults, but they come at a far more accessible price than the top-tier Superb 98s or Gem 100s. With the shift away from traditional, in-person buying, collectors—especially those newer to the hobby—are relying on graded certificates for peace of mind. When you're not face-to-face with a dealer or holding the stamp in hand, your senses are at a disadvantage. Grading steps in to balance the equation, offering a consistent, trusted reference point.
Grading also gives collectors a way to define their own “level.” Some will insist on only the highest grades—Superb 98s and Gem 100s—while others are happy building outstanding collections with XF-Sup 95s, or sticking to solid, fault-free VF-XF 85s and XF 90s to stay within budget. All of these choices are valid, and importantly, all are respected in the market. When it comes time to sell, a graded collection—regardless of the specific level—sends a message: you cared, you collected with intent, and what you’ve assembled has real value that serious buyers will recognize.
For modern stamps, grading helps identify the best of the best. While some collectors are happy with any well-centered example, others want the absolute finest, and professional grading provides that assurance. The key is making sure the grading is done by a reputable service with the right technology—not an automated scanner that ignores key details.
As someone who worked at PSE in the early years to help develop much of the technology that is used today, I’ve seen firsthand how expertizing and grading have helped shape the stamp market. When done right, it protects collectors, ensures quality, and enhances the enjoyment of the hobby. Whether you’re collecting classic rarities or modern beauties, knowing when expertizing adds value—and when to be cautious of quick-fix solutions—will help the average collector make smarter choices.
