Stamp Authentication and Grading [Magnification Guide]
Grading a stamp means judging centering, margins, perforations, gum, and freedom from faults; authenticating means confirming the paper, watermark, perforation gauge, and printing method match the genuine issue. Both depend on looking at details between 5x and 20x under good light. A consistent inspection routine and a few photos catch most problems, and anything valuable should still go to a recognized expertizing service.
Two questions, one set of tools
When a stamp arrives, you are asking two things. Is it what it claims to be, and what condition is it in. The first is authentication: does the paper, watermark, perforation, and printing match the genuine issue, and has it been altered. The second is grading: how well centered it is, how intact the perforations are, what the gum looks like, and whether it has faults. Both are answered by looking closely in a consistent order.
This guide gives you that order. It assumes a 10x loupe or a phone magnifier, stamp tongs, a perforation gauge, watermark fluid with a black tray, and a lamp you can move. Our toolkit article covers the equipment in more detail.
Step 1: Centering and margins at low power
Centering is the relationship of the design to the perforations. A perfectly centered stamp has equal margins on all four sides. Look at 3x to 5x so the whole stamp fills your view, and compare top with bottom and left with right. Grading terms run roughly from Average or Fine, where the design is noticeably off toward one side, through Very Fine, where margins are close to balanced, to Extremely Fine and Superb, where they are essentially equal. Grading services use numerical scales that refine these terms, and their published standards are worth reading.
A phone photo taken straight down helps here. In LoupeLens, frame the stamp at about 4x, hold the phone parallel to it, tap to focus, and capture. In the still image it is much easier to compare margin widths honestly than while holding a loupe, and you can measure them against a ruler in the same frame.
Step 2: Perforations at 10x
Move to 10x and travel around the edge. You are looking for:
- Short or pulled perfs. Teeth that are shorter than their neighbors or missing. These lower the grade.
- Reperforation. A straight edge or a damaged side that has been given new holes. Signs include holes that are too regular compared with the other sides, teeth that look freshly cut with no wear, or a gauge that does not match the other sides.
- Gauge. Lay the stamp on the gauge, photograph it at 5x with LoupeLens or the camera, and confirm the measurement on the still image. A gauge that does not match the catalog for that issue means a different printing or a problem.
Compare all four sides. Genuine perforations from one machine are consistent all the way around.
Step 3: Paper and faults under raking light
Set the lamp low and to one side so light skims across the surface, and look at 5x to 10x. Then turn the stamp over and repeat. Raking light reveals:
- Thins. Areas where paper has been lost, often from hinge removal. They appear as faint depressions from the back and as brighter patches under transmitted light.
- Creases and bends. Even pressed-out creases show as a line under raking light.
- Repairs. Filled thins, rebacked stamps, and closed tears. Look for a change in surface texture, a slight ridge, or fibers that run in a different direction.
Finish with watermark fluid in the black tray. The watermark must match the catalog for that issue. Fluid also shows thins and repairs clearly, since they soak differently from sound paper.
Step 4: Gum
For unused stamps, gum condition is a large part of the grade and one of the most common areas of deception. At 10x on the back:
- Original gum tends to have the characteristic texture and color for that issue, with aging consistent with the paper. Hinge remnants or hinge marks reduce the grade but do not mean the gum is fake.
- Regummed stamps often show gum that has flowed onto the perforation tips, a glossy or uniform look that does not match the era, or gum that fills the small fibers at the tooth ends. Genuine gum was applied before perforating, so the tips are usually clean.
- Disturbed gum shows fingerprints, glazing, or areas where a hinge was soaked off.
Run a fingertip very lightly along the perf tips of a stamp you know is original gum, then the one in question, without touching the design. Regummed tips often feel slightly stiff. Confirm what you feel by looking at 20x.
Step 5: Printing method at 15x to 20x
This is where authentication becomes specific. Many forgeries were produced by a different method from the original, and at 15x to 20x the difference is visible.
| Method | How it looks at 15x to 20x | Typical use |
|---|---|---|
| Engraved (intaglio) | Ink stands slightly raised in fine lines; lines may be felt; sharp edges | Many classic issues |
| Typographed (letterpress) | Ink pressed into paper, slight squash at edges of lines; sometimes impression visible on back | Many 19th and early 20th century issues |
| Lithographed | Flat ink, soft edges, no relief; lines made of tiny dots or smooth tone | Many forgeries, some genuine issues |
| Photogravure | Fine screen of cells or dots visible across the image | 20th century issues |
If the catalog says engraved and what you see at 20x is flat with dotted tone, the stamp is not what it claims. The reverse also happens. Compare the detail against a known genuine example photographed at the same zoom. This is a strength of using a phone: you can keep a reference album of genuine printing detail and lay the new photo beside it.
Step 6: Cancels and overprints
Used stamps with scarce cancellations, and any stamp with an overprint or surcharge, attract forgers. At 15x, genuine ink of the period sits in the paper fibers with a consistent look, while later additions may sit on top, have a different sheen, or show dot patterns from modern printing. Overprint letter shapes, spacing, and position relative to the design should match reference examples exactly. Small differences in a single letter are a common tell.
Putting it together and knowing when to stop
Write down what you found at each step before you form a conclusion. A stamp with perfect centering, clean perfs, and original gum but a watermark that does not match is not a high-grade example of the issue you thought it was. It is a different issue, or a forgery.
For anything with real value, send it to a recognized expertizing service. A certificate protects you when you buy and is expected when you sell. Your own inspection is what tells you whether a stamp is worth the fee and what questions to ask. Photograph the stamp front and back before sending it, at 4x overall and 15x on any area of concern, so you have a record of its condition as it left you.
The routine above takes a few minutes per stamp once it becomes habit, and it is the same routine whether the stamp is worth a little or a lot. Good light, patience, and a consistent order catch far more problems than expensive equipment does. For technique on getting sharp, honest close-ups, see our guide to photographing small objects.
Frequently asked questions
What magnification is used for stamp grading?
Centering and overall appearance are judged at 3x to 5x. Perforations, gum, and paper faults are checked at 10x. Printing method and overprint details need 15x to 20x. Higher power rarely adds useful information on a flat stamp.
How can I tell if a stamp has been regummed?
Look at the back at 10x to 20x. Regummed stamps often have gum flowing onto the perforation tips, a finish that does not match the era, or gum filling the fibers at the tooth ends. Genuine gum was applied before perforating, so the tips are usually clean. Compare with a stamp you know to be original.
How do I check a stamp for thins?
Hold a lamp low and to one side so light skims across the back of the stamp and look at 5x to 10x; thins appear as faint depressions. Transmitted light shows them as brighter patches, and watermark fluid in a black tray shows them clearly because thinned paper soaks differently.
Do I still need an expertizing certificate if I inspect carefully?
For any stamp of significant value, yes. Your inspection tells you whether the stamp is worth the fee and what to ask about. A certificate from a recognized service is what buyers and auction houses expect, and it protects you against a wrong purchase.
Can I tell a forgery from the printing method?
Often. At 15x to 20x, engraved stamps show raised ink in fine lines, typographed stamps show ink pressed into the paper, and lithographed stamps look flat with soft edges or dot patterns. If the method you see does not match the catalog for that issue, the stamp deserves serious doubt.