Identification
How to Identify a Watermark on a Stamp
A watermark is a faint design pressed into the paper during manufacture, visible when the stamp is held to the light. It matters because the same stamp design can exist with different watermarks, which can make it a different, and differently valued, stamp. The simplest way to see a watermark is to hold the stamp to the light; if that does not reveal it, lay the stamp face down in a watermark tray and add a little watermark fluid.
At a glance
What a watermark is, and why it matters
A watermark is a pattern, often a crown, letters or a device, deliberately worked into the paper as it is made, so that it appears slightly thinner where the design sits. It is not printed, and it is usually invisible in normal light.
It matters because two stamps of the same design can carry different watermarks from different printings, and that difference can change which stamp it is and what it is worth. Our glossary entry on watermarks gives the background.
How to see a watermark, step by step
Hold the stamp to the light.
Turn it face down against a bright light or window. Often the watermark shows as a faint pattern.
Use a dark background.
Lay the stamp face down on a black surface or in a black watermark tray, which makes a faint watermark easier to see.
Add watermark fluid if needed.
A few drops of watermark fluid in the tray darken the paper briefly and reveal the watermark, then evaporate without harm to most stamps.
Try a watermark detector.
For difficult cases, an electronic watermark detector can show the design without fluid.
Note its position.
The watermark's orientation, upright, sideways or inverted, can itself be a recognised variety.
A word of caution
Fluid is not safe on every stamp
Watermark fluid is safe on most stamps, but not all. Some inks, particularly certain reds and aniline colours, can run or be affected by fluid, and used stamps on poor paper can be delicate. If a stamp is potentially valuable, or you are unsure, do not risk fluid; have it examined by someone experienced instead. Our quality and grading standards explain the care we take with every stamp.
Watermarks and identification
A watermark is one of the technical features that pins down a stamp's exact identity, alongside its perforation. Together they often decide which catalogue number, and which value, a stamp carries. Our guides to measuring perforations and identifying a stamp set out the wider method, and reading an SG number explains how the catalogue records these differences.
Frequently asked questions
Hold the stamp face down to the light. If the watermark does not show, lay it face down on a black surface or tray and add a little watermark fluid, which reveals the design and then evaporates.
Because the same stamp design can exist with different watermarks from different printings, which can make it a different stamp with a different value.
It is safe on most stamps, but some inks can run, and delicate stamps need care. If a stamp may be valuable, or you are unsure, have it examined rather than risk fluid.
The orientation, upright, sideways or inverted, can be a recognised variety in its own right, and is worth noting when you identify a stamp.
Founder and stamp dealerLast updated June 2026