Error Stamps: How to Identify Stamp Errors and Varieties

8 min read

Every collector dreams of spotting a famous mistake in a box of ordinary stamps. It does happen — the stories behind the most famous ones are told in our article on famous stamp errors and rarities. But genuine errors are rare, and many stamps that look like errors are something else entirely. This guide explains the main types of error, how to check a stamp you suspect, and how to avoid being fooled.

Errors, Freaks and Oddities

Collectors often group unusual stamps under the label EFO: errors, freaks and oddities. The distinction matters, because it largely decides what a stamp is worth.

Errors are major production mistakes that affect a stamp completely and consistently — a centre printed upside down, a colour left out entirely, perforations missing altogether. A true error is usually listed in catalogues and can be very valuable.
Freaks are one-off accidents in production: perforations badly shifted, a smear of ink, a fold in the paper before printing. Each is unique, and they are fun to collect, but most are worth only a modest premium.
Oddities and varieties include constant flaws — a mark on the printing plate that appears on the same position of every sheet — and other recurring differences. Well-known varieties are listed in specialised catalogues.

The Main Types of Error

Inverts

Part of the design is printed upside down relative to the rest. This happens with stamps printed in more than one pass, when a sheet is fed into the press the wrong way round for the second colour. The US Inverted Jenny of 1918 is the most famous invert. An overprint or surcharge applied upside down is a related error, and generally easier to find than an inverted centre.

Missing Colours

One or more colours are absent — for example a design printed without its gold, or missing the colour that carries the denomination. Modern multicolour stamps are the usual source. Missing colours are among the most commonly faked errors (see below).

Imperforates

Stamps that should have perforations but don’t. A fully imperforate stamp lacks perforations on every side; an imperforate between pair is perforated around the outside but missing the perforations between the two stamps. Always collect imperforate errors in pairs or larger — a single imperforate stamp can easily be faked by trimming the perforations off a normal one.

Double Prints

Part or all of the design is printed twice, either slightly offset or one on top of the other. Don’t confuse this with a blurred or “slurred” print caused by movement in the press, which is a freak.

Wrong Colour

A stamp printed in the colour intended for a different value, such as Sweden’s famous yellow 3 skilling of 1855.

Watermark Errors

A stamp printed on paper with the wrong watermark, or with the watermark inverted, reversed or sideways when it should be upright. These are invisible to the naked eye, so they are still found in collections today. See our guide to watermark detection.

Other Errors

Tête-bêche pairs — two stamps printed upside down relative to each other, sometimes by error, sometimes deliberately.
Albino impressions — an albino is a colourless embossed impression where the ink failed to print.
Missing phosphor or tagging — many modern stamps carry phosphor bands or tagging that glows under ultraviolet light for automatic mail sorting. Stamps where it is missing are collected as errors, and you need a UV lamp to see them.

How to Check a Stamp You Suspect

Compare it with a normal copy. Put the suspect stamp next to an ordinary example. Many “errors” turn out to be normal on closer comparison.
Use a magnifier. Look at the edges of colours, the perforation holes and the paper surface.
Measure the perforations. A perforation gauge will show whether perforations have been trimmed or added. See how to use a perforation gauge.
Check the margins. An imperforate with margins narrower than a normal stamp’s perforated margins has probably been trimmed.
Use a UV lamp for tagging and phosphor errors, and to reveal some repairs and chemical changes.
Look it up. Check whether the error is listed in a specialised catalogue for the country. Listed errors have a known history; unlisted ones need more care.

Fakes and Look-Alikes

Because errors can be valuable, they attract forgers. The commonest traps:

Changelings. Stamps whose colour has been altered by sunlight, heat or chemicals. A “missing colour” error can be manufactured by removing a colour chemically. Compare the paper and the remaining colours carefully with a normal copy.
Trimmed perforations. A normal stamp cut down to pass as an imperforate. This is why imperforates should be collected in pairs.
Faked overprints. Inverted or double overprints are relatively easy to add after the fact. Valuable overprint errors need expert examination.
Printer’s waste. Spoiled sheets meant for destruction sometimes escape the printing works. They can show striking “errors” but were never issued, and collectors value them far less than genuine errors.
Deliberate “errors”. Some apparent errors were produced on purpose. In the 1930s, US Postmaster General James Farley gave imperforate and ungummed sheets to officials and friends; after public complaint, the stamps were reissued for general sale. These “Farley’s Follies” look like errors but are common.

A proof — a trial printing made before production — can also be mistaken for an error, especially in an unusual colour.

Found Something? What to Do Next

Don’t soak it, clean it or remove it from its cover. Handle it with tongs and keep it in a protective mount or stock card.
Keep it with its neighbours. If the error is part of a pair, block or sheet, keep it intact. Multiples are worth more and are easier to authenticate.
Record where it came from. Provenance helps with authentication.
Get an expert opinion before buying or selling. For any error that may be valuable, an expert certificate from a recognised committee is essential. Our guide to finding the value of stamps explains how.

Are Error Stamps Worth Money?

Some are worth a great deal: the most famous errors are among the most valuable objects in philately. But value depends on how many examples exist, how well known the error is and the stamp’s condition. Most freaks and minor varieties sell for a modest premium over the normal stamp. Collect them because they are fascinating — and if you find something special, take your time and get it checked.

Glossary terms used in this guide

Albino — An albino is a colourless, inkless impression of a stamp design — usually embossed — caused when the printing or embossing process runs without ink reaching the paper.
Error — A stamp error is a major, unintended mistake in production — such as an inverted centre, a missing colour, missing perforations or the wrong paper — that sets a stamp apart from the normal issue.
Forgery — A forgery is an imitation of a genuine stamp, overprint or postmark made to deceive — either the post office, to avoid paying postage, or collectors, to sell a copy as genuine.
Imperforate — An imperforate stamp has no perforations and must be cut apart with scissors; imperforates were normal for the earliest issues and are errors when a normally perforated stamp is found without perforations.
Invert — An invert is a stamp error in which part of the design — such as the centre vignette, frame or overprint — is printed upside down relative to the rest of the stamp.
Overprint — An overprint is text or a design printed on top of an existing stamp, usually to change its country, purpose, or validity.
Perforation — Perforation is the series of small holes punched between stamps to allow easy separation.
Proof — A proof is a trial impression of a stamp design taken from the die or printing plate before or during production, to check the engraving, colour or plate before stamps are issued.
Surcharge — A surcharge is a specific type of overprint that changes the face value of a stamp.
Tête-bêche — Tête-bêche describes a pair of joined stamps in which one stamp is printed upside down or sideways relative to the other.
Variety — A variety is a stamp that differs in a recognisable, usually minor, way from the normal version — such as a shade, plate flaw, re-entry, paper or perforation difference.
Watermark — A watermark is a design embedded into stamp paper during manufacture, used to identify and authenticate stamps.