The term postage stamp error is used to describe any glitch in the intended appearance of the stamp caused by a printing failure. It can be anything from the wrong use of colors to misplaced, inverted or missing design elements. Since postal administrations strictly control every stage of the printing process, most design inconsistencies are addressed before the stamps go on sale. As a rule, only a few dozen copies featuring a particular error ever reach the public – an oversight that takes place once in several decades. Stamps with printing errors are strongly coveted by collectors, some being valued thousands of times higher than their nominal price.


The philatelic value of an error stamp is defined by its visual appeal and relative scarcity. The more visible the printing mistake is the more chances are for the stamp to sell big. If the error is rare and appears only on several copies, the stamp value gets another hike. Every new sample with the same kind of error that comes into sight diminishes the price you can potentially fetch for a faulty item. When another copy of the stamp previously considered unique is discovered, it usually sells considerably cheaper than the first one.

Learn more about the most common stamp error types explained below.

Missing color

Color-omitted error stamps have one or more colors missing. These errors usually occur when one stage of a multi-run printing process is skipped. The results range from eye-striking to practically invisible like partially missing colors that are counted as color omissions yet have little value. Missing color errors are more common for modern stamps, since older designs involved fewer colors and omissions were much easier to spot.

Color error

Faults of this type are caused by the use of wrong color ink in printing. If the design involves more than one color, particular shades are applied by a piece of hard rubber that inks only the portion of the plate intended to have that color. Each section is treated with separate pieces of rubber dipped in the ink of corresponding color. The process goes on until all parts of the stamp are inked according to the pattern. If the printing machine is charged with the ink of wrong color, the stamp ends up featuring a color error.

Color shift

One of the most widespread types of color stamp errors is color shift. This interesting effect can be seen when one or several printing plates are out of register with other plates. As a result, overlapping colors create an appearance reminiscent of a double impression (see below). Unlike the latter, though, the alleged second impression actually turns out to be a different color applied above the intended design, since the stamp passes multiple presses for each color. Depending on the space between the plates, color shifts can be immediately visible or slightly noticeable.

Double impression (Double transfer)

Double impression, also called double transfer, is a stamp showing two impressions of the same design. This happens when the stamp is being repeatedly passed through a printing machine. Depending on how the sheet is placed the second time, the extra impression may be straight, mirrored or even reversed. It can show a full impression or reveal only part of the original design. The same concerns colors, some of which may be omitted during the second phase of printing.

Invert error

This type of error occurs when one or several design elements of a postage stamp are printed upside down. In most cases, it happens when repeatedly passing a stamp sheet through the printing press to get a multicolored impression. During this process, a printing plant worker can easily insert a half-ready sheet the wrong way around and thus cause an invert.

There are two basic variations of this error: inverted center and inverted frame. While the first comes with an inverted central piece, the second only affects the frame orientation. The latter, of course, is less distinctive and may easily be overlooked.

Inverted Jenny, 1918, U.S.

The most widely known instance of invert error is the Inverted Jenny, a postwar aviation stamp depicting Curtiss JN-4 in rose and blue. When the design went on sale back in 1918, the image of the biplane appeared upside down on over one hundred stamps, but only pane was discovered so far. That made the stamp highly valuable for collectors. Once worth around a dollar, a plate block of four Inverted Jennies was recently auctioned for a record $2.97 million in New York – the highest price a U.S. stamp item was ever able to fetch.

Inverted Swan, 1855, Australia

Talking about frame inverts, one should definitely recall the Inverted Swan issued in 1855 in Western Australia. The error occurred during the replacement of two damaged impressions. While one of the frames was tilted, the other was deliberately reprinted upside down. Although nearly four hundreds of Inverted Swans went on sale, the flaw was discovered many years later, with only 15 complete copies left nowadays. The most valuable copy was auctioned for $80,000.

Buenos Aires In Ps, 1859, Brazil

Translated from French as “head to tail,” tete beche is a pair of joined stamps, one of which is printed upside down. The error may occur on a vertical or horizontal pair, but not triangular, which is tete beche by default.

During booklet production, a large printing plate is typically used to create multiple pages of stamps, which can result in inverted pairs. Because individual pages are thoroughly inspected before being bound into a booklet, tete beches are extremely rare.

One of the most notable and expensive tete beche pairs is Buenos Aires 1859 In Ps. The Barquitos series named after the ships on the central image has always been viewed as a great rarity, with even regularly oriented stamps selling for up to $3,000 apiece. Initially priced just 1 peso, the only copy discovered is now worth $575,000.

Value error (Substituted subject)

When the stamp comes with a wrong denomination, we have a value error at hand. It can be a high-value denomination on a design meant for lower values or vise versa. Value errors typically occur because of confusingly similar designs or an excessive variety of denominations.

Treskilling Yellow, 1855, Sweden

The most famous example of substituted value is the Treskilling Yellow, one of the first stamps even printed in Sweden. The series depicting the Swedish coat of arms included denominations from 3 to 24 Swedish skillings, each associated with a specific color. Instead of the blue-green paper intended for the three skilling design, a set of stamps that saw the light of the day in 1855 was printed on the yellow-orange paper used for the eight skilling variety. Although the error is supposed to exist in multiple instances, only one copy of the Three Skilling Banco was found so far. Two decades ago, it was sold for $2.3 million.

Baden 9 Kreuzer, 1851, Germany

A similar story happened to the Baden 9 Kreuzer stamp issued in 1851 by the historical German state of Baden. Instead of pink, the stamp was printed in green color intended for a cheaper 6 Kreuzer denomination. Only four copies of this error that got into circulation have ever been discovered. The only unused copy with nearly full original gum was sold for 1,314,500 euro.

Offset

Classified as a minor mistake, offset is still a highly sought after error that increases the value of the stamp. As you can see on the picture, offset error stamps have a normal impression on the front and a reserved impression on the back. This happens when a sheet of paper is skipped while being passed through the press. As a consequence, the ink meant for one stamp sheet is applied to another, creating an offset impression on the gum side.

Overprinting errors

Inverted overprint

Overprint is an extra layer of text or graphics applied to the surface of the stamp after printing. While overprints are mostly used for administrative purposes, they can also act as a commemorative inscription to make the stamp more appealing to the public. Since adding an overprint is up to postal offices where production control is way weaker than in printing houses, overprint errors are very widespread. Nevertheless, they can raise the value of the stamp manyfold.

Overprinting errors can come in the form of:

1) Missing overprint. A total omission of overprint regularly found on other stamps of the kind.

2) Inverted overprint. Application of the overprint upside down related to its normal position on other stamps.

3) Wrong overprint. The use of an overprint intended for another stamp.

Watermark error

In stamp printing industry, watermarks are used to give the stamp a distinctive appearance and prevent counterfeiting. However, this process isn’t glitchless. Missing and inverted watermarks are common stamp errors, although they may take several minutes of close inspection to spot.

KGV Penny Red, 1914, Australia

Among recent examples, one should definitely name the one-dollar Penny Red, an Australian stamp of the 1914 issue depicting King George V. A faulted copy with a sideways watermark was discovered last year at a Scottish stamp fair and appraised at $100,000 after failing to sell at eBay for 99 cents.

Imperforate error

This error can be recognized by missing perforations on one or several sides of the stamp. For those unfamiliar with the concept, perforations are rows of small holes separating individual stamps on a printing sheet or roll and thus making it easier to tear them off. Depending on the perforating method, different stamps have a different number of teeth that also happen to take different shapes. This is one of the parameters impacting the final value of the stamp.

Most often, imperforate errors occur in coil stamps, since coil printing is mostly automated and the staff has no opportunity to detect a flaw. Modern coil stamps are born from a roll of blank paper put through intricate printing and perforating machinery. At the end, a perforated sheet is cut into strips, rolled and placed in plastic bubbles that go on sale. Once sealed inside, coil stamps can’t be inspected for conformity with the perforation pattern.

Imperforate coils

Encountering an imperforate error on a sheet stamp is a much rarer event. Unlike their coil counterparts, sheet stamps aren’t packaged before reaching the public, which makes it easier for printing house workers to determine inconsistencies. Therefore sheet stamps with misperfs have a considerably higher value and are strongly coveted by collectors.

Imperforate between

Horizontally imperforate

Vertically imperforate

There are several variations of imperforate errors described by special terms. For instance, “imperforate between” means that perforations between some stamps are missing, but exterior sides are perforated all right. “Horizontally imperforate” means that the sheet comes without horizontal perforations, but does have vertical ones. And vise versa, “vertically imperforate” stamps lack vertical holes while having normal horizontal perfs.

Aside from errors, professional philatelists also distinguish freaks and oddities.

Freaks are one-time mishaps that take place during the printing process. This group of printing flaws includes inking and perforation glitches, miscuts and alien objects like dust particles, hairs, pieces of food or insects accidentally embedded underneath the ink. They make the stamp unusable, but aren’t considered to be value-boosting flaws like major errors described above. In general, freaks have a negative philatelic status and are rather undesirable. However, most visually striking samples can bring their owner a few extra dollars.

Inking errors

Some minor flaws can also appear during the inking stage. Basically, stamps with inking defects fall into three types:

1) Overinking. An excessive amount of ink being applied to the stamp to create a very heavy impression, sometimes to the extent of making the design unrecognizable. This happens when a plate is charged with too much ink.

2) Underinking. The opposite of overinking that results in a very faint design lacking color and distinction. The reason is too little ink on a plate, usually at the end of a press run.

3) Ink smears (Blobs). Sometimes uneven concentration of ink on the plate leads to the appearance of blobs on the stamp surface. Unlike the first two error types, smears affect only part of the design and are also much rarer than regular overinking or underinking.

4) Albino. Sometimes the inking stage is skipped entirely, resulting in a blank impression known as albino error. Basically, it’s simply an engraved image with no color applied.

Perforation shift (Misperforation)

Similar to imperforate error, perforation shifts refer to inappropriate puncturing of the stamp sheet. They result from stamp misalignment with the perforating equipment when the raw of holes goes through the body of the stamp. The value of a misperforated stamp depends on how drastic the shift is.

Wild perforation (Foldover)

This type of error occurs when a corner of a stamp sheet is accidentally folded over before being passed through the perforating machine. As a result, the folded part comes out blank and punctured all over to form a random perforation pattern. Sometimes one or more of the stamps are affected too, as the impression is applied to the back side of the folded paper. In cases like this, the design emerges partly unprinted, usually with diamond-shaped blank patches in the place of the foldover.

Gum error

Stamps with a gum error are gummed on the wrong side or on both sides at once. As a result, the stamp has a sticky face and a flat back, which automatically renders it invalid.

Originally, gum was applied manually between printing and perforating, since the paper had to be damp to get a good impression. The process is now fully automated, with all stamps being printed on pregummed paper. Gum errors occur when the sheet is being accidentally passed through the printing machine the wrong side down.

Miscut

Miscuts are characterized by a shift of the central image that can be very distinctive or take just a few millimeters. Sometimes the impression extends beyond the frame, with just half or less of it visible and a portion of an adjacent design coming in sight.

Errors like this happen when the stamp sheet is misaligned with the cutting machine. As a consequence, perforations don’t coincide with the stamp borders creating a shift across the entire plate.

Most frequently, miscuts take place in coil stamp production, when the lower part of the design at the top of the stamp adjoins the upper portion of the same image below.

Oddities

An oddity is a design inconsistency that doesn’t affect the usability of the stamp yet has a distinctive appearance. Due to their uniqueness, oddities are impossible to classify or outline in any way. Small things like eyes above the head or two sets of shirt buttons can make the stamp more desirable for collectors and therefore more valuable. Since oddities vary from stamp to stamp and are not as obvious as errors and freaks, they are easy to skip and have to be looked out for.

If you think you may have discovered an error, freak or oddity on one of your stamps, get it authenticated and appraised at a reputable stamp dealer to find out its value.