What Counts as an Error Coin?

 

What Counts as an Error Coin?

Most coin collectors understand the concept of an error coin, but reliably identifying a genuine error can be easier said than done. Post-mint damage (PMD), damage or defacement that happens to a coin once it leaves the U.S. Mint, can sometimes look like a real error. Only coins with errors that happened during the minting process are considered rare or valuable, so learning how to spot the real errors from fakes can help collectors avoid making a costly mistake. 

To complicate things a bit more, even some coins that appear to be genuine errors may not count for collectors’ purposes. This is because all mints use acceptable manufacturing tolerances, which are acceptable deviations from the normal features that each coin is supposed to have. If a coin has only a very minimal misalignment, for example, it may not count as an error if that misalignment falls within the acceptable tolerance range. 

So, which coins actually count as error coins? On this page, we’ll walk readers through some of the most popular coin error types, how to identify genuine errors, and how to avoid fake or counterfeit error coins. 

Post-Mint Damage (PMD) Explained

To error coin collectors, post-mint damage should be a familiar term. A number of things may happen throughout a coin’s lifespan to make it appear deformed or irregular. Sometimes, unscrupulous collectors deliberately alter the appearance of their coins to make them look like genuine mint-made errors. Simply put, post-mint damage refers to coins that have been damaged after they leave the mint, rather than during the minting process.

Spotting the difference between post-mint damage and genuine mint-made errors can be tricky and requires collectors to understand how errors actually occur during the minting process. If you’re a new collector dealing with a malformed coin, the best way to verify that you’re handling a genuine error is to seek the advice of an experienced error coin dealer or numismatist.

Collectors who don’t want to consult an expert should compare their coin to documented specimens of the same error type. By cross-referencing the features of their coin against known errors of the same type and degree, it is possible to get a pretty good idea of whether a coin features a genuine mint-made error or post-mint damage.

Tolerance Levels for Minting Errors

Once a collector confirms that their coin has a genuine error rather than post-mint damage, it’s time to take a look at error tolerance levels. Tolerance levels for errors are usually either set by reputable grading companies, such as NGC or PCGS, or by the U.S. Mint. 

Consider rotated error coins as an example. Most rare coin experts only consider coins with a rotation of 15% or more to be valuable errors. Coins with a rotation of less than 8% are typically considered to be within the U.S. Mint’s manufacturing tolerance, meaning that they have little value as error coins. 

Of course, tolerance levels can vary from coin to coin. The modern U.S. Mint is far more precise than it was 100 years ago, so it is harder to find a coin with a small error today than it was in the early 20th century. A qualified rare coin expert should be able to tell collectors if their coin errors fall within the acceptable manufacturing tolerance. 

Common Types of Error Coins

One of the easiest ways to verify that an error coin features a genuine error is to develop a better understanding of the major errors that can occur during the minting process. Oftentimes, coins with post-mint damage will present improbable errors that are fundamentally inconsistent with genuine errors that can occur during the minting process. 

Below, we’re going to take a closer look at the three main mint-made error categories, as well as some of the most commonly collected error coin types that fall into these categories.

Planchet Errors

The creation of the planchet is one of the first steps in the minting process. A planchet is a plain, thin disk of metal that looks like a coin without designs or texture. To create planchets, the U.S. Mint takes a large strip of metal and cuts it into smaller, circular disks. Unsurprisingly, errors can occur at this step of the minting process.

Two of the most common planchet errors are clipped planchets and lamination flaws.

Clipped Planchets

Clipped planchets happen when the machine that cuts planchets out of strips of metal malfunctions and accidentally punches a blank that overlaps with a previously punched blank. The result looks like a coin that is missing a chunk, and clipped planchet errors can vary in severity and obviousness.

Like many other errors, genuine clipped planchets can be very valuable to collectors. The best way to verify that a clipped planchet coin is genuine is to verify the Blakesley Effect. The Blakesley Effect states that clipped planchet coins should feature absent or very weak rims opposite to the point where the clip supposedly occurred. This effect happens because the clipped planchet creates an uneven flow of metal during the striking process. 

Lamination Flaws

Unlike other common mint-made errors, lamination errors may not be evident until weeks, months, or years after a coin has been struck. On coins with lamination errors, the outside layers of metal may peel or “flake” off over time. Lamination errors are typically caused by mistakes during the minting process. More specifically, a lamination error can occur when grease, gases, debris, or other materials interfere with the mixed metal that composes the coin. 

Over time, a lamination flaw coin’s imperfections create weaknesses on its surface, which leads to the peeling effect collectors observe over time. It can be difficult to delineate a genuine lamination flaw coin from a coin with post-mint damage, since peeling the outer layer off of a coin isn’t exactly a technically difficult task.

Aside from asking for help from another coin collector, dealer, or numismatist, collectors can verify the authenticity of a lamination flaw on their coins by ruling out evidence of tampering or interference. In particular, we recommend taking a close look at the coin under a microscope to assess whether or not the coin appears to have been chemically or physically altered using pliers.

Die Errors

Die errors are some of the most popular coin error types. The die is a thick piece of metal that mints use to strike a coin’s designs onto the blank pieces of metal we call planchets or blanks. Because dies are used over and over to strike hundreds of thousands of coins, they can sometimes malfunction, creating rare and valuable errors on coins. 

The two most popular (and common) die errors are doubled dies and misaligned dies.

Doubled Dies

Doubled dies are probably the most iconic errors seen on United States coins. No matter how experienced you are at collecting, you’ve likely seen the 1955 doubled die penny, which is one of the most recognizable and spectacular error coins in U.S. Mint history. 

A doubled die error occurs when a coin is struck twice by its die instead of just once. The result is a doubling effect that often looks like a shadow behind certain parts of the coin. The best way to confirm that a coin features a genuine doubled die error is to compare it to known specimens. Doubling can occur on hundreds or thousands of coins before it is noticed, and coin grading companies like PCGS regularly publish photographs of known doubled die errors. 

Misaligned Dies

Sometimes, one side of a coin may appear misaligned or off-center, while the other appears perfect. This is known as a misaligned die error, and this type of error coin is popular among rare coin collectors. Misaligned dies occur when one of the two dies (one for the obverse and another for the reverse) is incorrectly lined up when striking the coin.

To verify that a coin features the misaligned die error, collectors should take a close look at both sides of the coin. On a true misalignment, one side of the coin should be perfectly aligned, but the other should be improperly aligned. This error occurs when the hammer die striking the obverse is misaligned with the anvil die, which strikes the design on the reverse of the coin. In other words, only one side of the coin should be misaligned for it to qualify as a misaligned die error.

Strike Errors

Other errors can occur during the striking phase, one of the last steps in the process of minting a coin. Off-center strikes and brockage errors are two of the most common errors that can occur during the striking part of the U.S. Mint’s coin production process. These coins are relatively rare, but they’re also sometimes counterfeited by unscrupulous coin dealers or collectors.

Off-Center Strikes

If a planchet is not properly centered while it is being struck by the die, this can result in an error known as an off-center strike. Off-center strike coins are relatively easy to spot, and many of them are spectacular and obvious in nature. A coin with an off-center strike will include only part of its intended design, with the rest of the coin appearing to be a blank planchet.

Off-center strike coins are sometimes confused with misaligned die errors. On an off-center strike, a coin will be misaligned and off-center on both sides, since this error is caused by the coin not being centered between the hammer and anvil dies. On a misaligned die, however, the error is caused by one of these two dies being misaligned, resulting in an off-center strike on only one of two sides.

Brockage Errors

Brockage errors are some of the most interesting error coins accidentally produced by the U.S. Mint. Brockage error coins appear to have part or all of one side’s designs struck onto the opposite side. Brockage errors occur when a coin that has already been minted sticks to the die, striking subsequent coins until it is eventually removed by mint workers. 

While brockage errors are easy to spot, verifying that they are legitimate error coins can be tricky. Fake brockage coins are often made using vice grips. Someone who makes a fake brockage error coin may take two coins from the same year and, flipping one over, apply extreme pressure to them using vice grips or another tool. The coins will then appear to have the incorrect designs stamped onto their obverses or reverses.

Brockage errors typically only impact one side of a coin, rather than both. When someone uses tools to fake a brockage error, they’ll often leave clear marks on the other side of the coin, which can give it away as a counterfeit error. When in doubt, we recommend reaching out to an expert.

Another telltale sign of a fake brockage error coin is if the coin appears to feature the image of another, unrelated coin on its obverse or reverse. While this error type, known as a mule coin, does occasionally occur, it is extremely uncommon.

How to Confirm a Legitimate Mint-Made Error

To confirm that an error coin features a legitimate mint-made error, collectors should do two main things:

1. Rule out the possibility of post-mint damage causing the appearance of an error.
2. Verify that the coin’s error is outside of the acceptable manufacturing tolerance.

Collectors who are unsure whether their coin is a legitimate mint-made error should reach out an an expert on the subject, such as a rare coin dealer or a respected numismatist. Coin grading companies like NGC and PCGS can also authenticate error coins, although this process can be costly, especially if the coin in question is rare or especially valuable.

Final Thoughts: What Counts as an Error Coin?

Coins can change hands thousands of times throughout their lifespan. As a result, many coins appear to have abnormal features that might be interpreted as mint-made errors. However, not all strange-looking U.S. coins are error coins. Some coins marketed as error coins were actually defaced accidentally or intentionally, and others feature errors that are within the acceptable tolerance levels. 

Learning to consistently identify genuine error coins is a skill that can take years or decades to learn. Over time, collectors like yourself can use visual clues, close examination, and knowledge of how error coins are created to separate the real errors from the fakes.

You might also be interested in:

• What are Mint-Made Error Coins?
• Collecting Brockage Error Coins
• What is the “In Cod We Trust” Quarter?