Generally speaking, there are two extremes in U.S. coin collecting. The first is to search for that Holy Grail coin in great condition, such as an 1856 gold Double Eagle that was minted in New Orleans and is graded AU-55, or a 1873 Morgan silver dollar, minted in San Francisco and graded MS-65.

People who love error coins are at the opposite end of the perfection spectrum, though they often pay top dollar for their treasured damaged goods. Errors are coins that didn't turn out quite as the mint intended, with clipped edges, overstruck dates, and quirky imperfections.

One of the many things that makes error coins so interesting is that they encourage the coin collector to become knowledgeable about the minting process itself, since all error coins are the result of something going awry at the mint.

At the top of the error pyramid are hub errors. The hub is the piece of hardened steel that is used to create a die, which is the metal punch that delivers a coin’s design onto a blank, or planchet. The design on the hub is the same as that on the coin, but the die is a mirror image, which means it transfers a correctly oriented image onto the final coin.

Until recent advances in minting technologies, it had taken two, three, and sometimes four strikes of a hub onto a heated die to successfully transfer the hub’s image. That left a lot of room for error, the most common of which occurs when the first and second strikes of a hub on a die are not perfectly aligned. In these cases, a doubled die is created, resulting in a coin whose elements repeat.

In rare cases, a double denomination can be created, such as in the case of the 11-cent denomination. Struck coins are sometimes transported from coining presses in bins that are later used to transport planchets. In this case, a bin full of struck dimes was reused to transport penny planchets. A few dimes that had become stuck at the bottom of a bin were struck again as cents along with all the planchets. The resulting 11-cent double denominations are larger than dimes but smaller than pennies. Coins that have the most detail are generally the most expensive, but collectors should mis-merit the value of a coin that's not perfectly round.

Another classic example of a doubled-die coin is the 1955 Lincoln Wheat penny, which some experts refer to as an error but others call a variety because so many of them made it into circulation. When the doubled die for this coin struck the obverse, or face, of the planchet, doubling occurred on the date and legend. As a result, the coin looks oddly out of focus...

Since the mistake was not caught until the coin was in circulation, no one knows for sure how many were made—just under 331 million Lincoln Wheats were minted that year, but only 15,000 doubled examples are known to exist. Whatever their number, the coin is credited with igniting an interest in error coins, as well as being a favorite target of forgers.

For collectors, only Lincoln Wheats with clearly defined doubling are considered valuable. For example, a coin with less pronounced doubling, known as a “poor man’s doubled die,” can be picked up for under a quarter, while coins whose doubling is clear and crisp sell for $1,000 and up.

Worn-out dies are also a problem. If the die is cracked, those cracks will also appear on a coin. Similarly, if a small section of the die has broken off, then a like-sized section of the coin will remain unstruck. This frequently happens along the edge of a coin and is referred to as a cud.

Even if the die is not compromised, many things can go wrong when it strikes a planchet. One relatively common occurrence is a broadstrike error, which is when the collar die (the punch that imprints the planchet with the design on the coin’s edge) fails to strike the coin at all, leaving it without any edging and a flattened-out center image.

Sometimes a die will strike a planchet wildly off center. In these situations the die is not the culprit; rather, there was a problem with the way in which the planchet was moved into position in the press. In extreme cases, an off-center coin will remain in the press to be struck a second time or more. In general, coins with multiple errant strikes are more prized by collectors than those with only one.

One of the most intriguing types of errors is a coin that has been struck properly but onto a clipped planchet, which is created when something is out of whack with the machine that stamped them out in the first place. For example, the machine stamps out a row of planchets too close to the one above it, the resulting bad blanks will look like someone took a bite out of them.

Planchet errors are also caused by stamping too close to the edge of the planchet’s source sheet metal, producing a blank whose otherwise perfect circular shapes are interrupted by straight edges on one side.

While production practices at U.S. Mints have improved in recent years, thus eliminating many of the most common historical errors, contemporary coins have not been immune to the occasional mistake.

For example, a crack in the die used to strike the reverse of the 2009 Formative Years Lincoln cent, which depicts the future president taking a break from chopping wood to catch up on his reading, can be seen at the bottom of the coin, through the second “U” in “Pluribus,” and up into the young man’s boot.

Because the crack resembles a bootstrap, this error, which may be widespread enough to be considered a variety, is known as the Bootstrap Lincoln Cent.

Even stranger are the die flaws that produced three different types of Wisconsin state quarters, all from the Denver mint, in 2004. The variations appear on the coin’s reverse and affect the number and orientation of the leaves on an ear of corn.

In the normal coin, the ear has a leaf on the left that arcs up and then down to the left. In a variation of that coin, there appears to be a second leaf below that one, rising out a wheel of cheese that sits below the ear of corn. A third 2004-D Wisconsin quarter shows that same extra leaf, only this time it is bent down and to the left. Inexplicable.

Finally there are so-called blundered dies, which refer to dies that were simply made incorrectly—unlike a doubled die, a blundered die suggests human rather than mechanical error. The most famous example of this sort of error is the 1982 dime, which was minted in Philadelphia but failed to identify itself with the “P” mint mark. An estimated 14,000 to 15,000 of these error dimes made it into circulation, which makes it a popular coin for many collectors.

About our sources | Got something to add?

▼ Expand to read the full article ▼

Best of the Web (“Hall of Fame”)

Legendary Coins and Currency

Legendary Coins and Currency

This online exhibition from the Smithsonian's National Museum of American History is a great way to get an overview… [read review or visit site]

Society of U.S. Pattern Collectors

Society of U.S. Pattern Collectors

Home to the Society of U.S. Pattern collectors, this well-organized site provides in-depth information on pattern c… [read review or visit site]

Clubs & Associations

Other Great Reference Sites

Most watched eBay auctions    

Pretty 1972 Double Die Obverse Pcgs Pr65bn Gem Colorful Toned Lincoln Cent1955/55 Ddo Lincoln Cent Penny, Highly Collectible Choice Bu Key Date Mint Error1955 1955/55 Ddo Doubled Die Obv * Pcgs Xf45 Ogh * Lincoln Wheat Cent 1c $2,000+1858 Seated Liberty Half Dime Off Center Misstrike Error Us Coin Great Detail1955 1955/55 Ddo Doubled Die Obverse * Pcgs Au58 * Lincoln Wheat Cent 1c $2,200+1937-d 3 Legs Buffalo Nickel Error Choice Au+ Three Legged Full Horn Rare!1918/7-d Pcgs Buffalo Nickel Pcgs G 04 ** Highly Desired Key Date Mint Error!1955 Flat Pack Proof Set With Envelope Mint Error No Blue Medallion Token!1942/1-d Mercury Dime, Avidly Pursued Key Date Mint Error, ** Free Shipping!1857-s $20 Ss Central America, 20b Bold S Gold Foil Label, Pcgs Ms65 Cac1995 Double Die Obverse Lincoln Cent Pcgs Ms 68 Rd1938-d/s 5¢ ~ Old Holder Pcgs Ms-661988 Ngc Ms-69 Obverse Struck Through Mint Error One Oz Silver American Eagle1989 2-pcs. Chain-strike Off-center Cents1883/2 Shield Nickel, Highly Desired Choice Au++/unc Rare Key Date Mint Error!Die Set-up 1883 Hawaii Dollar Medal1955 1955/55 Ddo Doubled Die Obverse * Pcgs Au53 * Lincoln Wheat Cent 1c $2,200+1937-d Buffalo Nickel, 3-legger, Pursued Choice Au++/unc Key Date Mint Error!1930 5¢ - Double Die Obv Fs-1011976-d 5c Mint Error Pcgs Ms64rb *mint Error* Struck On Cent Planchet1940-d/d 25¢ ~ Rpm #1 Old Holder Anacs Ms-651954-s/d 5¢ ~ Omm #1 Old Holder Anacs Ms-641968-s 25¢ ~ Double Die Reverse Die #1 Anacs Proof-661807/6 1c Large 7 Draped Bust Cent Error Xf+ Near About Uncirculated Rare!1953-d Lincoln Head Cent. Error. Off Center. 974662008 $1 J.q. Adams Missing Edge Lettering Pcgs Ms-67Mint Error 1888-o Morgan Dollar - Pcgs Slabbed Ms62 - Vam-1b Early Die StateMint Error 1888-o Morgan Dollar - Pcgs Slabbed Ms63 - Vam 1b Early Die State1953-d/s Wash. 25¢ ~ Old Holder Anacs Ms-641935-s 5¢ -s/s Rpm Old Holder Ngc Ms-651955-s Ngc Ms-66 Rd Reverse Retained Die Break Mint Error Lincoln Wheat Cent(2007) George Washington Dollar - Ngc Ms 66 - Mint Error: Missing Edge LetteringLot Of (20) Error U.s. Cents1966 Kennedy Double Die Obv - Doubled Profile Ngc Sms 66 * Rare! *Double Clipped Planchet & Off Center 1980 Lincoln Cent Penny Error Us Error Coin1972 1c Lincoln Cent Error Struck On 10c Dime Planchet Anacs Ms63 Very Rare!1999-p Del. 25¢ ~ Double Struck In Collar Pcgs Ms-621982-p 25¢ ~ Struck On 5¢ Plan Old Holder Anacs Ms-611964-d 25¢ ~ Struck On 5¢ Plan Pcgs Au-552008 $1 Monroe Missing Edge Lettering Pcgs Ms-67Rare Estate Found 1995 Ngc Double Die Error Ms-68 Red Penny 1 One Cent Us Coin1950-d/s 25¢ Over Mintmark~ Old Holder Anacs Au-501970-d 25¢’s – On Dime Stock Thickness1941-s/s 25¢ ~ Wrpm-004 Old Holder Anacs Ms-631952-s/s 25¢ ~ Rpm 001 Old Holder Anacs Ms-651963 25¢ ~ Double Die Obverse Old Holder Anacs Ms-646. A Partial Date Lincoln Cent Double Struck, 2nd Strike Is Off CenterLincoln Cent Cud Die Break Error1904-o Morgan Silver Dollar, Ngc Graded Mint Error Rotated Dies Unc Details1966 Kennedy Double Die Obv - Doubled Profile Ngc Sms 67 * Rare! *$1 1972-d Eisenhower Dollar Major Struck Through Grease Bu1970-s Proof Doubled Die Obverse Kennedy Half Dollar Ddo-0011931 S Lincoln Wheat Cent * Scarce Date * ?strike Thru Error? * You Grade It!25c 1983-p Washington Quarter 55% Off-center Bu1835 1c Error Coronet Or Matron Head Large Cent Coin Penny Vf+ Scarce Date!!1937-d Buffalo Nickel, 3-legger, Collectors Favorite Key Date Mint Error!2010 Sac $1 Missing Edge Lettering Pcgs Ms-66Copper/nick 1974 Ike Dollar Error Off-center Obverse Left 2mm Rim-no Right Rim1995 Lincoln Cent Double Die Obverse Ngc Ms68 Red Ddo3. New Machine Strike 2015 D Lincoln Cent With End Of Sheet Clip Error / Unusual