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    

1922 No D 1c No D Strong Reverse Die Pair #2 Lincoln Cent Error Very Fine Rare!1942/1 Mercury Dime, Highly Desired Mint Error, Choice Au++/unc Key Date!Wow 1969-s Double Die Obverse Lincoln Memorial Penny Cent | Pcgs Au 58 | 55031955 Double Die Obv Lincoln Cent Ngc Xf40 Bn Coin 6 Coin Error Lot1853/4 Seated Liberty Quarter Arrows & Rays Error Overdate Au+ Nearly Unc Rare!1909-s/s Lincoln Cent Wheat Penny, Near Gem Bu++/gem Bu Key Date ** Free S/h1876 Shield Nickel, Double-struck Date, Sharp Solid Gem Bu++ ** Free Shipping!1942/1 Mercury Dime, Key Date Mint Error, Details ** Free Shipping!198?-d Lincoln Memorial Cent - Bowtie Clip Error1999-w $5 1/10 Oz Gold Eagle #1 - Unfinished Proof Die Error - Rare - Pcgs Ms 681950-s/d 25¢ Rare Fs-601 Pcgs Ms-632008 $1 J.q. Adams Missing Edge Lettering Pcgs Ms-671970-d Lincoln Cent Struck Off Center Mint Strike Error Coin - Free Shipping$5 Gold ...1995 Olympic Coin Die Cancelled U.s. Mint.. Centennial Games, Atlanta1873 Indian Head Closed 3 Doubled Liberty Snow-1 Ddo Error Fine S-1 Ultra Rare!Us Coins! Huge Lot! Lots Of Silver, Wheat, And Error Coins!! Dont Miss Out!192- D Error Mercury Dime ""struck Off Center"" Extremely Rare1959-d Off Center Lincoln Penny Us Mint Error Coin Uncirculated1811/9 Capped Bust Dime, Seldom Seen Over-date Error, Choice Xf++/au Key Date!1959 25¢ Stk On Venezuela Centimos Pcgs 1972 Ike $1 Triple Clipped Plan- Pcgs Ms-631998 1¢ - Huge Broadstrike1999-d New Jersey 25¢ Triple Clipped Planchet1976-d Bi-cent. 50¢ Triple Clipped Planchet1976 Bi-cent. 25¢ - Double Struck26 Pc. Lot Of Mixed Denom Error Coins1839/6 Large Cent, Coronet Head, Ultra Rare Choice Fine Key Date Mint Error!1925 Pcgs Au53 U.s. Silver Peace Dollar Mint Error 1/3" Cracked Planchet Anan4032007 John Adams Presidential $1 Ngc Bu Missing Edge Lettering Error1982 1¢ Double Struck1999-w $5 1/10 Oz Gold Eagle #2 - Unfinished Proof Die Error - Rare - Pcgs Ms 682000-p Ngc Certified Mint Error Pf69 Uc American Silver Eagle $1 Coin An4039m1986 25¢ - Double Struck & Rotated Pcgs 1922 P$1 ~ ¼” Cracked Plan Pcgs Ms-62 Five Blank Type 2 Planchet Set - Penny, Nickel, Dime, Quarter And Half $ Lincoln Wheat Cent Die Cap Brockage Mint ErrorPcgs Ms64 "sample" 1956-d Silver Roosevelt Dime - Slab ErrorError Coin: Extremely Large Broken Die Cud On 1980-p Lincoln Cent1921 Morgan Dollar Anacs Ms63 Mint Error Struck Through Grease Hot 50 Vam-3f32007 George Washington Presidential $1 Ngc Ms65 Missing Edge Lettering ErrorUs 1898 Indian Head Cent Error Brockage Mirror Image1934 D Heavy Motto Washington Quarter Pcgs Ms63 Regular Strike Variety Dime Split Die / Struck Through Clad Layer Mint Error198x Lincoln Cent,*counter Brockage Strike*rare* Copper *us Mint Error Coin* 1986 1¢ Double Struck1860 Pointed Bust Fs-401 Indian Head Cent Ngc Au Details 1c Indian Penny Coin2003-p Missouri State Quarter Waffle Cancelled Error Ngc1999-w $5 1/10 Oz Gold Eagle #3 - Unfinished Proof Die Error - Rare - Pcgs Ms 681857 Flying Eagle Cent Graded / Slabbed Ngc Unc Details Obverse Lamination Error1942/41 Mercury Dime, Highly Desired Choice Bu++ Key Date Mint Error, Free S/h!1995-d Washington Quarter - 50% Off-center Strike2007 George Washington Dollar - Pcgs Ms 65 - Mint Error - Missing Edge Lettering1885-o Morgan Dollar Wildcard Vam! Xf True Double Die Date No Reserve! Mint Error 2007 George Washington Dollar - Ngc Ms65 - Missing Edge Lettering 2000 - Struck Thru Wire 15% Off Center Broadstruck Lincoln Cent Mint Error #11691978 25¢ - Struck On 5¢ Plan. Pcgs Au-582010 Sac $1 Missing Edge Lettering Pcgs Ms-651979 25¢ - Struck On 5¢ Plan. Pcgs Au-551861/0 Seated Liberty Half Dime, Richly Toned Choice Au++ Error * Free Shipping!