Educational Series – What is a Re-punched mint mark (RPM) ?

A re-punched mint mark, or RPM, is a coin that shows two or more mint marks on the same coin. This was caused by human error in the punching of the mint mark onto the coin die . Before 1990, a U.S. Mint engraver manually punched the mint mark into each individual working die.

Occasionally, due to human error, a die would get two or more punches of the same mint mark, sometimes in almost the same location, and sometimes at 90 or 180 degree rotations. Some times the Mint engraver would catch these defective working dies before any coins were produced from them.

1959-D Lincoln Cent re-punched mint mark.
1959-D Lincoln Cent re-punched mint mark.

A working die that had multiple punching of a mint mark would strike coins with multiple impressions of the same mint mark letter. Such specimens are called re-punched mint marks, or RPM’s. In the Coin Collecting Hobby these Re-punched Mint Marks (RPM) are very collectible.

1954-D over D re-punched mint mark on a Lincoln Cent
1954-D over D re-punched mint mark on a Lincoln Cent
1879-O with a regular "O" over a horizontal "O" re-punched mint mark.
1879-O with a regular “O” over a horizontal “O” re-punched mint mark.

When the Mint started using mint marks (letters) in the early 1800’s to identify the various branch mints at which coins were being struck, the mint mark was hand punched into the working dies that would be striking the coins. It was the last portion of the design to be placed on the die. These mint mark letters are as follows: D for Denver, S for San Francisco, CC for Carson City, O for New Orleans, P for Philadelphia, and W for West Point.

A Mint engraver would take a thin steel rod (punch) that had the mint mark engraved on one end and hold it in place on the working die where the mint mark was to be applied. Using a mallet he tapped an impression of the mint mark into the die.

In most cases it was necessary to strike the punch more than once with the mallet in order to leave a satisfactory impression of the mint mark in the die. When the multiple mint mark impressions are from the same mint mark (a D punched over a D, or an S punched over an S), the variety is known as a Repunched Mint Mark (RPM) variety.

Re-punched mint mark terminology

The reference of D/D is used to refer to a “D punched over a D.” Likewise, S/S is used to refer to an “S punched over an S.” So in today’s modern coinage, the most affected mint marks with RPM’s would be the D (Denver) and S (San Francisco) mint marks as they are the mint marks most familar to the collectors.

When people describe mint mark punches, a direction may be implied the D/D or S/S mint marks, such as D/D North or D/D West. When a direction of an RPM is given, that direction refers to the direction of the weaker mint mark punches. The weaker mint mark punches were the first to be punched into the working die and did not penetrate as deeply in the working die. Eventually a stronger primary punch would be the deepest impression in the working die, completing the addition of the mint mark symbol and creation of the RPM on that working die.

1954-S Lincoln Cent re-punched mint mark
1954-S Lincoln Cent re-punched mint mark. This re-punched mint mark may have used a broken punch, or each “S” was of a different size.
1954-S Lincoln Cent re-punched mint mark
1954-S Lincoln Cent re-punched mint mark. Notice the notching at the top and bottom of the re-punched “S”.

Educational Series – What is a Doubled Die?

A Doubled Die is a term in coin collecting used to refer to doubling in the design elements of a coin. Doubled dies can appear as an outline of the design or in extreme cases, having design elements and dates appear twice in an overlapping fashion. Doubled dies can be seen on the Obverse or Reverse of the coin – or both ! They are commonly referred to as Doubled Die Obverse (DDO) or Doubled Die Reverse (DDR).

What are Doubled Dies worth ?

Doubled die error coins can fetch significant prices when they are noticeable to the naked eye or occur in a popular coin series. A few examples are the 1955 doubled die Lincoln Wheat cent, the 1969-S doubled die Lincoln Memorial cent, the 1972 doubled die Lincoln Memorial cent, the 1964 doubled die Kennedy half dollar, the 1961 doubled die Franklin half dollar to name just a few.

1972 Lincoln Cent Doubled Die Obverse Die 001
1972 Lincoln Cent Doubled Die Obverse Die 001

In the coin collecting world, proper terminology for this occurrence includes the letter ‘d’ at the end of the first word, hence “doubled die”. The term “double die” without the first word ending in ‘d’ is not proper numismatic terminology.

How are Doubled Dies created?

Doubled dies are created when the master die imprints an additional, misaligned image onto a working die. Its the working die that has two or more pressings, not the planchet. A working die with several misaligned pressings is taken to a press where coins are made with that working die.

The different classes of Doubled Dies

There are many ways this misalignment of devices can occur, which have been grouped into eight classes:

Class 1 Doubled Die, Rotated – Results when the working die receives an additional pressing from the master die that is misaligned in a clockwise or counterclockwise direction.

Class 2 Doubled Die, Distorted – Results when the master die design moves toward the rim between hubbings.

Class 3 Doubled Die, Design – When a master die bearing a different design stamps a die bearing another design.

Class 4 Doubled Die, Offset – The working die receives an additional pressing that is misaligned in an offset direction.

Class 5 Doubled Die, Pivoted – The working die receives an additional pressing that was misaligned via rotation with a pivot point near the rim.

Class 6 Doubled Die, Distended – The working die receives an additional pressing from a master die that was distended.

Class 7 Doubled Die, Modified – The master die is modified between the working die’s pressings (e.g., a design element was chiseled off).

Class 8 Doubled Die, Tilted – A working die and/or master die is tilted during a hubbing.

Doubled dies are a result of the way in which in the United States Mint dies are created. Before 1997, die pairs (hammer die and anvil die) were made by hubs that contained the raised design elements that were intended to appear on the coin. The blank dies were heated (to soften them) and then were pressed against the hubs to transfer the design from the hub to the working dies.

Creation of a working die, with the master die on top of the press.
Creation of a working die, with the master die on top of the press. Mint workers would remove the die, check for a complete transfer. If it was not complete, another pressing would occur. Should the second pressing be misaligned, a “doubled die” was created.

Often, one impression was not enough in every case to transfer the design elements from the hub to the die, so multiple impressions were required to transfer enough of the design. For this reason, after the first impression was made, the die was reheated and prepared for a second impression.

Creation of a working die
Creation of a working die. If the design did not transfer completely, it was heated and pressed again.

The mint workers would try to use guides to align the hub and the working die perfectly to prevent overlapping, or a doubled die. If the die was acceptable within the mint standards, the working die would be put in a press and coins would be minted. If the engraver thought something was amiss, they would stop the press and investigate. A lot of variety coins have escaped the mint prior to 1996.

A senior mint worker examining the coins being stuck by the mint presses.
A senior mint worker examining the coins being stuck by the mint presses.


It is when mint workers failed to align dies properly during this process that doubled dies were produced. In many instances three to four impressions were required, which could but rarely led to tripled and quadrupled dies.

Kennedy Hald Dollar Doubled Die Obverse
Kennedy Half Dollar Doubled Die Obverse. This doubled die has that classic “cookie cutter” look.

In summary, prior to 1996, after each impression, a heated working die is removed and checked to see if the entire design and its details were successfully transferred from the master die, to the target working die. A doubled/tripled/quadrupled die is created if these multiple impressions pressed onto the working die were not properly aligned. If the die was acceptable and within the mint standards, the working die would be put in a press and coins would be minted. If the engraver thought something was amiss, they would stop the press and investigate. A lot of variety coins have escaped the mint prior to 1995.

Note: you will see HUB used in place of master die in may locations – it’s the same thing.

New way to make working dies but doubled dies are still being created

Modern coining methods have greatly reduced the number of these varieties due to the use of a single squeeze hubbing method during die creation, but doubled dies in modern United States coinage are still occurring.

With this new die making process implemented after 1996, dies only require one impression of the hub to transfer all of the design from the master die to the working die. But it has been discovered that the pressure created is so great, that some working dies tend to slightly rotate during this process.

Educational Series – What is a die variety coin ?

What is a Die Variety Coin? What is a Die Variety ?

A die variety is a variation to the normal design to a coin die, usually caused by human error or defects in the preparation or maintenance of the coin dies. Varieties are typically produced on working dies, instead of on the master die.

Typical die varieties include doubled dies (Doubled Die Obverse and/or Doubled Die Reverse; DDO or DDR), re-punched mint marks (RPM’s), Over mint marks (OMM) and re-punched dates (RPD’s), over dates, plus a small number of other minor varieties introduced during the strike of the coin.

1955 Lincoln Cent with doubled died obverse
1955 Lincoln Cent with doubled die obverse
1960-D Lincoln Cent small date over large date
1960-D Lincoln Cent small date over large date
1942 over 1941 Mercury Dime
1942 over 1941 Mercury Dime over date
1961-D Lincoln Cent re-punched mint mark
1961-D Lincoln Cent re-punched mint mark

Educational Series – Die Cracks and Die Breaks

What is the difference between a Die Crack and a Die break on a coin ?

Die cracks are small hairline cracks that appear on a die which is used to make coins. Die craks occur due to undue stress or wear put upon the working die. Die breaks may start as a die crack and over time, The crack simply starts to shatter a working die. Die breaks tend to show up much wider on a die and die cracks have the potential for the die to disintegrate in a very short period of time.

At the CONECA table at shows, I get a lot of questions about die break and die cracks. I basically try to break these two categories out. I am old school, and I have learned from some of the best.

How die cracks and die breaks happen

The first thing that normally happens to a coin when things go wrong, is the die begins to crack. At first, the die cracks are hair thin. I typically see the die cracks in the head area of the Lincoln Cent. Some of these die cracks may go from the head area towards the rim. Most of the die cracks run towards the WE in In God We Trust. I have seen die cracks start on Lincoln’s jacket area and travel slowly toward the southern rim. Again, these die cracks are pretty thin.

When looking at die cracks on a Morgan Dollar happen, they are seem to happen in a circular format, especially close to the rim. These die cracks can travel through many of the letters on the reverse of the Morgan Dollar. The die cracks seem to be relatively thin in width due to the size of the coin.

Now, the die breaks. Die breaks seem to become quite uneven in width. Die breaks are blotchy, and can be very wide. I have found a good example of a Lincoln cent with both the die cracks and die breaks. Die breaks typically make people wonder how this piece of the die does not fall out of the die. In the case of the Lincoln Cent below, it looks like the rim of the die was still intact, but that piece of die between the crack would not last much longer.

Die cracks and die breaks end up happening over time. Some of the design features of the die, and some times the metal composition play into the reason die cracks and die breaks happen. Most of the time, its simply due to stress, wear and tear on the working die. I have seen a lot more Die cracks in cents, followed by die cracks and die breaks in Morgan Dollars, then quarters then half dollars.

What is the Value of a die break or die crack?

The value of die cracks and die breaks is very minimal. Most of the collectors state that die breaks and die cracks are simply damage, and these are not a true error or a variety.

There comes a point when die cracks and die breaks become dramatic, and then may become a collectible item due to the sheer spectacle it becomes. The Lincoln Cent below may be an example of where it may fetch a premium since it shows both the die cracks and die breaks.

How much does a die break or die crack cost ?

The good ole’ saying says, to a collector, a coins’ value is only as high as a collector is willing to pay for it. Typically, if a coin has some pretty dramatic die cracks, it may fetch between $1,00 to 5.00 on a good day. A coin with dramatic die breaks  – I mean a wow spectacle where its a sheer wonder why the die hasn’t disintegrated may fetch several hundred dollars or more.

Some of the major die breaks may even make it into some of the magazines or books. It all boils down to what people wish to collect, and how much they are willing to spend.

With every roll or bag that is out there, it’s like a lottery. One never knows what exactly will be pulled out of the roll or bag and in some cases some great damaged coins, errors and variety coins can be pulled.

A Lincoln Cent with Die Cracks and Die Breaks

Can YOU see which of the abnormal lines on this Lincoln Cent are Die Cracks and which ones are Die Breaks? You may have to use your CTRL key and mouse wheel to make the photo a little larger. When you are done, press CTRL+0 to get the screen back to normal.

Lincoln Cent with Die Cracks and Die Breaks
Lincoln Cent with Die Cracks and Die Breaks

Stand by for another post on a group of strike through’s I found digging through a bag of Lincoln Cents. In the mean time, here is a photo of the Lincoln Cent with the die cracks and die breaks.