Mike F. writes: I have a 1999 Connecticut State quarter that is a doubled die coin. The doubling can clearly be seen on the tails side of the coin. The letters that spell Connecticut and the 1788 are clearly doubled by looking at the coin with the naked eye.The doubling can be seen just about every where on this side of the coin with a 5x magnifying glass. Could this really be worth up to $1000?
A “doubled die” error is not an error of striking a coin but an error in manufacturing a die. It is the die that would have the doubling. All coins struck with that die would be identical and show the same defect. There would be thousands or even tens of thousands of a doubled die error. A good example is the 1955 doubled die. At one time, rolls of this error coin were available.
The doubled die effect is caused by multiple hits by the master hub to create a deep impression (in a negative image) in the potential working die. The error comes when the hub rotates slightly so that the subsequent hit to the working die is out of alignment with the previous one. There are many instances of minor doubling on some dies, only the spectacular ones become desirable.
The latest techniques are suppose to eliminate the possibility of doubled dies but then again anything is possible. For your coin to be a doubled die there would have to be many more coins exactly like it.
A more likely explanation is “shelf-doubling” (called so because of the characteristic shelf effect caused on this error). These are unique and are caused by a loose collar that holds the blank in place when it is struck. The collar is a device that holds the planchet (blank) in place while the dies strike the planchet. The collar also contains the reeding that is imparted when the coin is struck. The “chatter” causes a doubled impression but one is in lower relief than the other (the characteristic “shelf”). A workman who discovers the loose collar, simply stops the press and uses a screwdriver to tighten the collar.
Shelf doubled coins are generally unique and unless the doubling is severe and spectacular, they do not bring a premium in the coin market. That is not to say they are not interesting and worthy of study, just that they have no additional beyond their face value. Only true and extreme doubled dies bring a significant price.