One of the most unique errors to come from the United States Mint features an effect that is sometimes too minor to see with the naked eye. However, this type of error has been seen across a number of coins with different denominations over the years and are in their own way, a collecting niche to those who seek them.
While this next entry in the 100 Greatest United States Modern Coins series detailing the publication from Whitman Publishing is higher in ranking, authors Scott Schechter and Jeff Garrett make it a point to say that the coin is almost too rare to put on the list. Discovered by a dealer out of New Hampshire, this coin from the fourth edition of the publication is so rare that mintage cannot even be assumed.
#61 - 1990-S Doubled Die Obverse, Washington Quarter, Proof
First discovered in 1990 by a dealer from New Hampshire, the 1990-S Doubled Die Obverse, Washington Quarter Proof is so rare that less than fifty have ever been identified in a certified manner (both PCGS and NGC). To put that into perspective, the coins would have been disclosed in either the 1990 Proof Set or the 1990 Prestige Proof Set. Combined, over 3.2 million of those sets were issued total. Authors Schechter and Garrett estimate that there are 2,000-2,500 out there.
As far as the error is concerned, doubled dies are created when a die obtains two impressions of the coin’s design while being created. Doubling then happens when the hub or the die has slightly rotated. Some are minor while others are farther away from the point of rotation. On this 1990-S Washington quarter specifically, the doubled die effect can be found in two areas on the obverse. The date is the first and the ‘S’ mintmark is the second. The mintmark doubling is especially unique as it was not seen on a doubled die coin before this one. Up until 1985, the United States Mint added mintmarks to the Proof dies after they were hubbed. Anything after that was a part of the same process as the rest of the coin. The amount of separation is also to be noted with the coins. It is visible with the naked eye while most varieties have to be identified under magnification.
Since the first edition (#51), the coin has moved down ten spots.