1999-W $10 Gold Bullion Coins by Variety | $10 Gold Bullion Coins by Date | U.S. Gold Bullion Coins by Denomination

Obverse of 1999-W $10 Gold Bullion Coin - Unfinished Dies     Reverse of 1999-W $10 Gold Bullion Coin - Unfinished Dies

1999-W 10 DOLLARS
GOLD BULLION COINS - Unfinished Proof Dies

PCGS No: 99942

Mintage: Unknown (estimated 1,000)

In 1999, the Mint at West Point, New York accidentally produced what may become one of the most important rarities of the 20th Century by striking a limited quantity of Uncirculated 1/4 ounce American Eagle gold coins with the "W" mintmark below the date.  Normally, the mintmark appears only on Proof versions.  However, in this case, the dies never received the special polishing that gives Proof coins their deep, mirror-like qualities.  No one knows exactly how many were struck, but experts estimate that only 400-600 examples have been found since the mistake was first discovered in 2000.

How did the Unfinished Proof Die 1/4 ounce American Eagle gold coin come about?  The answer comes from examining how the Proof versions are created.  Proof coins are struck on special, high-quality presses using specially prepared blanks (planchets) and specially prepared dies.  The emphasis is on quality over quantity and the goal is a coin with bright, mirror-like fields surrounding frosty design elements, thus creating what is known as a "cameo" effect.  Special care is taken throughout the process to ensure that the final product (the coin) is as perfect as possible.  This special care automatically limits production -- in 1999, the Mint at West Point produced only 34,416 Proof 1/4 ounce American Eagle gold coins.  

On the other hand, the production of Uncirculated examples focuses more on quantity than quality (although the final coin is still impressive enough).  The number of coins produced is limited only by the availability of gold bullion, by estimated demand for the coins, and by other production priorities -- in 1999, the Mint at West Point produced 564,232 Uncirculated 1/4 ounce American Eagle gold coins.

Using the numbers just listed, we see that more than 16 Uncirculated coins were produced for every Proof example, highlighting the relationship between quality and quantity.

Great care is taken to segregate the Proof production area and all of the materials used in it.  The fact that a die originally marked for use in the production of Proof coins somehow made it into a press used to strike Uncirculated coins is simply amazing.  Proof dies are carefully accounted for...how did this one escape?  Press operators carefully scrutinize the dies before they are placed in the presses...how did the operator miss the mintmark on this one?  Random coins from production runs are examined for quality control...how did they miss the mintmark?  The very existence of the Unfinished Die 1/4 ounce American Eagle gold coins seems to have required several lapses in quality control.

How rare will Unfinished Proof Die 1/4 ounce American Eagle gold coins turn out to be?  A lot depends on how quickly the error was discovered at the Mint and how many actually escaped.  Did the press operator notice the mintmark and stop the run?  If the error was discovered, was an attempt made to recover and destroy the coins that had already been minted?  Even if we knew the answers to these questions, we may never know the exact number of Unfinished Proof Die coins that were struck.  But, we do know that after a year of intense searching for these rarities, surprisingly few have shown up.

What are they worth?  Recent sales have occurred in the $500-1,000 range.  If the rarity holds, these coins have every chance of being as valuable as the much more common 1995-W Proof $1 Silver Eagle (currently priced at $3,200 in Proof-69).

PCGS has graded less than 200 of the "Unfinished Die" coins, with half of them appearing in the MS-69 grade.  

Images courtesy of Global Certification Services, Inc.

Sources and/or recommended reading:
"The PCGS Population Report, January 2002" by The Professional Coin Grading Service