In 1999, the U.S. Mint made a drastic mistake by producing the first Mint State $5 and $10 Gold Eagles bearing a "W" mint mark. In 1999, only Proof Gold Eagles were intended to bear the "W" mint mark. This mistake has left us with a lot of puzzling unanswered questions about the production and existence of the 1999-W $5 and $10 Mint State coins.
The year 1999 turned out to be a very busy year for the U.S. Mint. It received a tremendous and unexpected demand for American Gold Eagles. Many believe the Mint was in such a rush to produce 1999 Gold Eagles that in an attempt to meet the public's demand, it inadvertently mixed a proof die into service. Another possible theory is that the Mint may have intentionally put a proof die into service in order to meet the public's demand. Whatever the case may be, we can be certain the coins should not exist today.
The huge demand for 1999 Gold Eagles was more than likely created by collectors and investors who were worried about the upcoming Millennium year and some of the potential issues that could have been created by Y2K. Many decided to purchase American Gold Eagles as a safeguard to any potential problems arising due to the upcoming Millennium year. In return, many purchasers of 1999 Gold Eagles decided to purchase mainly fractional issues, since they are much cheaper and more affordable.
Going forward, sometime early in the year 2000, some of the first 1999-W Mint State Gold Eagles were discovered. The Mint did not provide any clues or give any indications as to how many of these coins were produced or why. It wasn't until years later that the Mint would give a very important clue as to how many coins could have actually been produced.
In 2005, a U.S. Mint spokesman issued a statement indicating that an estimated 6,000 Mint State Gold Eagles are produced from each pair of dies. If this was the case for the 1999-W Mint State Gold Eagles and only one pair of dies was used, a 6,000 production figure for each would not be unlikely. As of this writing, 11 years have passed and there has been no indication or supporting evidence that more than one pair of dies was used to produce this modern key issue. Therefore, if only one pair of dies was actually used and about 6,000 coins were made, this would make both coins very scarce in the Mint State Gold Eagle series. There is a good possibility that some of these coins are still out there unrecognized by collectors as being the elusive 1999-W Mint State Gold Eagles, because they can be confused with Proof coins since Proofs also bear the "W" mint mark.
Fred Weinberg, a U.S. coin dealer specializing in major error and U.S. coins, indicated he bought hundreds of the 1999-W Mint State Gold Eagle coins from a major mint distributor at one time. This distributor had already sent the majority of these dates and denominations to Japan for jewelry purposes. Julian Leidman, also a major dealer, buyer and seller of these coins, indicated he owned hundreds of these coins all at once and he mentioned he still buys and sells these coins because he believes they are a great modern issue. Finally, Hannes Tulving, another major U.S. Mint authorized dealer who has handled well over 1,500 of these coins over his career, believes that there are still many coins out there that are unrecognized, and many of them may still be hiding in rolls or even inside IRA accounts.
The most recent total population figures do not match or even come close to matching the 6,000 possible figures, even if one pair of dies was actually used. With many 1999-W gold eagles going overseas, tucked away in rolls, IRA accounts and even in private collections, we may never know the actual amount of coins in existence. So for now, we can only speculate.
In the future, there is a possibility the supply of these coins may increase if some of them ever show up from the above mentioned sources. However, many years have gone by and the supply has not significantly increased. So far, the demand has exceeded the availability.
Today, the coins can still be obtained at reasonable prices considering their very low possible mintages. However, don't be surprised if these coins appreciate in price as they have a very strong potential, especially since they are key coins in the very popular American Gold Eagle series!