Investors and hobbyists pursue the American Eagle series of bullion coins for different reasons.

Hard-money types are looking for an economic hedge when they obtain gold, silver and platinum pieces in various sizes.

While the collector may enjoy building a portfolio of hard assets, other motivations are also involved. The numismatically inclined often seek to build a complete set of American Eagles.

For a number of dedicated hobbyists, the ultimate in quality – as in Mint State 70 or Proof 70 – is the goal. While few American Eagles leave the U.S. Mint in less than MS-68 or Proof 68, a "perfect" 70 can be elusive.

To cite one example, a 2004-W American Eagle tenth-ounce $10 platinum coin certified as Proof 70 by a major grading service has sold for more than $2,000 on at least two occasions in 2007. That's an attention-getting price for a 3-year-old coin with a melt value of less than $150.

American Eagle silver coins – supposedly the province of lower-budget shoppers – can also fetch eye-popping sums in the magic 70 grades.

How about the certified MS-70 1989 American Eagle dollar that went for $700, or the 1993 silver bullion coin in the same grade that was purchased for more than $1,800? Proof 70 deep cameo or ultra cameo 2000 American Eagle silver coins have sold for $500 or more in auctions.

If a certain American Eagle coin is scarce (relatively speaking) in 70, does it mean such a gem will always be hard to find? Current perceptions could change in the future.

Uncirculated and Proof Eagles are the only precious metals option for Americans who desire hard assets in an Individual Retirement Account. All IRA-designated American Eagles must be held in an approved depository outside of the physical possession of the account holder.

The coins are typically purchased by brokerage firms who specialize in this kind of transaction. The buyer never handles his American Eagles, which can be sold into the market at some future date. With the baby boom generation moving into the retirement years, a growing number of IRA redemptions can be expected in coming years.

While no one knows exactly what is sitting in storage, it's safe to say that at least some high-quality American Eagles await discovery. It will be interesting to see how today's retirement account holdings affect future population reports.