Secondary market popularity of an America the Beautiful 5-oz. silver bullion coin is difficult to predict; mintage is only one factor in higher premiums.

Some lots offered in online auctions virtually guarantee a bidder will lose money by placing almost any bid.

Sometimes the online auction experience can cause consternation.

Half dollars: A mysterious rarity

The eighth known, second finest 1817/4 half dollar, an ultra-rarity, was found in a load of fill dirt; now 11 are known. It last sold at auction for $164,500.

A preview of some forthcoming issues recently heard about, by no means comprehensive.