A rare five-dollar gold piece and a prized silver dollar each could fetch $10 million or more in upcoming auctions, making the American rare coin market as attractive, though not nearly as glamorous, as fine art.

An 1822 Half Eagle five-dollar gold piece, one of only three known to exist, and an 1804 Silver Dollar dubbed the "King of American Coins" are expected to be among the top lots when the collection is sold in a series of auctions in New York beginning in May and continuing into 2017.