What may be America's oldest silver dollar has become the world's most expensive coin, with its owner saying it changed hands in a private transaction between coin collectors for nearly $8 million.

Five of the finest known surviving examples of 17th century colonial Massachusetts silver coins, with a combined value of approximately $1 million, will be displayed at the Santa Clara Coin, Stamp & Collectibles Expo.

Steve Contursi, holds up his rare, 1803 Draped Bust silver dollar, insured for $1 million, at the Santa Clara Coin, Stamp & Collectibles Expo, Thursday, Nov. 17, 2005, in Santa Clara, Calif.

For America's first silver dollar, the buck stops here: Colorado Springs, Colorado; Kansas City, Missouri; and San Francisco, California.

Any 1794 Flowing Hair silver dollar – even a well-worn example – is a special coin. One piece stands far above the rest in this elite company.

Currency experts say they have identified a 210-year-old silver dollar that could be the first one coined by the United States Mint.

In March, Steve Contursi paid millions for one 1794 silver dollar and more for the collection it was in. But he thought the expensive and surprisingly shiny coin, 40 millimeters in diameter, might be something even better, something no one realized still existed.