In the 18th century, American colonists used one ounce silver coins made by the Spanish. These "pieces of eight" were worth eight reales and could be fractioned into halves or quarters, as we do today with the modern dollar.
Pieces of eight were the most common coins used for commerce during the 16th and 17th centuries, as well as in 18th century America. Coins were made by countries like Spain, which was rich in the precious metals used to make coins. Although Great Britain was a major trading power, it had few natural resources to make its own coins. Likewise, there were no gold or silver mines in colonial America.
The value of a pieces of eight coin was based on the weight of the silver. At the time the coins were made, one ounce of silver was worth one dollar. The coin could actually be cut into eight pieces, or bits. Each bit was thus worth 1/8 of a dollar.
In today's market, a pieces of eight coin is worth much more than a dollar. For one thing, the price of silver has increased considerably since the days when pieces of eight were used as currency. Coins were made by hand individually, so there was some variation in design. Collectors and museums prize coins with clearly defined images, and these coins can be worth thousands of dollars.