The Three Dollar gold piece was a short lived U.S. gold coin issued from 1854 to 1889. The reason for it's creation was to make postage purchases easier. At the time of issue, a full sheet of postage stamps was $3.00. The three Dollar gold piece is considered a scarce coin in today's market. Two of the mint marks found on the three Dollar are D and O. The D mint mark was for the Dahlonega, Ga mint and the O was for the New Orleans mint. Both of these mints were taken over by the Confederates during the U.S. Civil War. The three Dollar coin is 90% gold and 10% silver.