The enormously popular U.S. 50 State quarter series began in 1999. For the first time, a U.S. proof set contained nine coins: the cent, nickel, dime, half dollar and all five of the first commemorative statehood quarters issued that year: Delaware, Pennsylvania, New Jersey, Georgia and Connecticut. The double-struck engravings have a beautiful frosted finish and dazzling mirror backgrounds. Transparent plastic cases protect the coins while displaying both sides.
It was originally issued by the U.S. Mint for $19.95. As the quarter series grew in popularity, new collectors became interested in original first year proof issues and prices for the 1999 proof set rose considerably. For a few years the set sold for over $100 on the secondary market.