A collector’s dream the discovery of a rare error on a U.S. stamp might result in a half-million dollars reward at auction June 16 in New York.

The error was found on a stamp sheet of 40 29-cent stamps printed in 1992 to commemorate the 200th anniversary of the New York Stock Exchange. The stamps depicted a view of the Stock Exchange building and a scene at one of its sessions. Atop the stamp are the dates 1792-1992.

A collector in West Texas bought a sheet, at the post office that contained 28 stamps with inverted centers and 12 with completely missing centers two errors on one sheet.

The anonymous owner put away the sheet for safekeeping but did not notice the errors until a careful examination on Dec. 2, 2001. Realizing the potential of his discovery, the owner contacted Greg Manning Auctions in New York, one of the top firms for auctioning stamps, coins, sports cards and other collectibles.

Manning says the sale could result in a $500,000 bonanza. The stamps will be auctioned in singles, pairs and blocks.

The authenticity of this error sheet has been verified by the U.S. Postal service and other professional stamp experts.

Manning says “This discovery is, without a doubt, the most important stamp-collecting event of the 21st century and is a wonderful opportunity for the thousands of new philatelists around the world to share its experience. A portion of the auction’s proceeds will go to charity with a directed share to a fund for the families of the victims of the Sept. 11 attacks.”