A stamp thought to be rare and valuable that was used to mail an absentee ballot now appears to be a fake, an expert said Tuesday.

The stamp thought to be the famous Inverted Jenny stamp was discovered as Broward County officials reviewed absentee ballots for the Nov. 7 elections. An official noticed the stamp was from 1936 and had an upside-down World War I-era airplane — the hallmark of an Inverted Jenny.

The envelope was taken out of a safe deposit box Monday and shown to reporters and photographers, said Mary Cooney, Broward County elections office spokeswoman. The images were sent to stamp experts.

Peter Mastrangelo, director of the American Philatelic Society, said after reviewing a digital photo that the stamp appeared to be counterfeit.

A true Inverted Jenny could have been worth as much as $300,000, Mastrangelo said.

There was no name on the envelope, so the vote didn't count. Under Florida law, elections officials will retain the ballot with the stamp for 22 months, according to the Florida secretary of state's office. After that, any action is up to the county elections supervisor.

The 24-cent Jenny stamps were printed in 1918. Sheets were run through presses twice to process all the colors, and on one pass, four Jenny sheets went through backward. Inspectors caught the errors on three sheets and destroyed them, but somehow, a sheet of 100 stamps got through.