NEW YORK: There are only 100 “Inverted Jenny” stamps in existence. So when one goes on sale, it’s a big deal. The stamps are known for the printing error that created them. On the stamps is an image of the first plane used for airmail; The Curtiss Jenny. It’s an image that’s on thousands of stamps printed at the time. But on the Inverted Jennys, the image was accidentally – you guessed it – printed upside down. “The Inverted Jenny is the world’s most famous stamp,” owner of Siegel Auction Galleries Scott Trepel said. “It has its own legend.” Trepel – who has been a stamp collector since he was nine years old – will auction off one of the Jennys from a private collector on May 31 at the World Stamp Show in New York. The Inverted Jenny for sale is number 58 of 100 stamps. It’s the finest copy of the stamp known to be in existence, with a grade of 95 out of 100 by Professional Stamp Experts (PSE), the leading grading service of stamps. This stamp was last sold in 2005 for $600,000 and is expected to get much more this time around. “It has a catalog value of $1.6 million,” Trepel said. “I think everyone would be very happy if it went for that much.”