An enlarged replica of a block of four rare United States airmail error stamps (AFP)

NEW YORK: It was a blockbuster trade not in sports but in multimillion dollar stamps.

A block of four stamps from 1918 bearing the image of an upside-down plane valued at US$3 million were swapped on Wednesday for a single stamp with an equal value the world's highest-priced single stamp.

A California collector traded his four "Inverted Jenny" stamps for an 1868 one-cent "Z Grill" stamp to fill out what experts believe is the only complete collection of 19th-century US stamps.

"This isn't like kids swapping stamps," said Charles Shreve, president of Shreves Philatelic Galleries in Manhattan, where the trade was made. "The 'Z Grill' is like the Holy Grail of US stamps it's the Hope diamond of American philately."

At the centre of Wednesday's swap are five stamps that sold for 97 cents in 1918 at a Washington, DC post office. At the heart of the deal is Bill Gross, of Newport Beach, California, known as "the bond king" for his investment success at the Pimco fund giant. Gross was missing the 1-cent "Z Grill" stamp owned by Donald Sundman, president of Mystic Stamp Company of Camden, New York.

Two weeks ago, Gross paid almost US$3 million at a New York auction a world record price for any stamp for the four 24-cent stamps with the mistakenly printed upside-down Curtiss JN-4 biplane, known as "Jenny," that first delivered the country's air mail.

Gross now has "a comprehensive, complete collection representing every 19th-century US postage stamp," said Shreve, whose company had placed his successful auction bid for the four stamps.

Small, blue-hued and bearing the image of Benjamin Franklin, the "Z Grill" is so named because of the waffle-like grill pressed into the back that better absorbed postmarks and prevented people from washing off the cancellation and reusing the stamp.

It's one of only two existing "Z Grill" stamps; the other one is owned by The New York Public Library.

"It's special. It's rare." said Sundman, who plans to show his "Inverted Jenny" block at exhibitions around the United States.

"Collectors find errors very exciting," he said. "It's the thrill of the chase and that you might find one."

Gross plans to exhibit his newly acquired "Z Grill" at the Smithsonian Institution in Washington in May, at the same time as the "Inverted Jenny" is to be displayed at the National Postal Museum, according to Shreve.

First, the stamp dealer must deliver the US$3 million stamp to Gross in California. It will be personally carried by Shreve, who would not reveal when or how, for security reasons.

(China Daily 11/04/2005 page6)