International stamp collectors are all aflutter this week as Hong Kong prepares to host an auction of rare Chinese stamps including a copy of the fabled "1897 Red Revenue'' - known as the most valuable Chinese stamp there is.

Hosted by Interasia Auctions, the sale will feature 2,200 lots representing the stamp and postal history of China, Hong Kong and Asia and will be held on July 31-August 1 at the Park Lane Hotel in Hong Kong.

International collectors will be able to bid online for such items as the 1897 Red Revenue Small 2c Green Surcharge which has become known as the "The Red Lady in the Green Dress'' and could sell for as much as HK$10 million (990,000 euros), according to estimates.

Another Red Revenue last February was sold for HK$5.52m (546,000 euros) at the Zurich Asia auction, thereby becoming the most valuable Chinese stamp ever auctioned.

There are only nine known examples of the Red Revenue in existence and two of them reside in the China National Postal Museum in Beijing.

One more interesting item on display will be the examples of the "Elephant'' stamps which were rejected when authorities were deciding on the nation's first stamps in 1877. A dragon design was eventually chosen when the first stamp was released in the country in 1878.

China's rising middle class has only just recently latched on to stamps as a sound investment and that has brought the nation's previously secretive collecting community out into the open - much to the delight of collectors all over the world.

Stamp collecting was banned in China during the Cultural Revolution (1949-1976) - as it was considered a frivolous pastime - and so collectors were either forced to hide their wares away, or ship them overseas for safety.

The title of the world's most expensive stamp goes to a Swedish misprint - the "Treskilling Yellow'' - which was printed in 1855. Originally costing three shillings, it was sold at auction in Geneva in May with sales organizers tight-lipped on whether the new owner topped its previous sales record of 1.59 million pounds (1.9 million euros). It was "still worth more than any other stamp,'' was all they would say.