This weekend, a very special auction will take place at David Feldman Auction Galleries
Regardless of the fantastic sales of rare stamps being held by Spink Shreve in New York selling parts of Bill Gross's collection of European stamps, or the New Zealand stamps of Joseph Hackmey, the philatelic world's eyes will be most keenly focussed on Geneva.
That is because the most expensive stamp in the world, the unique colour error known as the Treskilling Yellow is going under the hammer - the only known example of its kind in the world.
The three skilling stamp would normally have been a turquoise colour, and it is thought that the yellow colour for the eight skilling stamp was used by accident with the 'cliché' for the three skilling piece.
The ordinary 1855 'Treskilling Green' is quite rare and collectible in its own right. But the yellow version, discovered unwittingly by a schoolboy and sold for no more that its turquoise brothers, went on to become the most rare and valuable stamp in the world.
Sold by the school-boy to a German expatriot dealer, then via an Austrian dealer to an aristocrat living in France, it returned to Sweden ownership between the two world wars.
After WWII, it was purchased by the King Carol II of Romania, then sold on to a Belgian magnate. Since then, it has been offered by David Feldman SA on three occasions (1984, 1990 and 1996) bringing the top result of CHF2,875,000 in 1996 (about $2.3m).
It was last sold privately by Thomas Høiland of Denmark to an anonymous buyer.
The subject of detective stories, cartoons, T-shirts and much more, the most valuable stamp in all philately is available in Geneva on Saturday, May 22 at 5pm with an estimate of €1.5m-2m.