Collectors will pay up to $600,000 for rare stamps at a coming auction despite the economic crisis, Sotheby's predicts.
The auction house said the stamp market, unlike jewellery and antiques, had not been affected by the regional downturn.
'It's not something like jewellery which you can buy any day of the week - rare stamps might only appear once every five years,' said Richard Ashton, director of Sotheby's postage stamp department.
A series commemorating Empress Dowager Cixi's 60th birthday, Chinese stamps used in Tibet and a postcard with a rare Hainan Island postmark from the 1920s are among $15 million worth of Hong Kong and China-related stamps to be auctioned on Thursday.
Another series featuring the Qing dynasty empress has an irregularity making the sheets of stamps even more valuable.
A bat in the design was missing from one stamp in one pane, said the postage stamp department's deputy director, Tony Banwell.