A rare Canada 1851 Queen Victoria 12d plate proof multiple is set to be among the stars of a stamp auction in Sydney, Australia on May 23.
The black imperforate block of four, produced on Indian paper mounted on card, has been stamped multiple times with "SPECIMEN" in carmine.
Multiples of the stamp are extremely rare, explaining the A$12,000 ($12,360) estimate put on the piece.
A superb collection of kangaroo stamps will also be on offer. The pick of the bunch is a rare third watermark £2 purple-black and rose offering.
According to the auction house it features a "break in upper shading line Great Australia Bight", and a "break in shading line above W of TWO and retouched shading lines left of WA coast".
Its rarity should ensure that it achieves around the A$8,000 (US$8,240) price mark.
The auction will also feature one of just three examples of a superb rarity from the Japanese occupation period in British Malaya.
The 1942 $500 purple and orange features a red oval Okugawa seal and a "DAI NIPPON/STAMP OFFICE PENANG" date stamp. It has an estimate of A$45,000 ($46,350).
PFC Auctions' online sale runs until May 24. It stars these four superb investment-grade postage stamps from Great Britain.
Rare British stamps are performing superbly at auction. The 30 leading collectible British stamps have soared in value by 10.8% pa since 1998, according to the GB30 Rarities Index.
Paul Fraser Collectibles will bring you all the key results from this sale later in the month.