The 90c Carmine & Black with an instantly recognisable image of Abraham Lincoln is a beautiful stamp. Although not an extreme rarity in itself, it is difficult to find an example in really good condition.

The example of the 1869 stamp in Robert A Siegel's 'Hampshire' auction yesterday was an extremely fine gem example. Graded at XF-Superb by the PSE (Professional Stamp Experts), it is one of only two pieces known to have achieved that grade.

90c Carmine & Black stamp depicting Abraham Lincoln

The PSE's decision is justified by the colours, original gum, fine centring and un-cramped margins.

Estimated at a very reasonable $13,000, the deep colours of the stamp caught the eye of more than one bidder and it was rapidly buffeted up to two, three and even four times that price, finally selling at an impressive $55,000.

Results like this provide a great example of how collectible stamps can be a strong investment. With conditional rarities this is particularly straightforward: maintain the condition whilst other examples fade and crease with less careful owners, and they become more valuable.