Every philatelist has heard of the Tre Skilling Yellow, the 1857 colour error which put Sweden on the map for stamp collectors.
The stamp, discovered by a schoolboy, was a yellow version of the usual turquoise-green stamp, thought to have been a printed using the colour of the eight skilling example together with the cliché for the three skilling kind by mistake.
The only known example of its kind, and a prized possession of collectors such as Count Ferrary, it is thought to be worth $2.33m.
Only a handful of people will ever see, let alone own, the Tre Skilling Yellow. However, examples of the original Tre Skilling Green - though rare - are occasionally available, and one has come up for sale at AB Philea.
It has not been given a guide price, but the reserve is 12,000 Swedish Krona (about $1,600). As examples are increasingly rare, this offers an interesting investment opportunity for collectors.
In the same auction is a cover with two stamps of the same style: a 30 skilling and 24 skilling example, addressed to Montreal, Canada with both Stockholm and London postmarks. It has a reserve price of 10,000 Krona ($1,325).
AB Philia's auction of rare stamps and covers takes place on February 17 in Stockholm.