A mint Russia 1857 first issue imperforate, 10k brown & blue is the headline lot of Daniel F Kelleher's Flagship US, British and Worldwide Stamps and Postal History in New York on October 25-26.
It carries an estimate of $50,000-70,000.
The stamp was the first to be sold in imperial Russia. Unused copies of the issue are extremely rare, with the present example regarded as among the finest.
The lot is lightly hinged with strong margins and is one of very few to retain its original gum.
An Iranian 1876 1k Coat of Arms error stamp is another highlight, with a valuation of $15,000-20,000.
Kelleher describes it as: "Without any doubt, one of the Crown Jewels of the Iranian philately."
It was issued by the Indian Post Office - which operated in Iran under the British throughout the mid 19th and early 20th centuries - and was mistakenly printed yellow.
A collection of Indian Post Office in Iran covers is to cross the block at Spink tomorrow, with an 1857 Naval Dubash cover providing the top lot.
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