A US 1851 1c blue is to headline a sale of worldwide stamps at Daniel F Kelleher Auctions in Danbury, Connecticut on August 4-6.
The rare lot is valued at $25,000-35,000.
There are only 110 specimens of the stamp known, placing it among the rarest pre-1867 grill issue US postal stamps.
It displays a strong strike of the Boston PAID cancel.
An 1857 Queen Victoria half pence rose block of four is valued at $20,000-30,000.
The lot is a unique example of this rare Canadian issue, which displays a stitch watermark. It's described as being in very fine to extremely fine condition.
Other interesting lots in the sale include an airmail cover sent from Newfoundland to the Scilly Isles in Cornwall in 1930.
It displays a fine example of the 50¢ on 36¢ Columbia Flight overprint and carries an estimate of $7,500-10,000.
The auction house comments: "For the mail's franking, 300 examples of this stamp were printed.
"Forty-eight examples were reserved for mail to be posted at Harbour Grace. Eight examples were given to the captain and navigator (two blocks of four).
The remaining 244 stamps were offered to the public with the proviso that only one example could be purchased by each person."
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