Collectors of the famed CIA Invert have two opportunities to bid on the error stamp next month.
A single example with a seldom seen white stripe will auction at Cherrystone with a $14,000 opening bid at the September 11-closing auction.
Just 95 examples of the 1979 inverted $1 Rush Lamp, as it is more formally known, are believed to exist, with just eight featuring the white stripe.
The auction will also feature a rare block of four, without the white stripe - one of just three known such blocks. A block of four previously sold for $60,000 in 2004. This current block has an opening bid of $57,500, with the auction house stating that these blocks are particularly undervalued.
Both lots have never been hinged and are in "post office fresh" condition.
The CIA Invert features a lamp holder and text that is inverted relative to the flame. The stamp was the first major invert error on a stamp since the 1962 Dag Hammarskjöld.
The stamp takes its name from the CIA agent who bought the only sheet of the error stamp on a routine run to the local post office in McLean, Virginia to re-stock the agency's stamp supply.
On realising the error and potential value of what he had bought, the agent and his colleagues kept one stamp each and sold the remainder of the sheet to a local stamp dealer.
The government, also realising their value, attempted to recover the sold stamps, but was unable to as the agent had bought them legally.
However, the CIA forced the employees to return the stamps they had kept, with rumours circulating that those who had refused were later fired.
We will bring you full results of the auction next month.