What is the highest price ever paid for a stamp?

As of October 2023, the highest price ever paid for a stamp is $9.48 million. This record was set in June 2021 when a unique copy of the 1856 British Guiana one-cent magenta was sold at auction. The stamp is notable for its rarity, having been issued in limited quantities and bearing unique markings. Its sale underscored the continued interest and investment in philately among collectors.