The Blue Penny Stamp is one of the rarest and most valuable postage stamps in the world. Issued in 1847 by the island nation of Mauritius, it features a blue color and depicts the profile of Queen Victoria. Only a few copies are known to exist, making it highly sought after by collectors. The stamp gained fame due to its unique printing error, which resulted in a misalignment of the design. This error, along with its limited quantity, has led to its high market value, with some copies selling for millions of dollars at auctions, solidifying its status in philately.