There are several varieties of Red Revenue stamps, with the "Small One Dollar" being the rarest and most valuable. It has been called "China's rarest regularly issued stamp". In a 2013 Hong Kong auction, a single stamp was sold for HK$6.9 million.[3] Another was sold in a 2013 Beijing auction for 7.22 million yuan. A block of four, considered the "crown jewel" of Chinese philately, was reportedly sold in 2009, together with a different stamp, for 120 million yuan (US$18.8 million).[4]