Nick Salter, who runs Philatelic Investor, a British Web site that provides financial advice to stamp collectors, confirmed that the Cultural Revolution era was in particular demand. “Very broadly,” Mr. Salter said, “the Chinese appear to be buying as collectors, whereas Westerners are more likely to be buying for investment, in the anticipation that they can sell on into the Chinese market at a later date.”

China’s first stamps, the “Large Dragons,” were printed in Shanghai in 1878 when the city was controlled by foreigners. The stamps were inscribed “China” in Latin letters and Chinese characters, and denominated in candareens, a unit of weight then used to describe a unit of imperial currency.

A set of the three basic stamps from this first issue would sell at auction now for less than $1,000, Mr. Schneider said. In contrast, the most sought-after stamps from the Qing Dynasty era, which lasted until 1911 — the 1897 “Red Revenues” — can sell for hundreds of thousands of dollars.

In 1897, China changed its currency: but new stamps ordered from Japan failed to arrive on time, Mr. Schneider said, so the government overprinted some unissued “3 cent” Red Revenue stamps with the new currency.

One of this series, called the “Small One Dollar” because a “1 dollar” value is also marked in smaller type, is today acknowledged as the rarest of all regular-issued Chinese stamps. Only 32 recorded copies are in existence, one of which sold in January at Interasia for 5.52 million Hong Kong dollars, a world record for a Chinese stamp.

Collecting stamps dating from the Qing Dynasty tends to appeal to more traditional, “classic stamp” collectors, Mr. Schneider said, and “many often require a little bit more expertise and knowledge.”