BEIJING — Jian, a 42-year-old property developer in the booming southern metropolis of Shenzhen, had acquired just about everything men of his socioeconomic ilk covet: a Mercedes-Benz, a sprawling antique jade collection and a lavishly appointed duplex for his wife and daughter.

It was only natural then, he said, that two years ago he took up another costly pastime: a beguiling 20-year-old art major whose affections run him about $6,100 a month.

Jian, who asked that his full name be withheld lest it endanger his 20-year marriage, cavorts with his young coed in a secret apartment he owns, a price he willingly pays for the modern equivalent of a concubine.

“Keeping a mistress is just like playing golf,” he said. “Both are expensive hobbies.”

As China has shed its chaste Communist mores for the wealth and indulgences of a market-oriented economy, the boom has bred a generation of nouveau-riche lotharios yearning to rival the sexual conquests of their imperial ancestors. Even the Chinese term for mistress — “ernai,” or second wife — harks back to that polygamous tradition of yore.