 Connoisseurship in the late Ming period centered on these items of refined artistic taste , which provided work for art dealers and even underground scammers who themselves made imitations and false attributions . The Jesuit Matteo Ricci while staying in Nanjing wrote that Chinese scam artists were ingenious at making forgeries and huge profits . However , there were guides to help the wary new connoisseur ; Liu Tong ( died 1637 ) wrote a book printed in 1635 that told his readers how to spot fake and authentic pieces of art . He revealed that a Xuande era ( 1426 – 1435 ) bronzework could be authenticated by judging its sheen ; porcelain wares from the Yongle era ( 1402 – 1424 ) could be judged authentic by their thickness . 
