The royal families of the Ming Dynasty (1368-1644) favored these chicken cups not only because they used the latest doucai technique, but also for the patterns that signify harmonious country life.

Doucai literally means "colors which fit together", and it was difficult to achieve in the 15th century because the blue color had to be done underglaze, while other colors overglaze, and no satisfactory overglaze blue enamel was available at the time.

Nicholas Chow, deputy chairman of Sotheby's Asia, recounted the first time he came into close contact with a Chenghua chicken cup more than 10 years ago. He was told to remove the cup from the cabinet to show to a client.

Chow tells Chinese media that he was greatly moved by the trust from his boss at the time, and "had never been so nervous" walking about 15 meters across the hall floored with marble.

He calls the piece "the holy grail of Chinese art", and says "there is no more legendary object in the history of Chinese porcelain".

He also points out that it was the most imitated piece of artwork in China, with "tens of thousands, perhaps hundreds of thousands of copies going around in China".

Search for the Chinese characters "ji gang bei" (chicken cup) on Taobao.com, China's premier online marketplace, and you will find more than 20 pages of products for sale, priced from 10 yuan ($1.60) to more than 1,000 yuan.

Some of the online sellers boast that their product is in the "same style as Sotheby's", and entice buyers to "experience 280 million yuan for 18 yuan".

At the Long Museum established by Liu and his wife Wang Wei in 2012, the chicken cup will join other pieces in their private collection, such as an imperial throne from the 18th century, the painted scroll Sketches of Rare Birds by Zhao Ji, an 11th-century emperor of the Song Dynasty (960-1279), and Gongfu Tie, arguably the only surviving calligraphy by Chinese writer Su Shi (1037-1101) of the Northern Song Dynasty (960-1127).

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