An unofficial portrait of Zhu Yuanzhang which looks different from the royal ones on display. [Photo by Jiang Dong/China Daily]

Meanwhile, dozens of unofficial portraits that circulated outside the royal court among the country's commoners presented the emperor with a totally different appearance.

In these paintings, he has an elongated face which features an unusually protruding lower jaw, with high and wide cheekbones, a bulbous nose and a wide mouth to present skeletal disharmony. In some of them, there are black moles all over Zhu's face to make it look impressively worse.

Discussions among historians about which of these representations is more accurate continue unabated.

This puzzling chunk of history is one of the hooks at Harmony of Figures and Spirits, an ongoing exhibition at the National Museum of China, showing dozens of colored ink portraits from its collection of Ming and Qing (1644-1911) dynasty art.

A Qing-era royal portrait which shows Zhu vigorous in the prime of his life is displayed side-by-side with an unofficial Ming-era portrait of the emperor whose dysmorphic face is covered with moles.

Although Zhu favored the many imposingly good-looking portraits, it is said that he might have consented to, and even started, the circulation of the less flattering portraits outside the royal court.