The official seal of the Kangxi Emperor smashed its estimate at Sotheby's Hong Kong on April 6.
The lot, which the auction house described as "the most important piece of Chinese history ever to come to auction", realised $11.9m in the Kangxi - Emperorship and Power sale.
It achieved an increase of 85.9% on a $6.4m valuation.
The Kangxi Emperor (1654-1722) was the fourth ruler of the Qing dynasty (1644-1912) and China's longest serving emperor.
He is credited with establishing national stability after the turbulence of the preceding centuries.
His seal is made from sandalwood and carved into the shape of a mythical creature.
It reads "Jingtian Qinmin", which means "to respect heaven and diligently serve the people" - the guiding principle of the Chinese imperial system.
As Nicolas Chow, deputy chairman of Sotheby's Asia, explained: "This seal is emblematic of the Mandate of Heaven, which has legitimised the authority of rulers in China since the dawn of recorded history.
"This almighty principle was also the single guiding light for the Kangxi Emperor, China's longest reigning emperor, who is credited for completing the conquest of China, anchoring the Qing dynasty and ushering in a long period of great prosperity and peace."
Another seal belonging to the Kangxi Emperor realised $6.3m in the auction.
The record for any Chinese imperial seal is $15.6m, set for a white jade example made for the Qianlong Emperor (1711-1799) at Sotheby's in 2010.
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