The 12 zodiac bronzes were installed around a fountain at the Old Summer Palace, or Yuanmingyuan, the former royal resort of the Qing Dynasty (1644-1911).
It was burned and razed to the ground by the invading French and British forces in 1860.
Numerous relics from the site, including the 12 bronzes, later lost to overseas.
The reemergence of the rat and rabbit heads at a Paris auction in 2009 drew wide attention.
"We realized the importance of (the two heads) in the eyes of the Chinese people, and we said, well, can we do something as an individual, as a family, as a group? If we can buy them, we will give them back to China," says Fran?ois-Henri Pinault.
"Chinese culture has an extraordinary impact on all humanity. It is very important for us to participate in the transmission and preservation of China's cultural heritage."
