Now visitors can see for themselves the scarlet hair bands, pink faces, scarlet lips, purple robes and pants of the warriors. [Photo/Xinhua]

No written records have been found on the production of Han purple and Han blue. The rare paints were used on pottery, murals and tomb artifacts during the Western Zhou period (1046-771 BC) until the end of the Han dynasty (AD 220). However, since then they have disappeared.

"Synthetic barium copper silicate is made from azurite, barite, quartz and other minerals heated together in temperature around 1,000 degrees Celsius. We can try to make the pigments in labs, but it is a very difficult technique, even for today," Xia says.

The paints were bound to the surface with lacquer, symbolizing luxury and status. They were used by emperors and noble families.

Overall, in the Qinshihuang mausoleum, there are more than ten colors for the Terracottas, including scarlet, pink, green, jujube red, azure, pink-purple and reddish brown.

"The colors on the surface of Terracotta Warriors show vibrancy and liveliness in the emotions of the Qin people. It is definitely not one of sadness or low spirit," says Yuan Zhongyi, a senior archaeologist and retired curator of the museum.