A staff member shows the rare Ru guanyao brush washer from Northern Song Dynasty (960-1127) during Sotheby's 2017 Hong Kong's autumn sale, in Hong Kong on Tuesday. /Chinanews Photo

The rare Ru guanyao brush washer set a new world auction record for Chinese ceramics when it sold for 294.3 million HK dollars (about 37.7 million US dollars) after a 20 minute bidding battle. /Chinanews Photo

This Song Dynasty Ru guanyao brush washer has a diameter of 13 centimeters, and is an elaborate piece from that time. It sold for record amounts at auction because so few of the same brush washers still exist. /Chinanews Photo