London auction houses are selling 16 million pounds ($26 million) of Asian art this week as a record number of buyers from mainland China flock to Britain.

The collectors have been attracted by gallery shows and sales, with the star lot an Imperial jade seal that last night fetched 3.6 million pounds, six times its top estimate.

“We’ve seen a really aggressive push from mainland Chinese collectors during the last season of sales,” Nicolas Chow, Sotheby’s international head of Chinese ceramics and works of art, said in an interview. “What is new is that they’re buying things at the very highest level,” he said. The seal was “like holding Imperial power in the palm of your hand.”

Newly wealthy Chinese are keen to acquire high quality objects from their heritage, particularly when associated with Emperors from the Qing and Ming dynasties, said dealers.

With mainland collectors and traders needing a formal invitation to travel to the U.K., dealers said that more than ever were in town for in the 12th annual Asian Art in London event, running through Nov. 7. Christie’s International sent invites to 210 mainland Chinese, with Sotheby’s writing to a similar number as demand and prices rise for Asian antiques.

The five-inch-by-five-inch seal, carved with a pair of dragons, was included in Sotheby’s 261-lot auction. The piece was made for the 55th year of the reign of Emperor Qianlong, who ruled China from 1736 to 1795. The seal, from a European private collection, was fought for by eight bidders and was sold to an anonymous dealer in the room, said Sotheby’s.