Because of their high quality it is often believed that they may have been made at one of the imperial kilns, which were home to the most highly skilled craftsmen.
Karena kualitasnya yang tinggi, seringkali diyakini bahwa mereka mungkin dibuat di salah satu tungku milik kekaisaran, yang merupakan rumah bagi pengrajin-pengrajin Cina yang paling terampil.