Jun Blue Pot An opalescent stoneware glaze named after a town in northern China where it was first made in the 11th century. The Jun glaze is related to the celadon glaze, being a feldspathic glaze on a buff body and fired in a reducing atmosphere. The beauty of the jun glaze lies in its fine visual texture and opalescent colour. It looks best on simple forms. Sometimes, patches of purple are sometimes used to add character to the Pot.