White porcelain rounded square dish with pale blue glaze. “Kō”

Pale blue porcelain

Pale-blue celadon porcelain (seihakuji, known as qingbai in Chinese) is made from porcelain clay derived from white stone. The porcelain is bisque fired and then covered with a glaze containing minute amounts of iron, which turns a blue tint when fired. Celadon originated in China. White porcelain made with a glaze that turns transparent when fired is called hakuji (“white porcelain”), while pieces made from porcelain clay containing iron and coated in a glaze that turns a bluish-green when fired is called seiji (“celadon” or “green ware”).