Bowl, Yuan dynasty (1279–1368). Blue glaze stoneware, height 8,5 cm, depth Ø 18,7 cm. National Gallery of Prague, Vu 2737.

While porcelain vessels with monochrome glazes aesthetically follow the famous Song monochrome wares, in technical terms these glazes were quite innovative. Blue shades of different intensity were achieved by means of cobalt as a colouring agent. This bowl of a noble shape and glaze shade is also decorated with a dark edge and a randomly placed spot of darker colour, which was done by adding a tiny amount of another colouring agent during the firing process.