Ewer with motif of grapes in cartouches

The ewer with the motif of grapes in cartouches, painted in underglaze cobalt blue, is one of the most precious types of Chinese porcelain. In the Yongle (1402–1424) and Xuande (1425–1435) periods of the Ming dynasty (1368–1644), the pigment known as Mohammedan blue was used to paint porcelain; this pigment was obtained in central Asia by Chinese explorers during their historically unprecedented travels. Unlike other types of cobalt blue, Mohammedan blue creates small darker-hued crystals in the painted pattern after firing, which was highly prized by later collectors of Chinese porcelain.