The Chinese term doucai means 'joined colours' or 'contrasting colours'. The production of doucai wares was technically difficult and required two firings: the design's outline is painted in underglaze blue, the piece is glazed, then fired at a high temperature. The outlines were then coloured in with red, yellow, green and aubergine overglaze enamels, and the object was fired again at a lower temperature.Doucai enameling was invented in the early fifteenth century and perfected during the reign of the emperor Chenghua (1465-87). Very little doucai was produced in the middle and late Ming dynasty, though some pieces do survive - mostly copies of Chenghua period pieces. However, the technique was revived in the eighteenth century. The later wares are technically finer: the porcelain is a purer white, and the enamels more clear and with a broader range of colour. The Chenghua wares are more highly valued by connoisseurs for their tactility and subtle charm.This vase, which dates to the reign of Emperor Yongzheng (AD 1723-35), is a very good example of the technical perfection in later doucai wares. The main design comprises green, yellow and mauve dragon medallions. The dragons are five-clawed, whose use was restricted to the emperor. Auspicious Buddhist emblems decorate the shoulder of the vase.