Chinese ceramics often have a reign mark on the base indicating the date the object was made. They can be made up of four to six Chinese characters, in kaishu (normal script) or zhuanshu (archaic seal script). Zhuanshu was developed from bronze inscriptions and stylized into a form of calligraphy. The first two characters of six character reign marks consist of the name of the dynasty, for example Da Qing (Great Qing) followed by the name with which the period was made, for example Kangxi (after the Kangxi emperor) and finally nian zhi (period made). When four characters are used, the title of the dynasty is omitted, e.g Kangxi nian zhi.
Reign marks are commonly framed by a double circle. Painted in underglaze blue but also red, gold and other colours. Overglaze colours popular from Qianlong period onwards (examples on guyuexuan items).
They do not necessarily correspond to the period in which the object was actually made as many give an earlier reign to increase the prestige of the object. The most popularly referred to reigns are those of the Xuande emperor (1425-1435), Chenghua (1465-1487) and Jiajing (1522-1566), all periods of the Ming dynasty.
During the Kangxi period (1662-1722) a ban was enforced on marking non-Imperial ware with reign marks. This led to the appearance of empty double circles and other marks, such as the hare staring at the moon mark, the artemisia leaf and the open lozenge (see below). These were considered symbols of good fortune. Reign marks from earlier periods were also used. By the middle of the reign there is evidence that reign marks were once again being used on non-imperial wares.