It is one of the Chinese names for seals, referring to both official and private seals before the Qin dynasty (221 BC), but only to emperors', empresses' and princes' seals after Qin. Other officials' seals were called Yin then. Empresses' seals were also called Bao in and after the Tang dynasty (618-907).[1]
Official seal
In ancient China, official seals, as a kind of certificate, were offered to the officials at the time when they were appointed to the posts. So, their seals vary in size, material and shape with their posts. Different ages have different styles. The Qin and Han seal characters were made by carving or casting; the Sui and Tang characters were carved in low relief; the Song seals have date marks; and the Jin, Yuan, Ming and Qing seal characters are mostly carved in Jiudie seal script with multiple and parallel strokes. Furthermore, seal knobs also vary with ages.[1]
Private seal
In ancient times, private seals were taken as a kind of erupt of a person's identity. They could have different contents for different functions, such as seals of a person's name, a studio name, an auspicious phrase, a zodiac animal, an idiom and a collection appraisal mark.[1]
Red legend and white legend
Seal characters carved in relief are called the red or positive legend as they are in red when being stamped on paper; otherwise they are called the white or negative legend. The seal shown at the bottom corner on the right of this page is a good example with two legends on one seal. The character on the right is the white legend and the one on the left is the red.[1]
Design seal
Seals carved with a design of figures, creatures, vehicles and architectures belong to a special type of private seals. It was popularly used as auspicious wishes or design mould stamps in the Warring States period and Han and Jin dynasties (475 BC—AD 420).[1]
Horse brand stamp
Being a special type of ancient Chinese seals, horse brand stamp looks similar to ordinary seals but was only used to brand a horse for identification .[1]
Seal knob
Most of ancient Chinese seals have a pierced knob in shape of a nose, an arched tile, a trapezoid, a serpent, a turtle, a camel or a horse on the top for handling and stringing. It could also be regarded as rank marks of official seals. Private seal knobs have more varieties.[1]
Seal inscription
In addition to the seal characters, some seals also have inscriptions on the top and sides. The Sui, Tang, Song and Yuan (581-1368) seal inscriptions usually give the date and content explanation. And the Ming and Qing (1368-1911) ones have more contents as an art component of the seals.[1]
Clay seal
It is a piece of clay pressed with certain patterns or characters and fixed across an opening of a packet or envelope. During the period from Warring States period to Jin dynasty (475 BC—AD 420), the formal and official writings written on bamboo and wooden strips were tied up by a rope and sealed with a piece of pressed clay across the opening. But this system gradually declined in the Southern and Northern (Eastern Han dynasty 25-220)[1]
