Notably, the character for knob (niǔ) is sometimes written as 钮 in simplified Chinese (with 钅), and 鈕 in traditional Chinese (with 金), instead of using the nowadays more commonly used 纽 (with 纟) or 紐 (with 糹) respectively, mainly because in the very early periods governmental seals were mainly made of metal.

But in the Song dynasty, especially the Southern Song dynasty, due to the rise of artist groups and scholars and the prosperity of the economy, common people also needed to express or identify themselves, and private seals became more and more popular.

In the late Yuan dynasty famous specialized seal artists or craftsmen appeared.

In the mid and late Ming dynasty, seal sculpture became truly popular among artists and scholars for the first time.

For many private seals, such as those of artists, calligraphers, and painters, a wide range of subjects are depicted.

In ancient Chinese this is called qiao diao (巧雕; roughly, "sculpture of cleverness").