This is a strikingly beautiful, ancient Chinese seal made of yellow jade from the time of the Tang Dynasty (618-907 AD). It is in wonderfully good condition.
It has a very soothing quality to the touch, and is a pleasure to hold.
Seals have been in use in many different cultures, from Neolithic times to the present day. They were used to convey identity, mark ownership and protect property, in the same way that signature often does today. They were also status symbols. Given the weight and quality of this seal, I suspect it was owned by someone of importance.