Official Kiln Pen Washing Disk, Southern Song Dynasty

This pen washing hold a TL test, the results of certificate indicting 300  years +/_ 60 years

High 8 cm Diameter 12 cm

The Context of bottom written by emperor Qianlong translated to be English as below.

A legacy from Xiu Nei.
Six hundred years old, this fragile vessel is still intact. It’s not a jewel, but it’s authentic and can be mistaken. Could it be that bowls didn’t exist in ancient times? The emperor emphasized the importance of round bowls, with fine lines resembling cracks in ice. Among jade pots, it stands alongside the Qianlong inscription

Note; Xie Nei is a department of manufacture porcelain of the Palace use by emperor usage.