DIA150XH50mm, China

This is bowl for rinsing calligraphy brushes, these type of bowls has this specialised function but at the same time is give an artist design freedom.  Though it can be made of varies material (jade, ivory, horns, enamel, agate), the ceramic version is the most popular.  This is a green glaze Bi Xi most probably from the Shi Wan kiln.