An 'oil spot' black-glazed bowl of very similar profile is illustrated by R. Krahl, Chinese Ceramics in the Meiyintang Collection, vol.
3 (II), London, 2006, p. 498, no. 1503.
Conical bowls were intended primarily for the drinking of tea. The choice of tea during the Song and Jin periods was a white tea that was whisked to produce a white froth on top. Dark-glazed bowls such the present example became increasingly popular as they showed off the frothy white tea to great advantage.