JP: 呉須/ごす

A natural mineral which consists mainly of cobalt oxide used in cobalt-blue pigment. Most of them were imported from mainly China. They were quite precious, rare and expensive in Japan. It used to be used for sometsuke (blue and white painting) on ceramic products, but nowadays, an artificial cobalt pigment is used in place of gosu.

Cobalt blueGosuPigmentSometsuke