Cobalt gives ceramics a very elegant dark blue colour. The five Chinese dynasties—Tang, Song, Yuan, Ming, and Qing, from the 7th to 20th centuries—witnessed the origin, boom and bust of blue-decorated ceramics, known as blue Sancai and blue-and-white porcelains. Blue Sancai is a kind of Sancai (lead-glazed) ware with cobalt-blue decoration, either alone or in combination with other colours, usually white, yellow and green. The archetypal Chinese blue-and-white porcelain is a porcelain decorated with underglaze cobalt pigment(s) and covered with a transparent lime glaze. A large volume of archaeological research has discussed the kiln sites, production organisation, main users, periods of popularity, distribution, materials and technologies etc., and many studies have included scientific analyses. This paper reviews the production and use of blue-decorated ceramics and the technology of cobalt materials in order to summarise the use of cobalt on Chinese ceramics.