. The invention of smalt is sometimes credited to a Bohemian glassmaker named Christoph Schurer, around 1540-1560. Cobalt was, however, used as a pigment in Central Asia from 13th century. A fragment of a mud painting in the ancient Tangut city of Khara-Khoto has been found to contain smalt, judged to be dated between 11th to 13th century. Footnotes… (More on Smalt)