Blue pigments

Blue pigments are natural or synthetic materials, usually made from minerals and insoluble with water, used to make the blue colors in painting and other arts. The raw material of the earliest blue pigment was lapis lazuli from mines in Afghanistan, that was refined into the pigment ultramarine. Since the late 18th and 19th century, blue pigments are largely synthetic, manufactured in laboratories and factories. Ultramarine was historically the most prestigious and expensive of blue pigments. It was produced from lapis lazuli, a mineral whose major source was the mines of Sar-e-Sang in what is now northeastern Afghanistan. It was transformed into a pigment by the Afghans beginning in about the 5th century, and exported by caravans to India. It was the most expensive blue used by Renaissance artists. It was often reserved for special purposes, such as painting the robes of the Virgin Mary. Johannes Vermeer used ultramarine only for the most important surfaces where he wanted to attract attention. Pietro Perugino, in his depiction of the Madonna and Child on the Certosa de Pavio Altarpiece, painted only the top level of the Virgin's robes in ultramarine, with azurite beneath. File:Lapis-lazuli hg.jpg|Lapis lazuli in its natural state File:Natural ultramarine pigment.jpg|Natural ultramarine File:The Wilton Diptych (Right).jpg|The [[Wilton Diptych]] (''c.'' 1395-1399)Unknown artist File:Pietro Perugino cat61.jpg|Detail from the [[Certosa di Pavia Altarpiece]] (''c''. 1496-1500)[[Pietro Perugino]] File:Johannes Vermeer - Het melkmeisje - Google Art Project.jpg|''[[The Milkmaid (Vermeer)|Het melkmeisje]]'' (1658)[[Johannes Vermeer]] Ultramarine became more widely used after its successful synthesis in the 19th century, which reduced its price substantially. In 1814, a French chemist named Tassaert observed the spontaneous formation of a blue compound, very similar to ultramarine, in a lime kiln at St. Gobain. In 1824, the Societé pour l'Encouragement d'Industrie offered a prize for the artificial production of the precious color.