Cobalt blue
Cobalt blue in impure forms had long been used in Chinese porcelain, but it was independently discovered as a pure alumina-based pigment by Louis Jacques Thénard in 1802. Commercial production began in France in 1807. The first recorded use of "cobalt blue" as a color name in English was in 1777. The leading world manufacturer of cobalt blue in the 19th century was Benjamin Wegner's Norwegian company Blaafarveværket ("blue colour works" in Dano-Norwegian). Germany was also famous for production, especially the blue colour works ("Blaufarbenwerke") in the Ore Mountains of Saxony.
Phthalocyanine Blue BN
CuPc was first prepared in 1927 by the reaction of copper(I) cyanide and "o"-dibromobenzene, with the apparent intent of preparing phthalonitrile. A couple of years later, workers at Scottish obtained CuPc, FePc, and NiPc from reactions of phthalic anhydride and ammonia. Specifically at the ICI phthalimide plant, a blue contaminant was traced to a by-product formed when the phthalimide reacted with trace amounts of iron from the metal reactor. The chemist took samples of this blue and using sulfuric acid as a solvent, managed to produce a workable pigment. These leads led to the blue pigment sold under the trade name Monastral. Industrial produced commenced in 1935 at ICI, I.G. Farbenindustrie, and DuPont.