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Johann Jacob Diesbach was a Swiss pigment and dye producer known for first synthesising a blue pigment known as Prussian blue, aka iron blue or Berlin blue.
Around 1706 Diesbach was working in the laboratory of Johann Conrad Dippel in Berlin. Using an extract of crushed cochineal insects, iron sulphate and potash to create cochineal red lake, he used potash that was mixed with Dippel's bone oil. The result was a very pale red which he concentrated to purple, later a deep blue. While neither Diesbach nor Dippel knew what exactly happened the formula was the first modern Synthetic pigment, and an important invention, because at that time the alternative blue pigments were either not very successful or affordable for large scale use.
The pigment was first mentioned in a letter, the first of several, from Frisch to the president of the Royal Academy of Sciences, Gottfried Wilhelm Leibniz, dated March 1708. By August 1709, the pigment was being referred to as "Preussisch blau" and by November of that year, as "Berlinisch Blau".