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Prussian blue Prus·sian blue (prŭsh'ən)
See Berlin blue.
any of several deep-blue pigments that are composed of complex iron cyanides and hence called iron blues. The most common of these pigments are Prussian, Chinese, Milori, and toning blue. Prussian blue has a reddish tint and is used almost exclusively in paints, enamels, and lacquers; Chinese blue is very dark, with a greenish tint, and is favoured for use in printing inks; Milori blue has a reddish tint; toning blue is dull, with a strong red tone. All these pigments are chemically similar, differences in shade arising from variations in particle size and details of the manufacturing process.