Prussian blue
![Vincent van Gogh's Starry Night uses Prussian and Cerulean blue pigments.](/Images/godic/202502/01/Vincent_van_Gogh_Starry_Night2816.jpg")
![Prussian blue stain](/Images/godic/202502/01/Intra-alveolar_hemosiderin_deposition_-_Prussian_blue_stain2816.jpg")
![Ferricyanide ion, used to make Turnbull's blue](/Images/godic/202502/01/HexacyanidoferratIII_2.svg2816.png")
![Prussian blue pigment](/Images/godic/202502/01/Pigment_Berliner_Blau2816.JPG")
Prussian blue is a dark blue pigment with the idealized chemical formula Fe
7(CN)
18. To better understand the binding situation in this complex compound the formula can also be written as Fe
4[Fe(CN)
6]
3 · xH
2O. Another name for the color is Berlin blue or, in painting, Parisian or Paris blue. Turnbull's blue is the same substance, but is made from different reagents, and its slightly different color stems from different impurities.