This essay reconsiders the story of a pigment. Prussian blue, discovered at the beginning of the eighteenth century, is often described as a revolutionary colour that instantly transformed painters’ palettes and practices. Grounded in a ‘thick description’ of the pigment's history in Paris, this article challenges the legendary account of Prussian blue through a more granular retelling of its development. It reconstructs the chaîne opératoire of Prussian blue through the laboratories of chemists, the factories of manufacturers, the shops of colour merchants, and the studios of artists. Emphasizing the intersections between the worlds of art, chemistry, and commerce, this essay points to the pigment's transformative impact in the larger history of artists’ materials as a scientifically created and commercially marketed product. Shedding new light on the history of Prussian blue, this study also offers an interdisciplinary methodological approach to artists’ materials through art history, social history, and conservation science.