Cobalt violet was developed in the 1860s as part of the cobalt pigment family expansion. The Impressionists immediately adopted it — their discovery that shadows contain violet and blue rather than grey made a permanent, transparent violet essential to their palette. Monet used it systematically to paint the violet shadows in his series paintings.

Luminous, transparent, and atmospheric. Cobalt violet is the colour of shadows in Impressionist painting — not the grey of academic tradition, but the living violet that the Impressionists observed in natural light. It carries associations of delicacy, sensitivity, and the particular quality of late afternoon light.

The Impressionist revolution in shadow colour — using cobalt violet instead of grey-black — was one of the most controversial aspects of their work when first exhibited. Critics mocked the "violet shadows" as symptoms of eye disease. Today, the violet shadow is so established as truth that it seems obvious — a reminder of how radical careful observation can be.