Indigo is an organic pigment with a blackish, somewhat dull blue tone. The plants from which indigo can be obtained are found in many parts of the world. The plant that gives it its name, Indigofera tinctoria L., is native to India.
As an artist's pigment, indigo has been found in Roman paintings of the first century AD, in miniatures of the early Middle Ages, and in paintings of all periods of European relay painting. The oldest evidence, however, comes from excavations and has been dated to 3000 BC. Note: Real Indian indigo has a typical intrinsic odor.
Indigo is insoluble in both water and alcohol.
It is suitable for tempera, watercolor, oil, acrylics, dye.