Girls from the Tuareg tribe wearing traditional dry-dyed indigo veils.  Indigo is a plant-based, metallic dye, and is so richly beaten into the fabric that it rubs off onto their skin, turning them a deep blue-violet.  “Tuareg” means “Blue People”, and indigo is so precious that the tribespeople wear their stains with as much pomp as if their skin were shining with diamond dust.

Young Tuareg girls, Mali (by Mark William Brunner)