The Singh Twins painting of the story of indigo, showing both its value as well as the suffering caused[/caption] NATURAL INDIGO DYE: Blue is the color of the sky and the sea. It is the color of the sapphire and the tanzanite. It is a color we take so much for granted when we wear our denim and fleece that we forget that at one time, it was worth its weight in gold, worn only by the richest and royal. Indeed it was called Blue Gold. It also has a turbulent history associated with famine, slavery, and human suffering.