Indigo is a deep color that is close to blue on the color wheel (a primary color in the RGB color space), as are some ultramarine variants based on the older dye of the same name. The word “indigo” comes from the Latin word indicum, meaning “Indian”, as the dye was originally exported to Europe from India. It is traditionally considered a color of the visible spectrum, as well as one of the seven colors of the rainbow: the color between blue and violet; However, the sources differ in their actual position on the electromagnetic spectrum. The first known use of indigo as a color name in English was in 1289.