Indigo is a deep color close to the color wheel blue, as well as to some variants of ultramarine, based on the ancient dye of the same name. The word "indigo" comes from the Latin word indicum, meaning "Indian", as the plant-based dye was originally exported to Europe from India. Here are some key points about indigo:
- Indigo is a natural dye extracted from the leaves of plants in the genus Indigofera, which grow in subtropical and tropical locations around the world.
- The dye is a dark blue crystalline powder that is insoluble in water, alcohol, or ether, but soluble in DMSO, chloroform, nitrobenzene, and concentrated sulfuric acid.
- Indigo is used as a dye for cotton yarn, mainly used in the production of denim cloth suitable for blue jeans.
- The color "electric indigo" is a bright and saturated color between the traditional indigo and violet. This is the brightest color indigo that can be approximated on a computer screen; it is a color located between the (primary) blue and the color violet of the RGB color wheel.
- Indigo is a legume, which means that it can fix nitrogen in the soil, and therefore, its used as a rotation crop in agriculture to improve soil quality.
Today, the color “indigo” refers to a blue-purple color that many people can’t actually distinguish from blue or purple. Experts say that Newton only put indigo in the rainbow because he wanted seven colors, and indigo was an extremely valuable commodity at the time.
