Indigo

Indigo is a word used for a group of deep blue colors. The name comes from an old dye with the same name. The word can mean the color of the dye, fabrics colored with indigo dye, a color of light, one of the seven colors of the rainbow described by Sir Isaac Newton, or a area on the color wheel. It can include different shades of blue, ultramarine, and blue-green. Since the early days of the web, the word has also been used for some purple and violet shades, based on how the term was used in HTML web page rules. The word comes from the Latin word indicum, which means "Indian," because the dye was first brought to Europe from India.

The Early Modern English word indigo first meant the dye, not the color itself. Indigo is not one of the basic color names that people usually learn first. The earliest known use of indigo as a color name in English was in 1289. Enslaved West Africans knew a great deal about growing indigo, so it became an important crop in the American colonies.

Newton thought of indigo as one of the colors we can see in light, and as one of the seven colors of the rainbow. He placed it between blue and violet. Experts do not agree on exactly where it belongs in the electromagnetic spectrum. Some later scientists have suggested that what Newton called "blue" is what we now call cyan, a blue-green color, and that what he called "indigo" is what we now call blue. Other scholars do not accept this idea.

In the 1980s, programmers made a list of color names for the X Window computer system. It was not based on strict rules. Later, the HTML and CSS rules from the 1990s used "indigo" for a dark purple color. Since then, purple and violet shades have also been linked to the word.

It is hard to name one exact color value for indigo. Because of the Abney effect, a stronger color on the HSV color wheel can look more blue. On the newer CIECAM16 standard, colors around 290° may be called indigo, depending on the person looking at them.

History

Indigo dye is a blue color that comes from several kinds of plants. The best-known is the indigo plant (Indigofera tinctoria), often called "true indigo." Long ago, people grew these plants in places such as East Asia, Egypt, India, Bangladesh and Peru. The earliest direct evidence of indigo use comes from Huaca Prieta in Peru, dating to around 4000 BC. In early Europe, the main source was the woad plant (Isatis tinctoria). Later, "true indigo" took the place of woad as trade routes opened up. Today, plant sources have mostly been replaced by synthetic dyes. Spanish explorers found an American kind of indigo and began growing it in Guatemala.

Indigo also came to North America, where Eliza Lucas is credited with bringing the plant to the southern colonies. However, enslaved West Africans, who were forced to work, were the ones who actually grew the seeds and made the dye. Before the Revolutionary War, indigo was worth more than one-third of the value of exports from the American colonies. Later, Newton named indigo as one of the seven colors of the rainbow after shining sunlight through a prism. Scientists still discuss exactly what Newton meant by the name. Today, modern scientists place indigo between blue and violet.

Shades and variations

Many colors are named after things in nature. Orange, rose, and violet are some of the best-known examples. Indigo gets its name from the plant indigo, which was once used to dye cloth (see also Indigo dye). Indigo dye is a greenish dark blue. It can be made from the leaves of the tropical Indigofera plant, from woad (Isatis tinctoria), or from Chinese indigo (Persicaria tinctoria). Cloth is dipped in the dye many times, and each time it becomes a darker blue. The Cherokee Indians rubbed tallow on their hands while they worked with the dye. In Sa Pa, Vietnam, the leaves are soaked until the water turns blue, and then pickling lime is added. Cloth made from hemp is then dipped in the dye. The pigment indigo matches the web color indigo, but a vat of dye looks closer to midnight blue. Since HTML color names were created during the World Wide Web era, the word "indigo" has also been used for several different colors.

Indigo can describe several shades. "Electric indigo" is a bright, saturated color that falls between traditional indigo and violet. It is the brightest indigo a computer screen can show. In an RGB color space, indigo is mostly blue with some red and no green. In a CMYK color space, it is made from cyan and magenta, with no yellow or black. On a color wheel, indigo can be made by mixing violet with blue. A nearly identical color is electric ultramarine. Electric indigo sits near the middle of the part of the rainbow that is traditionally called indigo. Real spectral colors, however, fall outside the gamut of the sRGB system (see CIE chromaticity diagram). The web color "blue-violet," also called "deep indigo," falls between electric indigo and pigment indigo in brightness. The web color indigo is closer to violet than to the indigo dye it is named after (see § Web era). A "web-safe indigo" is similar to the color wheel indigo but less intense. "Tropical indigo," called añil in a 2005 color guide by Rosa Gallego and Juan Carlos Sanz, is widely popular in the Hispanophone world.

In nature

Male indigobirds are a very dark, metallic blue. The indigo bunting, native to North America, is mostly bright cerulean blue with an indigo head. The related blue grosbeak is, ironically, more indigo than the indigo bunting.

Lactarius indigo is one of the very few mushrooms colored in shades of blue. The eastern indigo snake, Drymarchon couperi, lives in the southeastern United States. It is dark blue or black.

In culture

Indigo shows up in many parts of everyday life. IndiGo is an Indian budget airline that uses an indigo logo and flies only Airbus A320s. Indigo Books and Music also uses an indigo logo. The GameCube was first sold in two colors, one of them called 'Indigo'. In computer graphics lighting, electric indigo is sometimes used as a glow color, possibly because it looks like lavender when mixed with white. In 2008, scientists found that a ripe banana glows bright indigo under a black light. Some insects and birds can see into the ultraviolet because they are tetrachromats. They can use this glow to tell when a banana is ready to eat. The glow comes from a chemical that forms as the green chlorophyll in the peel breaks down. In Marina Warner's novel Indigo (1992), a retelling of Shakespeare's The Tempest, Sycorax makes indigo dye. The French Army chose dark blue indigo during the French Revolution, replacing the white uniforms of the Royal infantry. In 1806, Napoleon decided to bring back white coats because there was a shortage of indigo dye. The shortage was caused by the British continental blockade. The blue was kept, however, and indigo remained the main color of French military coats until 1914.

Indigo also has a place in spiritual life. In West and Central Africa, indigo has been grown for thousands of years. It plays an important role in the traditional beliefs of the Bamileke, Yoruba, Baoulé, Dogon, Fon, and Aja peoples. The spiritualist movement uses electric indigo, which sits between blue and violet on the spectrum. In New Age philosophy, electric indigo stands for the sixth chakra, called Ajna. This chakra is said to include the third eye and is linked to intuition and gnosis, which means spiritual knowledge. Alice A. Bailey used indigo as the "second ray," representing "Love-Wisdom," in her Seven Rays system. This system sorts people into seven metaphysical psychological types. Psychics often link indigo paranormal auras with an interest in religion or deep spirituality and intuition. Indigo children are said to have mostly indigo auras. People with indigo auras are said to prefer jobs such as computer analyst, animal caretaker, and counselor. In Wicca, indigo represents emotion, fluidity, insight, and expressiveness, and it is used for spiritual healing.

Dyes

Indigo dye was used to color denim, giving the original 'blue jeans' their distinctive colour. In 1778, Guatemala was considered one of the world's leading providers of indigo. In Mexico, indigo is known as añil. After silver and cochineal, which makes red, añil was the most important product exported by historical Mexico. In the Philippines, the dye is still used in some places.