Indigo

Indigo is a beautiful blue color that comes from a special dye made from plants. Long ago, people in India made this dye and sent it to Europe. The word "indigo" comes from a Latin word meaning "Indian" because of this. At first, the word "indigo" was used for the dye itself, not for the color it made.

The famous scientist Sir Isaac Newton thought of indigo as one of the seven colors of the rainbow. He saw it as the color between blue and violet. But scientists today sometimes disagree about exactly where indigo fits in the colors we see.

In the 1980s, computer experts started using the word "indigo" for a dark purple color in their programs. Because of this, today many people think of both blue and purple shades when they hear the word "indigo".

The exact shade of indigo can be tricky to pin down because how we see color can change. But generally, indigo sits around the 290° mark on modern color standards.

History

Indigo as a dye

Main article: Indigo dye § History

Indigo dye is a beautiful blue color that comes from certain plants. One plant, called Indigofera tinctoria, often called "true indigo," gives the best blue color. Other plants like Japanese indigo, Natal indigo, Guatemalan indigo, Chinese indigo, and woad can also make similar blue colors.

People have used these plants to make blue dye for thousands of years. Evidence of indigo use goes back to around 4000 BC in Peru. The ancient Greeks and Romans knew about indigo, and it was traded along the Silk Road from India.

In Europe, people mainly used a plant called woad for blue dye until better trade routes brought true indigo from other places. Explorers found indigo plants in the Americas and began growing them in places like Guatemala. In North America, indigo grew well along the coast and became an important crop, especially in the southern colonies.

Isaac Newton's classification of indigo as a spectral color

Isaac Newton, a famous scientist, named seven colors in the rainbow, including indigo. He discovered this by passing sunlight through a prism, which split the light into different colors. Newton chose seven colors and linked them to music notes. He called one of these colors indigo.

Some scientists later said that what Newton called indigo might actually look more like blue to us today. Others still agree that indigo is a special color between blue and violet. Even though there is some debate, indigo remains one of the traditional rainbow colors, remembered with phrases like "Roy G. Biv."

1800s

In the 1800s, scientists and artists continued to describe the color indigo. Some said it was a deep blue, while others thought it was closer to violet. Books and paintings helped people understand and use this beautiful color.

Modern spectral classification

Today, scientists often place indigo in the range of blue and violet colors on the spectrum of light. However, not everyone agrees exactly where indigo fits, and the color can look different depending on how it is made or seen.

Web era

Origin of "Indigo" as a name for purple in web pages

In the late 20th century, computer experts created lists of colors for screens and websites. They called one dark purple color "indigo," even though it was not the traditional blue indigo. This mistake made many people think of indigo as a purple color on computers and the internet.

Crayola crayon colors

The Crayola company made crayons called "indigo" starting in 1999. These crayons show different shades of blue and purple, showing how the color name has changed over time.

Distinction among tones of indigo

Like many other colors such as orange, rose, and violet, indigo gets its name from a plant once used for dyeing cloth. This plant is called indigo (see also Indigo dye).

The color we call indigo can look different depending on how it is used. The actual dye made from the indigo plant is a dark blue color. When this dye is used in a special way, it can create even darker shades on fabric. There are also brighter versions of indigo, like "electric indigo," which appears very bright on computer screens. These different shades show how versatile the color indigo can be.

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 species of mushrooms colored in tones of blue. The eastern indigo snake, Drymarchon couperi, of the southeastern United States, is a dark blue/black.

Indigo bunting

An upturned Lactarius indigo mushroom

Eastern indigo snake

In culture

Business

IndiGo is an Indian budget airline that uses an indigo logo and only flies Airbus A320s. Indigo Books and Music also uses an indigo logo and sometimes calls the color “blue” in ads. The GameCube video game console was first sold in two colors, one called “Indigo,” with matching controllers.

Computer graphics

Electric indigo is sometimes used to make glowing effects in computer graphics lighting. This is because it can look like it changes from indigo to lavender when mixed with white.

Dyes

Indigo dye was used to color denim, giving blue jeans their special blue look. The original Postal Worker uniform had indigo dye because it didn’t wash out when wet. Guatemala was a major source of indigo by 1778. In Mexico, indigo is called añil. After silver and cochineal for red, añil was an important product Mexico exported. People in the Philippines still use añil mixed with vinegar to treat mumps.

Food

In 2008, scientists found that when a banana ripens, it glows bright indigo under a black light. Some animals can see this because they can see ultraviolet light. This glow happens because a chemical forms as the green chlorophyll in the banana peel breaks down.

Literature

Marina Warner’s novel Indigo (1992) retells Shakespeare’s The Tempest and includes the making of indigo dye.

Military

The French Army started wearing dark blue indigo uniforms during the French Revolution to replace the old white ones. Later, Napoleon wanted to go back to white because there wasn’t enough indigo dye. But blue was more practical, so they kept wearing indigo until 1914.

Spirituality

In spiritual ideas, electric indigo is used because it sits between blue and violet on the color spectrum. In West and Central Africa, indigo has been grown for thousands of years and is important in the beliefs of the Bamileke, Yoruba, Baoulé, Dogon, Fon, and Aja peoples. In New Age thinking, electric indigo stands for the sixth chakra called Ajna, linked to the third eye and ideas about intuition and inner knowing. Some people think those with indigo auras are interested in religion or deep spirituality. In Wicca, indigo stands for feelings, flow, understanding, and expression, and is used for healing.