The color word blue

Think you know what the word blue means? While in English it’s a broad word used to describe everything from shimmering waters to depressed feelings, but a look at the origin of the word blue reveals it didn’t mean the color blue at all.

To learn the origin of the word blue, word experts looked back through the millennia to the language of the Proto-Indo-Europeans, an ancient culture rooted in Central Asia and Eastern Europe. These people used the word bhle- to describe something that was light-colored. Some scholars suspect bhle- may have even meant “yellow.”

The Origin Of The Word Blue Evolved Into Several Words For Color

As people and their languages became more diverse, so did the words based on bhle-. Here’s a short list of the terms spawned by that simple four-letter word:

belyi – Russian for white
blawr – Welsh for gray
blanc – French for white or blank
blavo – Old Spanish for yellowish-gray
flavus – Latin for yellow
phalos – Greek for white

For modern English speakers, the word blue came from the Old English bleu, which was borrowed from Old French, the language spoken by the people of northern France during the Dark Ages.

Some Languages Uses The Same Word For Blue And Green

An interesting trivia tidbit about the color blue is that many languages don’t use separate words for blue and green. Koreans, for instance, use the word pureu-da to describe both colors. Likewise the Thai word khiaw usually means green but can represent blue when describing the sky or the ocean.

More What’s Behind the Color Name

Blue
Clockwise, from top left: Police officer on duty; Tiles of the Sheikh Lotfollah Mosque, Iran; Red-legged honeycreeper; Copper(II) sulfate; Sea at the Marshall Islands; Planet Earth.
Spectral coordinates
Wavelength	approx. 450–495 nm
Frequency	~670–610 THz
Colour coordinates
Hex triplet	#0000FF
sRGBB (r, g, b)	(0, 0, 255)
HSV (h, s, v)	(240°, 100%, 100%)
CIELChuv (L, C, h)	(32, 131, 266°)
Source	HTML/CSS[1]
B: Normalized to [0–255] (byte) H: Normalized to [0–100] (hundred)

Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model.^[2] It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when observing light with a dominant wavelength between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective.

Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli was used in ancient Egypt for jewellery and ornament and later, in the Renaissance, to make the pigment ultramarine, the most expensive of all pigments. In the eighth century Chinese artists used cobalt blue to colour fine blue and white porcelain. In the Middle Ages, European artists used it in the windows of cathedrals. Europeans wore clothing coloured with the vegetable dye woad until it was replaced by the finer indigo from America. In the 19th century, synthetic blue dyes and pigments gradually replaced organic dyes and mineral pigments. Dark blue became a common colour for military uniforms and later, in the late 20th century, for business suits. Because blue has commonly been associated with harmony, it was chosen as the colour of the flags of the United Nations and the European Union.^[3]

Surveys in the US and Europe show that blue is the colour most commonly associated with harmony, faithfulness, confidence, distance, infinity, the imagination, cold, and occasionally with sadness.^[4] In US and European public opinion polls it is the most popular colour, chosen by almost half of both men and women as their favourite colour.^[5] The same surveys also showed that blue was the colour most associated with the masculine, just ahead of black, and was also the colour most associated with intelligence, knowledge, calm, and concentration.^[4]

Etymology and linguistics

The modern English word blue comes from Middle English bleu or blewe, from the Old French bleu, a word of Germanic origin, related to the Old High German word blao (meaning ‘shimmering, lustrous’).^[6] In heraldry, the word azure is used for blue.^[7]

In Russian, Spanish^[8] and some other languages, there is no single word for blue, but rather different words for light blue (голубой, goluboj; Celeste) and dark blue (синий, sinij; Azul). See Colour term.

Several languages, including Japanese and Lakota Sioux, use the same word to describe blue and green. For example, in Vietnamese, the colour of both tree leaves and the sky is xanh. In Japanese, the word for blue (青, ao) is often used for colours that English speakers would refer to as green, such as the colour of a traffic signal meaning «go». In Lakota, the word tȟó is used for both blue and green, the two colours not being distinguished in older Lakota. (For more on this subject, see Distinguishing blue from green in language.)

Linguistic research indicates that languages do not begin by having a word for the colour blue.^[9] Colour names often developed individually in natural languages, typically beginning with black and white (or dark and light), and then adding red, and only much later – usually as the last main category of colour accepted in a language – adding the colour blue, probably when blue pigments could be manufactured reliably in the culture using that language.^[9]

Optics and colour theory

Human eyes perceive blue when observing light which has a dominant wavelength of roughly 450–495 nanometres.^[10] Blues with a higher frequency and thus a shorter wavelength gradually look more violet, while those with a lower frequency and a longer wavelength gradually appear more green. Pure blue, in the middle, has a wavelength of 470 nanometres.

Isaac Newton included blue as one of the seven colours in his first description the visible spectrum.^[11] He chose seven colours because that was the number of notes in the musical scale, which he believed was related to the optical spectrum. He included indigo, the hue between blue and violet, as one of the separate colours, though today it is usually considered a hue of blue.^[12]

In painting and traditional colour theory, blue is one of the three primary colours of pigments (red, yellow, blue), which can be mixed to form a wide gamut of colours. Red and blue mixed together form violet, blue and yellow together form green. Mixing all three primary colours together produces a dark brown. From the Renaissance onward, painters used this system to create their colours. (See RYB colour model.)

The RYB model was used for colour printing by Jacob Christoph Le Blon as early as 1725. Later, printers discovered that more accurate colours could be created by using combinations of cyan, magenta, yellow, and black ink, put onto separate inked plates and then overlaid one at a time onto paper. This method could produce almost all the colours in the spectrum with reasonable accuracy.

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  Additive colour mixing. The combination of primary colours produces secondary colours where two overlap; the combination red, green, and blue each in full intensity makes white.

On the HSV colour wheel, the complement of blue is yellow; that is, a colour corresponding to an equal mixture of red and green light. On a colour wheel based on traditional colour theory (RYB) where blue was considered a primary colour, its complementary colour is considered to be orange (based on the Munsell colour wheel).^[13]

Lasers emitting in the blue region of the spectrum became widely available to the public in 2010 with the release of inexpensive high-powered 445–447 nm laser diode technology.^[14] Previously the blue wavelengths were accessible only through DPSS which are comparatively expensive and inefficient, but still widely used by scientists for applications including optogenetics, Raman spectroscopy, and particle image velocimetry, due to their superior beam quality.^[15] Blue gas lasers are also still commonly used for holography, DNA sequencing, optical pumping, among other scientific and medical applications.

Shades and variations

Blue is the colour of light between violet and cyan on the visible spectrum. Hues of blue include indigo and ultramarine, closer to violet; pure blue, without any mixture of other colours; Azure, which is a lighter shade of blue, similar to the colour of the sky; Cyan, which is midway in the spectrum between blue and green, and the other blue-greens such as turquoise, teal, and aquamarine.

Blue also varies in shade or tint; darker shades of blue contain black or grey, while lighter tints contain white. Darker shades of blue include ultramarine, cobalt blue, navy blue, and Prussian blue; while lighter tints include sky blue, azure, and Egyptian blue. (For a more complete list see the List of colours).

As a structural colour

In nature, many blue phenomena arise from structural colouration, the result of interference between reflections from two or more surfaces of thin films, combined with refraction as light enters and exits such films. The geometry then determines that at certain angles, the light reflected from both surfaces interferes constructively, while at other angles, the light interferes destructively. Diverse colours therefore appear despite the absence of colourants.^[16]

Colourants

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Artificial blues

Egyptian blue, the first artificial pigment, was produced in the third millennium BC in Ancient Egypt. It is produced by heating pulverized sand, copper, and natron. It was used in tomb paintings and funereal objects to protect the dead in their afterlife. Prior to the 1700s, blue colourants for artwork were mainly based on lapis lazuli and the related mineral ultramarine. A breakthrough occurred in 1709 when German druggist and pigment maker Johann Jacob Diesbach discovered Prussian blue. The new blue arose from experiments involving heating dried blood with iron sulphides and was initially called Berliner Blau. By 1710 it was being used by the French painter Antoine Watteau, and later his successor Nicolas Lancret. It became immensely popular for the manufacture of wallpaper, and in the 19th century was widely used by French impressionist painters.^[17] Beginning in the 1820s, Prussian blue was imported into Japan through the port of Nagasaki. It was called bero-ai, or Berlin blue, and it became popular because it did not fade like traditional Japanese blue pigment, ai-gami, made from the dayflower. Prussian blue was used by both Hokusai, in his wave paintings, and Hiroshige.^[18]

In 1799 a French chemist, Louis Jacques Thénard, made a synthetic cobalt blue pigment which became immensely popular with painters.

In 1824 the Societé pour l’Encouragement d’Industrie in France offered a prize for the invention of an artificial ultramarine which could rival the natural colour made from lapis lazuli. The prize was won in 1826 by a chemist named Jean Baptiste Guimet, but he refused to reveal the formula of his colour. In 1828, another scientist, Christian Gmelin then a professor of chemistry in Tübingen, found the process and published his formula. This was the beginning of new industry to manufacture artificial ultramarine, which eventually almost completely replaced the natural product.^[19]

In 1878 German chemists synthesized indigo. This product rapidly replaced natural indigo, wiping out vast farms growing indigo. It is now the blue of blue jeans. As the pace of organic chemistry accelerated, a succession of synthetic blue dyes were discovered including Indanthrone blue, which had even greater resistance to fading during washing or in the sun, and copper phthalocyanine.

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  The Blue Boy (1770), featuring lapis lazuli, indigo, and cobalt colourants,^[20]

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  A synthetic indigo dye factory in Germany in 1890.

Dyes for textiles and food

Blue dyes are organic compounds, both synthetic and natural.^[21] Woad and true indigo were once used but since the early 1900s, all indigo is synthetic. Produced on an industrial scale, indigo is the blue of blue jeans.

For food, the triarylmethane dye Brilliant blue FCF is used for candies. The search continues for stable, natural blue dyes suitable for the food industry.^[21]

Pigments for painting and glass

Blue pigments were once produced from minerals, especially lapis lazuli and its close relative ultramarine. These minerals were crushed, ground into powder, and then mixed with a quick-drying binding agent, such as egg yolk (tempera painting); or with a slow-drying oil, such as linseed oil, for oil painting. Two inorganic but synthetic blue pigments are cerulean blue (primarily cobalt(II) stanate: Co₂SnO₄) and Prussian blue (milori blue: primarily Fe₇(CN)₁₈). The chromophore in blue glass and glazes is cobalt(II). Diverse cobalt(II) salts such as cobalt carbonate or cobalt(II) aluminate are mixed with the silica prior to firing. The cobalt occupies sites otherwise filled with silicon.

Inks

Methyl blue is the dominant blue pigment in inks used in pens.^[22] Blueprinting involves the production of Prussian blue in situ.

Inorganic compounds

Certain metal ions characteristically form blue solutions or blue salts. Of some practical importance, cobalt is used to make the deep blue glazes and glasses. It substitutes for silicon or aluminum ions in these materials. Cobalt is the blue chromophore in stained glass windows, such as those in Gothic cathedrals and in Chinese porcelain beginning in the T’ang Dynasty. Copper(II) (Cu²⁺) also produces many blue compounds, including the commercial algicide copper(II) sulfate (CuSO₄^.5H₂O). Similarly, vanadyl salts and solutions are often blue, e.g. vanadyl sulfate.

In nature

Sky and sea

When sunlight passes through the atmosphere, the blue wavelengths are scattered more widely by the oxygen and nitrogen molecules, and more blue comes to our eyes. This effect is called Rayleigh scattering, after Lord Rayleigh and confirmed by Albert Einstein in 1911.^[23][24]

The sea is seen as blue for largely the same reason: the water absorbs the longer wavelengths of red and reflects and scatters the blue, which comes to the eye of the viewer. The deeper the observer goes, the darker the blue becomes. In the open sea, only about one per cent of light penetrates to a depth of 200 metres. (See underwater and euphotic depth)

The colour of the sea is also affected by the colour of the sky, reflected by particles in the water; and by algae and plant life in the water, which can make it look green; or by sediment, which can make it look brown.^[25]

The farther away an object is, the more blue it often appears to the eye. For example, mountains in the distance often appear blue. This is the effect of atmospheric perspective; the farther an object is away from the viewer, the less contrast there is between the object and its background colour, which is usually blue. In a painting where different parts of the composition are blue, green and red, the blue will appear to be more distant, and the red closer to the viewer. The cooler a colour is, the more distant it seems.^[26] Blue light is scattered more than other wavelengths by the gases in the atmosphere, hence our «blue planet».

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  Earth’s blue halo when seen from space.

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  The sea.

Minerals

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  Natural ultramarine pigment

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Some of the most desirable gems are blue, including sapphire and tanzanite. Compounds of copper(II) are characteristically blue and so are many copper-containing minerals.
Azurite (Cu₃(CO₃)₂(OH)₂), with a deep blue colour, was once employed in medieval years, but it is unstable pigment, losing its colour especially under dry conditions. Lapis lazuli, mined in Afghanistan for more than three thousand years, was used for jewelry and ornaments, and later was crushed and powdered and used as a pigment. The more it was ground, the lighter the blue colour became. Natural ultramarine, made by grinding lapis lazuli into a fine powder, was the finest available blue pigment in the Middle Ages and the Renaissance. It was extremely expensive, and in Italian Renaissance art, it was often reserved for the robes of the Virgin Mary.

Plants and fungi

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  Primula acaulis

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  Blue Delphinium flower

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Intense efforts have focused on blue flowers and the possibility that natural blue colourants could be used as food dyes.^[21] Commonly, blue colours in plants are anthocyanins: «the largest group of water-soluble pigments found widespread in the plant kingdom.»^[28] In the few plants that exploit structural colouration, brilliant colours are produced by structures within cells. The most brilliant blue colouration known in any living tissue is found in the marble berries of Pollia condensata, where a spiral structure of cellulose fibrils scattering blue light. The fruit of quandong (Santalum acuminatum) can appear blue owing to the same effect.^[21]

Animals

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Blue-pigmented animals are relatively rare.^[29] Examples of which include butterflies of the genus Nessaea, where blue is created by pterobilin.^[30] Other blue pigments of animal origin include phorcabilin, used by other butterflies in Graphium and Papilio (specifically P. phorcas and P. weiskei), and sarpedobilin, which is used by Graphium sarpedon.^[31] Blue-pigmented organelles, known as «cyanosomes», exist in the chromatophores of at least two fish species, the mandarin fish and the picturesque dragonet.^[32] More commonly, blueness in animals is a structural colouration; an optical interference effect induced by organized nanometer-sized scales or fibres. Examples include the plumage of several birds like the blue jay and indigo bunting,^[33] the scales of butterflies like the morpho butterfly,^[34] collagen fibres in the skin of some species of monkey and opossum,^[35] and the iridophore cells in some fish and frogs.^[36][37]

Eyes

Blue eyes do not actually contain any blue pigment. Eye colour is determined by two factors: the pigmentation of the eye’s iris^[38][39] and the scattering of light by the turbid medium in the stroma of the iris.^[40] In humans, the pigmentation of the iris varies from light brown to black. The appearance of blue, green, and hazel eyes results from the Tyndall scattering of light in the stroma, an optical effect similar to what accounts for the blueness of the sky.^[40][41] The irises of the eyes of people with blue eyes contain less dark melanin than those of people with brown eyes, which means that they absorb less short-wavelength blue light, which is instead reflected out to the viewer. Eye colour also varies depending on the lighting conditions, especially for lighter-coloured eyes.

Blue eyes are most common in Ireland, the Baltic Sea area and Northern Europe,^[42] and are also found in Eastern, Central, and Southern Europe. Blue eyes are also found in parts of Western Asia, most notably in Afghanistan, Syria, Iraq, and Iran.^[43] In Estonia, 99% of people have blue eyes.^[44][45] In Denmark in 1978, only 8% of the population had brown eyes, though through immigration, today that number is about 11%.^[45] In Germany, about 75% have blue eyes.^[45]

In the United States, as of 2006, one out of every six people, or 16.6% of the total population, and 22.3% of the white population, have blue eyes, compared with about half of Americans born in 1900, and a third of Americans born in 1950. Blue eyes are becoming less common among American children^{[citation needed]}. In the US, boys are 3–5 per cent more likely to have blue eyes than girls.^[42]

History

In the ancient world

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  Lapis lazuli bowl from Iran, end of 3rd – beginning of 2nd millennium BC (Louvre Museum)

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  Egyptian blue tripodic beaker imitating lapis lazuli. South Mesopotamia. (1399-1200 BC)

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  Fresco of Polyphemus and Galatea, Pompei, using Egyptian blue (1st c. BC) (Metropolitan Museum)

As early as the 7th millennium BC, lapis lazuli was mined in the Sar-i Sang mines,^[46] in Shortugai, and in other mines in Badakhshan province in northeast Afghanistan.^[47]

Lapis lazuli artifacts, dated to 7570 BC, have been found at Bhirrana, which is the oldest site of Indus Valley civilisation.^[48] Lapis was highly valued by the Indus Valley Civilisation (7570–1900 BC).^[48][49][50] Lapis beads have been found at Neolithic burials in Mehrgarh, the Caucasus, and as far away as Mauritania.^[51] It was used in the funeral mask of Tutankhamun (1341–1323 BC).^[52]

A term for Blue was relatively rare in many forms of ancient art and decoration, and even in ancient literature. The Ancient Greek poets described the sea as green, brown or «the colour of wine». The colour is mentioned several times in the Hebrew Bible as ‘tekhelet’. Reds, blacks, browns, and ochres are found in cave paintings from the Upper Paleolithic period, but not blue. Blue was also not used for dyeing fabric until long after red, ochre, pink, and purple. This is probably due to the perennial difficulty of making blue dyes and pigments. On the other hand, the rarity of blue pigment made it even more valuable.^[53]

The earliest known blue dyes were made from plants – woad in Europe, indigo in Asia and Africa, while blue pigments were made from minerals, usually either lapis lazuli or azurite, and required more.^[54] Blue glazes posed still another challenge since the early blue dyes and pigments were not thermally robust. In ca. 2500 BC, the blue glaze Egyptian blue was introduced for ceramics, as well as many other objects.^[55][56] The Greeks imported indigo dye from India, calling it indikon, and they painted with Egyptian blue. Blue was not one of the four primary colours for Greek painting described by Pliny the Elder (red, yellow, black, and white). For the Romans, blue was the colour of mourning, as well as the colour of barbarians. The Celts and Germans reportedly dyed their faces blue to frighten their enemies, and tinted their hair blue when they grew old.^[57] The Romans made extensive use of indigo and Egyptian blue pigment, as evidenced, in part, by frescos in Pompeii.
The Romans had many words for varieties of blue, including caeruleus, caesius, glaucus, cyaneus, lividus, venetus, aerius, and ferreus, but two words, both of foreign origin, became the most enduring; blavus, from the Germanic word blau, which eventually became bleu or blue; and azureus, from the Arabic word lazaward, which became azure.^[58]

Blue was widely used in the decoration of churches in the Byzantine Empire.^[59] By contrast, in the Islamic world, blue was of secondary to green, believed to be the favourite colour of the Prophet Mohammed. At certain times in Moorish Spain and other parts of the Islamic world, blue was the colour worn by Christians and Jews, because only Muslims were allowed to wear white and green.^[60]

In the Middle Ages

In the art and life of Europe during the early Middle Ages, blue played a minor role. This changed dramatically between 1130 and 1140 in Paris, when the Abbe Suger rebuilt the Saint Denis Basilica. Suger considered that light was the visible manifestation of the Holy Spirit.^[61] He installed stained glass windows coloured with cobalt, which, combined with the light from the red glass, filled the church with a bluish violet light. The church became the marvel of the Christian world, and the colour became known as the «bleu de Saint-Denis». In the years that followed even more elegant blue stained glass windows were installed in other churches, including at Chartres Cathedral and Sainte-Chapelle in Paris.^[62]

In the 12th century the Roman Catholic Church dictated that painters in Italy (and the rest of Europe consequently) to paint the Virgin Mary with blue, which became associated with holiness, humility and virtue. In medieval paintings, blue was used to attract the attention of the viewer to the Virgin Mary. Paintings of the mythical King Arthur began to show him dressed in blue. The coat of arms of the kings of France became an azure or light blue shield, sprinkled with golden fleur-de-lis or lilies. Blue had come from obscurity to become the royal colour.^[63]

Renaissance through 18th century

Blue came into wider use beginning in the Renaissance, when artists began to paint the world with perspective, depth, shadows, and light from a single source. In Renaissance paintings, artists tried to create harmonies between blue and red, lightening the blue with lead white paint and adding shadows and highlights. Raphael was a master of this technique, carefully balancing the reds and the blues so no one colour dominated the picture.^[64]

Ultramarine was the most prestigious blue of the Renaissance, being more expensive than gold. Wealthy art patrons commissioned works with the most expensive blues possible. In 1616 Richard Sackville commissioned a portrait of himself by Isaac Oliver with three different blues, including ultramarine pigment for his stockings.^[65]

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  Portrait of Richard Sackville (1616), using three expensive blues, including ultramarine for his stockings

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  Ming Dynasty, Porcelain vase painted with cobalt blue under transparent glaze. (15th c.) (Metropolitan Museum)

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  Delftware plaque with cobalt blue painting (1683) (Rijksmuseum, Amsterdam)

An industry for the manufacture of fine blue and white pottery began in the 14th century in Jingdezhen, China, using white Chinese porcelain decorated with patterns of cobalt blue, imported from Persia. It was first made for the family of the Emperor of China, then was exported around the world, with designs for export adapted to European subjects and tastes. The Chinese blue style was also adapted by Dutch craftsmen in Delft and English craftsmen in Staffordshire in the 17th-18th centuries. in the 18th century, blue and white porcelains were produced by Josiah Wedgwood and other British craftsmen.^[66]

19th-20th century

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  Beau Brummel (1776-1840) introduced the ancestor of the modern blue suit

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  A California gold miner in blue jeans (1853)

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  New York City police in 1871

The early 19th century saw the ancestor of the modern blue business suit, created by Beau Brummel (1776-1840), who set fashion at the London Court. It also saw the invention of blue jeans, a highly popular form of workers’s costume, invented in 1853 by Jacob W. Davis who used metal rivets to strengthen blue denim work clothing in the California gold fields. The invention was funded by San Francisco entrepreneur Levi Strauss, and spread around the world.^[67]

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  Van Gogh’s Starry Night Over the Rhône (1888). Blue used to create a mood or atmosphere. A cobalt blue sky, and cobalt or ultramarine water.

Recognizing the emotional power of blue, many artists made it the central element of paintings in the 19th and 20th centuries. They included Pablo Picasso, Pavel Kuznetsov and the Blue Rose art group, and Kandinsky and Der Blaue Reiter (The Blue Rider) school.^[68] Henri Matisse expressed deep emotions with blue:, «A certain blue penetrates your soul.»^[69] In the second half of the 20th century, painters of the abstract expressionist movement use blues to inspire ideas and emotions. Painter Mark Rothko observed that colour was «only an instrument;» his interest was «in expressing human emotions tragedy, ecstasy, doom, and so on.»^[70]

In society and culture

Uniforms

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  Ukrainian police officer in Donetsk

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In the 17th century. The Prince-Elector of Brandenburg, Frederick William I of Prussia, chose Prussian blue as the new colour of Prussian military uniforms, because it was made with Woad, a local crop, rather than Indigo, which was produced by the colonies of Brandenburg’s rival, England. It was worn by the German army until World War I, with the exception of the soldiers of Bavaria, who wore sky-blue.^[71]

In 1748, the Royal Navy adopted a dark shade of blue for the uniform of officers.^[67] It was first known as marine blue, now known as navy blue.^[72] The militia organized by George Washington selected blue and buff, the colours of the British Whig Party. Blue continued to be the colour of the field uniform of the US Army until 1902, and is still the colour of the dress uniform.^[73]

In the 19th century, police in the United Kingdom, including the Metropolitan Police and the City of London Police also adopted a navy blue uniform. Similar traditions were embraced in France and Austria.^[74] It was also adopted at about the same time for the uniforms of the officers of the New York City Police Department.^[67]

Religion

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  Blue domes of the Church dedicated to St. Spirou in Firostefani, Santorini island (Thira), Greece.

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  The flag of Israel uses a special variety of blue, called tekhelet

• Blue in Judaism: In the Torah,^[75] the Israelites were commanded to put fringes, tzitzit, on the corners of their garments, and to weave within these fringes a «twisted thread of blue (tekhelet)».^[76] In ancient days, this blue thread was made from a dye extracted from a Mediterranean snail called the hilazon. Maimonides claimed that this blue was the colour of «the clear noonday sky»; Rashi, the colour of the evening sky.^[77] According to several rabbinic sages, blue is the colour of God’s Glory.^[78] Staring at this colour aids in mediation, bringing us a glimpse of the «pavement of sapphire, like the very sky for purity», which is a likeness of the Throne of God.^[79] (The Hebrew word for glory.) Many items in the Mishkan, the portable sanctuary in the wilderness, such as the menorah, many of the vessels, and the Ark of the Covenant, were covered with blue cloth when transported from place to place.^[80]
• Blue in Christianity: Blue is particularly associated with the Virgin Mary. This was the result of a decree of Pope Gregory I (540-601) who ordered that all religious paintings should tell a story which was clearly comprehensible to all viewers, and that figures should be easily recognizable, especially that of the figure of Mary. If she was alone in the image, her costume was usually painted with the finest blue, ultramarine. If she was with Christ, her costume was usually painted with a less expensive pigment, to avoid outshining him.^{[81][82][83][84]}

• Blue in Hinduism: Many of the gods are depicted as having blue-coloured skin, particularly those associated with Vishnu, who is said to be the preserver of the world, and thus intimately connected to water. Krishna and Rama, Vishnu’s avatars, are usually depicted with blue skin. Shiva, the destroyer deity, is also depicted in a light-blue hue, and is called neela kantha, or blue-throated, for having swallowed poison to save the universe during the Samudra Manthana, the churning of the ocean of milk. Blue is used to symbolically represent the fifth, and the throat, chakra (Vishuddha).^[85]
• Blue in Sikhism: The Akali Nihangs warriors wear all-blue attire. Guru Gobind Singh also has a blue roan horse. The Sikh Rehat Maryada states that the Nishan Sahib hoisted outside every Gurudwara should be xanthic (Basanti in Punjabi) or greyish blue (modern day navy blue) (Surmaaee in Punjabi) colour.^[86][87]
• Blue in Paganism: Blue is associated with peace, truth, wisdom, protection, and patience. It helps with healing, psychic ability, harmony, and understanding.^[88]

Sports

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  Serbian national volleyball team, 2012 Olympics

In sports, blue is widely represented in uniforms in part because the majority of national teams wear the colours of their national flag. For example, the national men’s football team of France are known as Les Bleus (the Blues). Similarly, Argentina, Italy, and Uruguay wear blue shirts.^[89] The Asian Football Confederation and the Oceania Football Confederation use blue text on their logos. Blue is well represented in baseball (Blue Jays, basketball, and American football, and Ice hockey. The Indian national cricket team wears blue uniform during One day international matches, as such the team is also referred to as «Men in Blue».^[90]

Politics

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  A presidential-election map of the US, 2004–2016. States that consistently vote for Democrats are termed «blue states».

Unlike red or green, blue was not strongly associated with any particular country, religion or political movement. As the colour of harmony, it was chosen as the colour for the flags of the United Nations, the European Union, and NATO.^[91]

In politics, blue is sometimes used as the colour of conservative parties, contrasting with the red of more leftist parties.^[92] It is the colour of the British Conservative party. However, in the United States, the colours are reversed. To avoid associations of the Democrats with socialism or the far left, States which voted Democratic in four consecutive presidential elections are termed «blue states», while those which voted for Republicans are termed «red states».^[93] States which voted for different parties in two of the last four presidential elections are called «Swing States», and are usually coloured purple, a mix of red and blue, or sometimes pink or light blue.^[94]

See also

• Engineer’s blue
• Lists of colours
• Non-photo blue
• Blue pigments

References

Works cited

• Ball, Philip (2001). Bright Earth, Art, and the Invention of Colour. London: Penguin Group. p. 507. ISBN 978-2-7541-0503-3. (page numbers refer to the French translation)
• Bowersox, Gary W.; Chamberlin, Bonita E. (1995). Gemstones of Afghanistan. Tucson, AZ: Geoscience Press.
• Heller, Eva (2009). Psychologie de la couleur: effets et symboliques (in French). Munich: Pyramyd. ISBN 978-2-35017-156-2.
• Pastoureau, Michel (2000). Bleu: Histoire d’une couleur (in French). Paris: Editions du Seuil. ISBN 978-2-02-086991-1.
• Riley, Charles A., II (1995). Color Codes: Modern Theories of Color in Philosophy, Painting and Architecture, Literature, Music, and Psychology. Hanover, New Hampshire: University Press of New England.
• Travis, Tim (2020). The Victoria and Albert Museum Book of Colour in Design. Thames & Hudson. ISBN 978-0-500-48027-4.
• Varichon, Anne (2005). Couleurs : pigments et teintures dans les mains des peuples (in French). Paris: Editions du Seuil. ISBN 978-2-02-084697-4.
• Lours, Mathieu (2020). Le Vitrai. Éditions Jean-Paul Gisserot. ISBN 978-2-755-80845-2.

Further reading

• Balfour-Paul, Jenny (1998). Indigo. London: British Museum Press. ISBN 978-0-7141-1776-8.
• Josserand, M.; Meeussen, E.; Majid, A. (27 September 2021). «Environment and culture shape both the colour lexicon and the genetics of colour perception». Sci Rep. Nature. 11 (19095): 19095. Bibcode:2021NatSR..1119095J. doi:10.1038/s41598-021-98550-3. PMC 8476573. PMID 34580373. S2CID 238202924. Retrieved 24 June 2022.
• Macdonald, Fiona (7 April 2018). «There’s Evidence Humans Didn’t Actually See Blue Until Modern Times». Science Alert. Retrieved 24 June 2022.
• Mollo, John (1991). Uniforms of The American Revolution in Color. Illustrated by Malcolm McGregor. New York: Stirling Publications. ISBN 978-0-8069-8240-3.

External links

Blue
— Spectral coordinates —
Wavelength	440–490 nm
Frequency	~680–610 THz
— Common connotations —
ice, water, sky, sadness, winter, police, royalty, boys, cold, calm, magic, trueness, conservatism (universally), liberalism (US), and capitalism
— Colour coordinates —
Hex triplet	#0000FF
sRGBB	(r, g, b)	(0, 0, 255)
HSV	(h, s, v)	(240°, 100%, 100%)
Source	HTML/CSS[1]
B: Normalized to [0–255] (byte)

Blue is a colour, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440–490 nm. It is considered one of the additive primary colours. On the HSV Colour Wheel, the complement of blue is yellow; that is, a colour corresponding to an equal mixture of red and green light. On a colour wheel based on traditional colour theory (RYB) where blue was considered a primary colour, its complementary colour is considered to be orange (based on the Munsell colour wheel).^[2]

In Modern English, «blue» is one of the basic colour terms, and one of the seven spectral colours, intermediate between violet (purple) and cyan. It comprises a considerable number of identifiable subcategories that can be identified with descriptive terms like navy blue (a dark blue), cyan blue (or «blue-green», on the boundary to the green range), or sky blue (azure).

The word itself was loaned into Middle English from the Old French word bleu, blo » «pale, pallid, discoloured; blue, blue-grey», itself from an Old Frankish *blao.

Etymology and definitions

The modern English word blue comes from Middle English bleu or blewe, from Old French bleu, bleve, blöe, a word of Germanic origin (Frankish or possibly Old High German blāo, «pale, wan, blue-grey»).

Bleu replaced Old English blāw «blue» and blǣwen «light blue». The root of all these variations is Proto-Germanic blǣwaz, from Proto-Indo-European *bhlāw-, *bhlēw- «light-coloured, yellow, grey, blue», from *bhel- «to shine, be light or bright», also the root of Old Norse blār and the modern Icelandic blár, and the Scandinavian word blå, which can also refer to other non blue colours. Also in the French, bleau is a contraction of belleaue or belle eau, meaning «beautiful water» (see Fontainebleau). In this vein, «blue» is the colour of beautiful water as it clearly reflects the blue sky. A Scots and Scottish English word for «blue-grey» is blae, from the Middle English bla («dark blue», from Old Norse blār). Also related is the English word blee meaning «colour, complexion». Ancient Greek lacked a word for blue and Homer called the colour of the sea «wine dark», except that the word kyanos (cyan) was used for dark blue enamel.

The word blue is thought to be cognate with black, blond, originally designating a discoloured, pale, washed-out shade. Through a Proto-Indo-European root, it is also linked with Latin flavus («yellow»; see flavescent and flavine), with Greek phalos (white), French blanc (white, blank) (borrowed from Old Frankish), and with Russian белый, belyi («white,» see beluga), and Welsh blawr (grey) all of which derive (according to the American Heritage Dictionary) from the Proto-Indo-European root *bhel- meaning «to shine, flash or burn», (more specifically the word bhle-was, which meant light coloured, blue, blond, or yellow), whence came the names of various bright colours, and that of colour black from a derivation meaning «burnt» (other words derived from the root *bhel- include bleach, bleak, blind, blink, blank, blush, blaze, flame, fulminate, flagrant and phlegm).

In the English language, blue may refer to the feeling of sadness. «He was feeling blue». This is because blue was related to rain, or storms, and in Greek mythology, the god Zeus would make rain when he was sad (crying), and a storm when he was angry. Kyanos was a name used in Ancient Greek to refer to dark blue tile (in English it means blue-green or cyan).^[3]

Many languages do not have separate terms for blue and or green, instead using a cover term for both (when the issue is discussed in linguistics, this cover term is sometimes called grue in English).

In science

Pigments and dyes

Traditionally, blue has been considered a primary colour in painting, with the secondary colour orange as its complement.

Blue pigments include azurite (Cu₃(CO₃)₂(OH)₂), ultramarine (Na_8-10Al₆Si₆O₂₄S_2-4), cerulean blue (primarily cobalt (II) stanate: Co₂SnO₄), cobalt blue (cobalt(II) aluminate: CoAl₂O₄), and Prussian blue (milori blue: primarily Fe₇(CN)₁₈).

Traditionally natural dyes such as woad and true indigo were used to produce indigo dye used to colour fabrics blue or indigo. These have now largely been replaced by synthetic dyes.

Scientific natural standards for blue

• Emission spectrum of Cu²⁺
• Electronic spectrum of aqua-ions Cu(H₂O)2+
  6

Animals

• When an animal’s coat is described as «blue», it usually refers to a shade of grey that takes on a bluish tint, a diluted variant of a pure black coat.^{[citation needed]} This designation is used for a variety of animals, including dog coats, some rat coats, cat coats, some chicken breeds, some horse coat colours and rabbit coat colours. Some animals, such as giraffes and lizards, also have blue tongues.

Lasers

Lasers emitting in the blue region of the spectrum became widely available to the public in 2010 with the release of inexpensive high-powered 445-447nm Laser diode technology. ^[4] Previously the blue wavelengths were accessible only through DPSS which are comparatively expensive and inefficient, however these technologies are still widely used by the scientific community for applications including Optogenetics, Raman spectroscopy, and Particle image velocimetry, due to their superior beam quality. ^[5] Blue Gas lasers are also still commonly used for Holography, DNA sequencing, Optical pumping, and other scientific and medical applications.

In culture

Symbolic language

• In the English language, blue often represents the human emotion of sadness, for example, «He was feeling blue». In German, on the other hand, to be «blue» (blau sein) is to be drunk. This derives from the ancient use of urine (which is produced copiously by the human body after drinking alcohol) in dyeing cloth blue with woad or indigo.^[6] It may also be in relation to rain, which is usually regarded as a trigger of depressive emotions.^[7]

• Conversely blue, a very popular colour^[8] can represent happiness and optimism^[9] as days with clearer, blue skies tend to be considered times where these emotions are more easily expressed. Many artistic contributions have been made referencing clear days with blue skies as part of the happiness or as a symbolism of the happiness the artist felt, such as Tony Bennett’s Put on a Happy Face.^[10] If this were untrue there would obviously be more complaints about days with clear blue skies.

• Blue is commonly used in the Western hemisphere to symbolize the male gender in contrast to pink used for females, although in the early 1900s, blue was the colour for girls (as it had traditionally been the colour of the Virgin Mary in Western Art) and pink was for boys (as it was akin to the colour red, considered a masculine colour.^[11]

National colours

• Azzurro, a light blue, is the national colour of Italy (from the livery colour of the former reigning family, the House of Savoy).
• Blue is the national sports colour for India, as it denotes secularism.^{[citation needed]}
• Blue is the national colour used on flags of several countries surrounded by seas or oceans such as Australia and Europe, though not necessarily with this interpretation in mind.
• Blue and white are the national colours of Scotland, Argentina, El Salvador, Finland, Greece, Guatemala, Honduras, Israel, Micronesia, Nicaragua and Somalia, are the ancient national colours of Portugal and are the colours of the United Nations.
• Blue, white and yellow are the national colours of Bosnia and Herzegovina, Kosovo and Uruguay.
• Blue, white and black are the national colours of Estonia.^[12]
• Blue and yellow are the national colours of Barbados, Kazakhstan, Palau, Sweden, and Ukraine.
• Blue, yellow and green are the national colours of Brazil, Gabon, and Rwanda.
• Blue, yellow and red are the national colours of Chad, Colombia, Ecuador, Moldova, Romania, and Venezuela.
• Blue and red are the national colours of Haiti and Liechtenstein.
• Blue, red and white are the national colours of Cambodia, Costa Rica, Chile, Croatia, Cuba, the Czech Republic, the Dominican Republic, France, Iceland, North Korea, Laos, Liberia, Luxembourg, Nepal, the Netherlands, New Zealand, Norway, Panama, Paraguay, Puerto Rico, Russia, Samoa, Serbia, Slovakia, Slovenia, Thailand, the United Kingdom, and the United States.

Mysticism

• In Hinduism, blue is used to symbolically represent the fifth, throat chakra (Vishuddha).^[13]

Politics

• The Blue House is the residence of the President of South Korea.^[14]
• Blue has been associated with a variety of political positions, often differentiated from communist red or anarchist black. During the revolt in the Vendée against the French Revolution, blues stood for the revolutionary forces, and white for the counter-revolutionaries. Later movements like the Breton blues used the colour to signify allegiance to the ideals of the revolution.
• The blueshirts was a quasi-fascist political organisation active in Ireland during the 1930s (the name comes from the fact that St. Patrick’s Blue is one of the traditional colours of Ireland).
• Blue is the colour of the Conservative Party in Britain and Conservative Party of Canada. Television coverage in the United States since the 2000 presidential election has made it fashionable to link the Democratic Party to «blue» and the Republican Party to «red» (especially in reference to «red states and blue states»).^[15] In Brazil, blue states are the ones in which the Social Democratic Party has the majority, in opposition to the Workers’ Party, usually represented by red.

• A blue law is a type of law, typically found in the United States and Canada, designed to enforce religious standards, particularly the observance of Sunday as a day of worship or rest, and a restriction on Sunday shopping. The word blue was used in the 17th century as a disparaging reference to rigid moral codes and those who observed them, particularly in blue-stocking, a reference to Oliver Cromwell’s supporters in the parliament of 1653.
• Blue is associated with numerous centre-right liberal political parties in Europe, Including the People’s Party for Freedom and Democracy (Netherlands), the Reformist Movement and Open VLD (Belgium), the Democratic Party (Luxembourg), Liberal Party (Denmark) and Liberal People’s Party (Sweden).

• Blue is the colour of, and associated with, the New Progressive Party of Puerto Rico.

Religion

• Blue is associated in Christianity generally and Catholicism in particular, with the Virgin Mary.^[16][17][18]
• Blue in Hinduism: Many of the gods are depicted as having blue-coloured skin, particularly those associated with Vishnu, who is said to be the Preserver of the world and thus intimately connected to water. Krishna and Ram, Vishnu’s avatars, are usually blue. Shiva, the Destroyer, is also depicted in light blue tones and is called neela kantha, or blue-throated, for having swallowed poison in an attempt to turn the tide of a battle between the gods and demons in the gods’ favour.
• Blue in Judaism: In the Torah,^[19] the Israelites were commanded to put fringes, tzitzit, on the corners of their garments, and to weave within these fringes a «twisted thread of blue (tekhelet)».^[20] In ancient days, this blue thread was made from a dye extracted from a Mediterranean snail called the hilazon. Maimonides claimed that this blue was the colour of «the clear noonday sky»; Rashi, the colour of the evening sky.^[21] According to several rabbinic sages, blue is the colour of God’s Glory.^[22] Staring at this colour aids in mediation, bringing us a glimpse of the «pavement of sapphire, like the very sky for purity», which is a likeness of the Throne of God.^[23] (The Hebrew word for glory.) Many items in the Mishkan, the portable sanctuary in the wilderness, such as the menorah, many of the vessels, and the Ark of the Covenant, were covered with blue cloth when transported from place to place.^[24]
• Blue in Islam: the colour blue is mentioned in the Quran: In verse 20:102 and is represented by the word: زرق zurq (plural of azraq, ‘blue’). Blue amulets made of Lapis lazuli are commonly utilised to symbolise luck in some Muslim cultures. The colour blue also represents the values of liberty among Bosniaks.

Symbolism

• In Thailand, blue is associated with Friday on the Thai solar calendar. Anyone may wear blue on Fridays and anyone born on a Friday may adopt blue as their colour. The Thai language, however, is one that has had trouble distinguishing blue from green. The default word for Blue was recently สีน้ำเงิน literally, the colour of silver, a poetical reference to the silvery sheen of the deep blue sea. It now means navy blue, and the default word is now สีฟ้า literally, the colour of the sky.^[25]

Business

Blue is associated with many large companies and brands, including:

• American Airlines
• American Express
• AOL
• Atlas Air
• British Airways
• Carrefour
• Delta Air Lines
• El Vocero
• Facebook
• Fed Ex
• Foster’s Lager
• Gerber Foods
• Goodwill Industries
• International Business Machines (IBM) («Big Blue»)
• JetBlue
• KLM Royal Dutch Airlines
• Kone
• Long John Silvers
• Old Navy
• PepsiCo
• Polar Air Cargo
• Tiendas Kress
• Tesco
• Twitter
• Wonder Bread
• Wal-Mart

Sports

Many sporting teams make blue their official colour, or use it as detail on kit of a different colour. In addition, the colour is present on the logos of many sports associations.

Association football

In international association football, blue is a common colour on kits, as a majority of nations wear the colours of their national flag. A notbale exception is four-time FIFA World Cup winners Italy, who wear a blue kit based on the Azzuro Savoia (Savoy blue) of the royal House of Savoy which unified the Italian states. ^[26] The team themsleves are known as I Azzuri (the Blues). Another World Cup winning nation with a blue shirt is France, who are known as Les Bleus (the Blues). Two neighbouring countries with two World Cup victories each, Argentina and Uruguay wear a light blue shirt, the former with white stripes. Uruguay are known as the La Celeste, Spanish for ‘the sky blue one’, while Argentina are known as Los Albicelestes, Spanish for ‘the sky blue and whites’. ^[27]

Football clubs which have won the European Cup or Champions League and wear blue include FC Barcelona of Spain (red and blue stripes), FC Internazionale Milano of Italy (blue and black stripes) and FC Porto of Portugal (blue and white stripes). Another European Cup-winning club, Aston Villa of England, wear light blue detailing on a mostly claret shirt, often as the colour of the sleeves ^[28]. Clubs which have won the Copa Libertadores, a tournament for South American clubs, and wear blue include six-times winners Boca Juniors of Buenos Aires, Argentina. They wear a blue shirt with a yellow band across.

Blue features on the logo of football’s governing body FIFA, as well as featuring highly in the design of their website ^[29]. The European governing body of football, UEFA, uses two tones of blue to create a map of Europe in the centre of their logo. The Asian Football Confederation, Oceania Football Confederation and CONCACAF (the governing body of football in North and Central America and the Caribbean) use blue text on their logos.

North American sporting leagues

In Major League Baseball, a premier baseball league in the United States of America and Canada, blue is one of the three colours, along with white and red, on the league’s official logo. A team from Toronto, Ontario, are the Blue Jays. The Los Angeles Dodgers use blue prominently on their uniforms and the phrase «Dodger Blue» is may be said to describe Dodger fans’ «blood». The Texas Rangers also use Blue prominently on their uniforms and logo.

The National Basketball Association, a premier basketball league in the United States and Canada, also has blue as one of the colours on their logo, along with red and white also, as does its female equivalent, the WNBA. The Sacramento Monarchs of the WNBA wear blue. Former NBA player Theodore Edwards was nicknamed «Blue». The only NBA team to wear blue as first choice are the Charlotte Bobcats, however blue is a common away colour for many other franchises.

The National Football League, an American Football league in the United States, also uses blue as one of three colours, along with white and red, on their official logo. The Seattle Seahawks, New York Giants, Buffalo Bills and Detroit Lions feature blue prominently on their uniforms.

The National Hockey League, a premier Ice hockey league in Canada and the United States, does not use blue on its official logo. However, a club in the league from St. Louis, Missouri is named the Blues.

Variations

Main article: Variations of blue

See also

• Blue Flag (disambiguation)
• Blue movie (disambiguation)
• Blue ribbon
• Blue Screen of Death
• Distinguishing «blue» from «green» in language
• Engineer’s blue
• Lapis lazuli, a blue stone
• List of colours
• Non-photo blue
• St. Patrick’s Blue
• Turquoise
• Variations of blue

References

v · d · e Web colours
black	gray	silver	white	maroon	red	purple	fuchsia	green	lime	olive	yellow	navy	blue	teal	aqua

v · d · e Shades of blue
Air Force blue	Alice blue	Azure	Baby blue	Bleu de France	Blue	Bondi blue	Brandeis blue	Cambridge Blue	Carolina blue
Celeste	Cerulean	Cobalt blue	Columbia blue	Cornflower blue	Cyan	Dark blue	Deep sky blue	Dodger blue	Duke blue
Egyptian blue	Electric blue	Eton blue	Federal blue	Glaucous	Electric indigo	International Klein Blue	Iris	Light blue	Majorelle Blue
Maya blue	Midnight blue	Navy blue	Non-photo blue	Palatinate blue	Periwinkle	Persian blue	Phthalo blue	Powder blue	Prussian blue
Royal blue	Sapphire	Sky blue	Steel blue	Teal	Tiffany Blue	True Blue	Tufts Blue	Turquoise	UCLA Blue
Ultramarine	Yale Blue
The samples shown above are only indicative.

Azure Mist (web color: Azure) (Hex: #F0FFFF) (RGB: 240, 255, 255) Alice Blue (web color) (Hex: #F0F8FF) (RGB: 240, 248, 255) Bubbles (Xona.com Color List) (Hex: #E7FEFF) (RGB: 231, 254, 255) Light Cyan (Hex: #E0FFFF) (RGB: 244, 255, 255) Powder Blue (Hex: #9EB9D4) (RGB: 158, 185, 212) Lavender Mist (web color: Lavender) (Hex: #E6E6FA) (RGB: 230, 230, 250) Periwinkle (Lavender Blue) (Pastel Indigo) (Hex: #CCCCFF) (RGB: 204, 204, 255) Pale Blue (web color) (Hex: #B0E0E6) (RGB: 176, 224, 230) Light Blue (Hex: #ADD8E6) (RGB: 173, 216, 230) Ultra Blue (Crayola: Blizzard Blue) (Hex: #ACE5EE) (RGB: 172, 229, 238) Baby Blue (Hex: 89CFF0) (RGB: 137, 207, 240) Light Sky Blue (web color) (Hex: #87CEFA) (RGB: 135, 196, 250) Sky Blue (web color) (Hex: #87CEEB) (RGB: 135, 206, 235) Light Cornflower Blue (Crayola: Cornflower) (Hex: #93CCEA) (RGB: 147, 204, 234) Medium Sky Blue (Crayola: Sky Blue) (Hex: #76D7EA) (RGB: 118, 215, 234) Aquamarine Blue (Crayola: Aquamarine) (Hex: #71D9E2) (RGB: 113, 217, 226) Aquamarine (web color) (Hex: #7FFFD4) (RGB: 127, 255, 212) Electric Blue (Hex: #7DF9FF) (RGB: 125, 249, 255) Cyan (web color Aqua) (Electric Cyan) (Hex: #00FFFF) (RGB: 0, 255, 255) Turquoise Blue (Hex: #00FFEF) (RGB: 0, 255, 239) Bright Turquoise (Hex: #08E8DE) (RGB: 8, 232, 222) Turquoise (web color) (Hex: #40E0D0) (RGB: 64, 224, 208) Capri (web color: Deep Sky Blue) (Hex: #00BFFF) (RGB: 0, 191, 255) Process Cyan (Pigment Cyan) (Printer’s Cyan)(Deep Aqua) (Hex: #00B7EB) (RGB: 0, 180, 247) Ukrainian Azure (color of Ukrainian Flag) (Hex: #42ADDE) (RGB: 66, 173, 222) United Nations Blue (United Nations Azure) (Hex: #5B92E5) (RGB: 91, 146, 229) Cornflower Blue (web color) (Hex: #6495ED) (RGB: 100, 149, 237) Bright Cerulean (Crayola: Cerulean) (Hex: #02A4D3) (RGB: 2, 164, 211) Bondi Blue (Crayola: Blue-Green) (Hex: #0095B6) (RGB: 0, 149, 182) Rich Electric Blue (Hex: #0892D0) (RGB: 8, 146, 208) Cerulean (Hex: #007BA7) (RGB: 0, 123, 167) Teal (web color) (Hex: #008080) (RGB: 0, 128, 128) Teal Blue (Hex: #367588) (RGB: 54, 117, 136) Steel Blue (web color) (Hex: #4682B4) (RGB: 70, 130, 180) Air Force Blue (Hex: #5D8AA8) (RGB: 93, 138, 168) Blue-gray (Hex: #506D8A) (RGB: 80, 109, 138) Agate Blue (Hex: #44719B) (RGB: 68, 113, 155) Medium Persian Blue (Hex: #0067A5) (RGB: 0, 103, 165) Swedish Azure (color of Swedish flag) (Hex: #005B99) (RGB: 0, 91, 153) Indigo Dye (Hex: #1A5798) (RGB: 17, 80, 147) Bright Indigo (Crayola: Indigo) (Hex: #4F69C6) (RGB: 79, 105, 198) Royal Blue (web color) (Hex: #4169E1) (RGB: 65, 105, 225) Dodger Blue (web color) (Hex: #1E90FF) (RGB: 30, 144, 255) Azure (Hex: #007FFF) (RGB: 0, 127, 255) Deep Azure (Crayola: Blue) (Hex: #0066FF) (RGB: 0, 102, 255) Blue (Hex: #0000FF) (RGB: 0, 0, 255) Cerulean Blue (Hex: #2A52BE) (RGB: 42, 82, 190) Denim (Hex: #1560bd) (RGB: 21, 96, 189) Medium Navy Blue (Crayola: Navy Blue) (Hex: #0066CC) (RGB: 0, 102, 204) Sapphire (Maerz and Paul) (Hex: #0F52BA) (RGB: 15, 82, 186) Medium Electric Blue (Hex: #035096) (RGB: 3, 80, 150) Cobalt Blue (Hex: #0047AB) (RGB: 0, 71, 171) Persian Blue (Hex: #1C39BB) (RGB: 28, 57, 187) Azul (Hex: #002BB8) (RGB: 0, 43, 184) Medium Blue (web color) (Hex: #0000CD) (RGB: 0, 0, 205) Han Blue (Hex: #446CCF) (RGB: 68, 108, 207) Electric Ultramarine (Hex: #3F00FF) (RGB: 63, 0, 255) Westminster (Hex: #5F00FF) (RGB: 95, 0, 255) Indigo (Electric Indigo) (Hex: #6600FF) (RGB: 102, 0, 255) Medium Slate Blue (web color) (Hex: #7B68EE) (RGB: 123, 104, 238) Deep Lavender (web color Medium Purple) (Hex: #9370DB) (RGB: 147, 112, 219) Lavender (Hex: #B57EDC) (RGB: 181, 126, 220) Lavender Indigo (Hex: #9457EB) (RGB: 148, 87, 235) Deep Indigo (web color: Blue-Violet) (Hex: #8A2BE2) (RGB: 138, 43, 226) Pigment Indigo (web color: Indigo) (Hex: #4B0082) (RGB: 75, 0, 130) Persian Indigo (Regimental) (Hex: #32127A) (RGB: 50, 18, 122) Dark Azure (Pantone Blue #286) (Hex: #0038A8) (RGB: 0, 56, 168) International Klein Blue (Hex: #002FA7) (RGB: 0, 47, 167) Dark Powder Blue (Smalt) (Hex: #003399) (RGB: 0, 51, 153) Ultramarine (Hex: #120A8F) (RGB: 18, 10, 143) Dark Blue (web color) (Hex: #00008B) (RGB: 0, 0, 139) Navy blue (web color Navy) (Hex: #000080) (RGB: 0, 0, 128) St. Patrick’s Blue (Hex: #23297A) (RGB: 35, 41, 122) Dark Sapphire (Sapphire (PerBang.dk)) (Hex: #082567) (RGB: 8, 37, 103) Midnight Blue (web color) (Hex: #191970) (RGB: 25, 25, 112) Dark Midnight Blue (Crayola: Midnight Blue) (Hex: #003366) (RGB: 0, 51, 102) Prussian Blue (Berlin Blue) (Hex: #003153) (RGB: 0, 49, 83) Dark Indigo (Hex: #310062) (RGB: 49, 0, 98) Dark Electric Blue (Hex: #536878) (RGB: 83, 104, 120)

The color blue is associated with two of Earth’s greatest natural features: the sky and the ocean. But that wasn’t always the case. Some scientists believe that the earliest humans were actually colorblind and could only recognize black, white, red, and only later yellow and green. As a result, early humans with no concept of the color blue simply had no words to describe it. This is even reflected in ancient literature, such as Homer’s Odyssey, that describes the ocean as a “wine-red sea.”

Blue was first produced by the ancient Egyptians who figured out how to create a permanent pigment that they used for decorative arts. The color blue continued to evolve for the next 6,000 years, and certain pigments were even used by the world’s master artists to create some of the most famous works of art. Today it continues to evolve, with the latest shade discovered less than a decade ago. Read on to learn more about the color’s fascinating history.

First photo: Krzysztof Kowalski

Egyptian Blue

Egyptian Juglet, ca. 1750–1640 B.C. (Photo: Met Museum, Rogers Fund and Edward S. Harkness Gift, 1922. (CC0 1.0))

There’s a long list of things we can thank the ancient Egyptians for inventing, and one of them is the color blue. Considered to be the first ever synthetically produced color pigment, Egyptian blue (also known as cuprorivaite) was created around 2,200 B.C. It was made from ground limestone mixed with sand and a copper-containing mineral, such as azurite or malachite, which was then heated between 1470 and 1650°F. The result was an opaque blue glass which then had to be crushed and combined with thickening agents such as egg whites to create a long-lasting paint or glaze.

The Egyptians held the hue in very high regard and used it to paint ceramics, statues, and even to decorate the tombs of the pharaohs. The color remained popular throughout the Roman Empire and was used until the end of the Greco-Roman period (332 BC–395 AD), when new methods of color production started to evolve.

Figure of a Lion. ca. 1981–1640 B.C. (Photo: Met Museum, Rogers Fund and Edward S. Harkness Gift, 1922. (CC0 1.0))

Fun fact: In 2006, scientists discovered that Egyptian blue glows under fluorescent lights, indicating that the pigment emits infrared radiation. This discovery has made it a lot easier for historians to identify the color on ancient artifacts, even when it’s not visible to the naked eye.

Ultramarine

“Virgin and Child with Female Saints” by Gérard David, 1500. (Photo: Wikimedia Commons)

The history of ultramarine began around 6,000 years ago when the vibrant, semi-precious gemstone it was made from—lapis lazuli—began to be imported by the Egyptians from the mountains of Afghanistan. However, the Egyptians tried and failed to turn it into a paint, with each attempt resulting in a dull gray. Instead, they used it to make jewelry and headdresses.

Also known as “true blue,” lapis lazuli first appeared as a pigment in the 6th century and was used in Buddhist paintings in Bamiyan, Afghanistan. It was renamed ultramarine—in Latin: ultramarinus, meaning “beyond the sea”—when the pigment was imported into Europe by Italian traders during the 14th and 15th centuries. Its deep, royal blue quality meant that was highly sought after among artists living in Medieval Europe. However, in order to use it you had to be wealthy, as it was considered to be just as precious as gold.

“Girl with a Pearl Earring” by Johannes Vermeer, circa 1665. (Photo: Wikimedia Commons {{PD-US}})

Ultramarine was usually reserved for only the most important commissions, such as the blue robes of the Virgin Mary in Gérard David’s Virgin and Child with Female Saints. Supposedly, Baroque master Johannes Vermeer—who painted Girl with a Pearl Earring—loved the color so much that he pushed his family into debt. It remained extremely expensive until a synthetic ultramarine was invented in 1826, by a French chemist, which was then aptly named “French Ultramarine.”

Fun fact: Art historians believe that Michelangelo left his painting The Entombment (1500–01) unfinished because he could not afford to buy more ultramarine blue.

Cobalt blue

“The Skiff (La Yole)” by Pierre-Auguste Renoir, 1875. (Photo: Wikimedia Commons {{PD-US}})

Cobalt blue dates back to the 8th and 9th centuries, and was then used to color ceramics and jewelry. This was especially the case in China, where it was used in distinctive blue and white patterned porcelain. A purer alumina-based version was later discovered by French chemist Louis Jacques Thénard in 1802, and commercial production began in France in 1807. Painters—such as J. M. W. Turner, Pierre-Auguste Renoir, and Vincent Van Gogh—started using the new pigment as an alternative to expensive ultramarine.

Fun fact: Cobalt blue is sometimes called Parrish blue because artist Maxfield Parrish used it to create his distinct, intensely blue skyscapes.

Cerulean

Originally composed of cobalt magnesium stannate, the sky-colored cerulean blue was perfected by Andreas Höpfner in Germany in 1805 by roasting cobalt and tin oxides. However, the color was not available as an artistic pigment until 1860 when it was sold by Rowney and Company under the name of coeruleum. Artist Berthe Morisot used cerulean along with ultramarine and cobalt blue to paint the blue coat of the woman in A Summer’s Day, 1887.

Fun fact: In 1999, Pantone released a press release declaring cerulean as the “Color of the Millennium,” and “the hue of the future.”

Indigo

Indigo, historical dye collection of the Technical University of Dresden, Germany. (Photo: Wikimedia Commons (CC BY-SA 3.0))

Although blue was expensive to use in paintings, it was much cheaper to use for dying textiles. Unlike the rarity of lapis lazuli, the arrival of a new blue dye called “indigo” came from a excessively grown crop—called Indigofera tinctoria—that was produced across the world. Its import shook up the European textile trade in the 16th century, and catalyzed trade wars between Europe and America.

Indigo dyed textile (England), 1790s. (Photo: Matt Flynn via Wikimedia Commons {{PD-US}})

The use of indigo for dyeing textiles was most popular in England, and was used to dye clothing worn by men and women of all social backgrounds. Natural indigo was replaced in 1880, when synthetic indigo was developed. This pigment is still used today to dye blue jeans. However, over the last decade scientists have discovered that the bacteria Escherichia coli can be bio-engineered to produce the same chemical reaction that makes indigo in plants. This method, called “bio-indigo,” will likely play a big part in manufacturing environmentally friendly denim in the future.

Fun fact: Sir Isaac Newton—the inventor of the “color spectrum”—believed that the rainbow should consist of seven distinct colors to match the seven days of the week, the seven known planets, and the seven notes in the musical scale. Newton championed indigo, along with orange, even though many other contemporary scientists believed the rainbow only had five colors.

Navy blue

Formally known as marine blue, the darkest shade of blue—also known as navy blue—was adopted as the official color for British Royal Navy uniforms, and was worn by officers and sailors from 1748. Modern navies have since darkened the color of their uniforms to almost black in an attempt to avoid fading. Indigo dye was the basis for historical navy blue colors dating from the 18th century.

Fun fact: There are many variations of navy blue, including Space cadet, a color that was formulated in 2007. This hue is associated with the uniforms of cadets in the space navy; a fictional military service armed with the task of exploring outer space.

Prussian blue

“The Great Wave off Kanagawa” by Katsushika Hokusai, 1831. (Photo: Wikimedia Commons {{PD-US}})

Also known as Berliner Blau, Prussian blue was discovered accidentally by German dye-maker Johann Jacob Diesbach. In fact, Diesbach was working on creating a new red, however, one of his materials—potash—had come into contact with animal blood. Instead of making the pigment even more red like you might expect, the animal blood created a surprising chemical reaction, resulting in a vibrant blue.

Pablo Picasso used the Prussian blue pigment exclusively during his Blue Period, and Japanese woodblock artist Katsushika Hokusai used it to create his iconic The Great Wave off Kanagawa, as well as other prints in his Thirty-six Views of Mount Fuji series. However, the pigment wasn’t only used for creating masterpieces. In 1842, English astronomer Sir John Herschel discovered that Prussian blue had a unique sensitivity to light, and was the perfect hue to create copies of drawings. This discovery proved invaluable to the likes of architects, who could create copies of their plans and designs, that are today known as “blueprints.”

Fun fact: Today, Prussian blue is used in a pill form to cure metal poisoning.

International Klein Blue

“L’accord bleu (RE 10)”, 1960 by Yves Klein. (Photo: Wikimedia Commons (CC BY-SA 3.0))

“IKB 191”, 1962 by Yves Klein. (Photo: Christophe Brocas via Flickr (CC BY-NC-ND 2.0))

In pursuit of the color of the sky, French artist Yves Klein developed a matte version of ultramarine that he considered the best blue of all. He registered International Klein Blue (IKB) as a trademark and the deep hue became his signature between 1947 and 1957. He painted over 200 monochrome canvases, sculptures, and even painted human models in the IKB color so they could “print” their bodies onto canvas.

Fun fact: Klein once said “blue has no dimensions. It is beyond dimensions,” believing that it could take the viewer outside the canvas itself.

The Latest Discovery: YInMn

In 2009, a new shade of blue was accidentally discovered by Professor Mas Subramanian and his then graduate student Andrew E. Smith at Oregon State University. While exploring new materials for making electronics, Smith discovered that one of his samples turned bright blue when heated. Named YInMn blue, after its chemical makeup of yttrium, indium, and manganese, they released the pigment for commercial use in June 2016.

Fun fact: YInMn blue was recently added to the Crayola crayon collection.

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