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. It lies between violet and

cyan Cyan () is the color between blue and green on the visible spectrum of light. It is evoked by light with a predominant wavelength between 500 and 520 nm, between the wavelengths of green and blue. In the subtractive color system, or CMYK c ...

on the

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

of visible light. The term ''blue'' generally describes colours perceived by humans observing light with a dominant wavelength that's 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 the 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 The Renaissance ( , ) is a Periodization, period of history and a European cultural movement covering the 15th and 16th centuries. It marked the transition from the Middle Ages to modernity and was characterized by an effort to revive and sur ...

, 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 In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of global history. It began with the fall of the Western Roman Empire and ...

, European artists used it in the windows of

cathedral A cathedral is a church (building), church that contains the of a bishop, thus serving as the central church of a diocese, Annual conferences within Methodism, conference, or episcopate. Churches with the function of "cathedral" are usually s ...

s. Europeans wore clothing coloured with the vegetable dye

woad ''Isatis tinctoria'', also called woad (), dyer's woad, dyer's-weed, or glastum, is a flowering plant in the family Brassicaceae (the mustard family) with a documented history of use as a blue dye and medicinal plant. Its genus name, ''Isati ...

until it was replaced by the finer

indigo InterGlobe Aviation Limited (d/b/a IndiGo), is an India, Indian airline headquartered in Gurgaon, Haryana, India. It is the largest List of airlines of India, airline in India by passengers carried and fleet size, with a 64.1% domestic market ...

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 The United Nations (UN) is the Earth, global intergovernmental organization established by the signing of the Charter of the United Nations, UN Charter on 26 June 1945 with the stated purpose of maintaining international peace and internationa ...

and the

European Union The European Union (EU) is a supranational union, supranational political union, political and economic union of Member state of the European Union, member states that are Geography of the European Union, located primarily in Europe. The u ...

. In the United States and Europe, blue is the colour that both men and women are most likely to choose as their favourite, with at least one recent survey showing the same across several other countries, including China, Malaysia, and Indonesia. Past surveys in the US and Europe have found that blue is the colour most commonly associated with

harmony In music, harmony is the concept of combining different sounds in order to create new, distinct musical ideas. Theories of harmony seek to describe or explain the effects created by distinct pitches or tones coinciding with one another; harm ...

, confidence,

masculinity Masculinity (also called manhood or manliness) is a set of attributes, behaviors, and roles generally associated with men and boys. Masculinity can be theoretically understood as Social construction of gender, socially constructed, and there i ...

knowledge Knowledge is an Declarative knowledge, awareness of facts, a Knowledge by acquaintance, familiarity with individuals and situations, or a Procedural knowledge, practical skill. Knowledge of facts, also called propositional knowledge, is oft ...

intelligence Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. It can be described as t ...

, calmness,

distance Distance is a numerical or occasionally qualitative measurement of how far apart objects, points, people, or ideas are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two co ...

infinity Infinity is something which is boundless, endless, or larger than any natural number. It is denoted by \infty, called the infinity symbol. From the time of the Ancient Greek mathematics, ancient Greeks, the Infinity (philosophy), philosophic ...

, the

imagination Imagination is the production of sensations, feelings and thoughts informing oneself. These experiences can be re-creations of past experiences, such as vivid memories with imagined changes, or completely invented and possibly fantastic scenes ...

cold Cold is the presence of low temperature, especially in the atmosphere. In common usage, cold is often a subjectivity, subjective perception. A lower bound to temperature is absolute zero, defined as 0.00K on the Kelvin scale, an absolute t ...

, and

sadness Sadness is an emotional pain associated with, or characterized by, feelings of disadvantage, loss, despair, grief, helplessness, disappointment and sorrow. An individual experiencing sadness may become quiet or lethargic, and withdraw the ...

Etymology and linguistics

The

modern English Modern English, sometimes called New English (NE) or present-day English (PDE) as opposed to Middle and Old English, is the form of the English language that has been spoken since the Great Vowel Shift in England England is a Count ...

word ''blue'' comes from

Middle English Middle English (abbreviated to ME) is a form of the English language that was spoken after the Norman Conquest of 1066, until the late 15th century. The English language underwent distinct variations and developments following the Old English pe ...

or , from the

Old French Old French (, , ; ) was the language spoken in most of the northern half of France approximately between the late 8th Germanic origin, related to the Old High German">Germanic languages">Germanic origin, related to the Old High German word (meaning 'shimmering, lustrous').''Webster's Seventh New Collegiate Dictionary'' (1970). In heraldry, the word ''azure (heraldry), azure'' is used for ''blue''. In Russian language, Russian, Mongolian language, Mongolian, Irish language, Irish, and some other languages, there is no single word for blue, but rather different words for light blue (Russian: , ) and dark blue (Russian: , ) (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 . In Japanese, the word for blue (, ) is often used for colours that English speakers would refer to as green, such as the colour of a

traffic signal Traffic lights, traffic signals, or stoplights – also known as robots in South Africa, Zambia, and Namibia – are signaling devices positioned at intersection (road), road intersections, pedestrian crossings, and other locations in order t ...

meaning "go". In Lakota, the word is used for both blue and green, the two colours not being distinguished in older Lakota (for more on this subject, see Blue–green distinction in language). Linguistic research indicates that languages do not begin by having a word for the colour blue. Colour names often developed individually in natural languages, typically beginning with

black Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness.Eva Heller, ''P ...

and

white White is the lightest color and is achromatic (having no chroma). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully (or almost fully) reflect and scatter all the visible wa ...

(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.

Optics and colour theory

The term ''blue'' generally describes colours perceived by humans observing light with a dominant wavelength between approximately 450 and 495 nanometres. 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. Purer blues are in the middle of this range, e.g., around 470 nanometres.

Isaac Newton Sir Isaac Newton () was an English polymath active as a mathematician, physicist, astronomer, alchemist, theologian, and author. Newton was a key figure in the Scientific Revolution and the Age of Enlightenment, Enlightenment that followed ...

included blue as one of the seven colours in his first description of the

visible spectrum The visible spectrum is the spectral band, band of the electromagnetic spectrum that is visual perception, visible to the human eye. Electromagnetic radiation in this range of wavelengths is called ''visible light'' (or simply light). The optica ...

. 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

, the hue between blue and violet, as one of the separate colours, though today it is usually considered a hue of blue. 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

with reasonable accuracy. File:AdditiveColorMixing.svg, 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. File:Closeup of pixels.JPG, Red, green, and blue subpixels on a

liquid-crystal display A liquid-crystal display (LCD) is a flat-panel display or other Electro-optic modulator, electronically modulated optical device that uses the light-modulating properties of liquid crystals combined with polarizers to display information. Liq ...

. On the HSV colour wheel, the complement of blue is

yellow Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In t ...

; that is, a colour corresponding to an equal mixture of red and

green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a com ...

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).

LED

In 1993, high-brightness blue LEDs were demonstrated by Shuji Nakamura of Nichia Corporation. In parallel, Isamu Akasaki and Hiroshi Amano of Nagoya University were working on a new development which revolutionized LED lighting. Nakamura was awarded the 2006 Millennium Technology Prize for his invention. Nakamura, Hiroshi Amano and Isamu Akasaki were awarded the Nobel Prize in Physics in 2014 for the invention of an efficient blue LED.

Lasers

Laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

s 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. 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 Optogenetics is a biological technique to control the activity of neurons or other cell types with light. This is achieved by Gene expression, expression of Channelrhodopsin, light-sensitive ion channels, Halorhodopsin, pumps or Photoactivated ade ...

, Raman spectroscopy, and particle image velocimetry, due to their superior beam quality. Blue gas lasers are also still commonly used for

holography Holography is a technique that allows a wavefront to be recorded and later reconstructed. It is best known as a method of generating three-dimensional images, and has a wide range of other uses, including data storage, microscopy, and interfe ...

DNA sequencing DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, thymine, cytosine, and guanine. The ...

, optical pumping, among other scientific and medical applications.

Shades and variations

Blue is the colour of light between violet and

on the

. 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

, 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 These are the lists of colors; * List of colors: A–F * List of colors: G–M * List of colors: N–Z * List of colors (alphabetical) * List of colors by shade * List of color palettes * List of Crayola crayon colors * List of RAL colours * Lis ...

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.

Colourants

File:Egyptian blue.jpg, Egyptian blue File:Cobalt Blue.JPG, Cobalt blue File:Bleu phtalo.jpg, Copper phthalocyanine File:YInMn_Blue_-_cropped.jpg, YInMn blue File:Prussian blue.jpg, Prussian blue, Fe CN)">Cyanide.html" ;"title="e(Cyanide">CN) is the blue of blueprint">Cyanide">CN<_a>).html" ;"title="Cyanide.html" ;"title="e(Cyanide">CN)">Cyanide.html" ;"title="e(Cyanide">CN) is the blue of blueprints.

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 Jean-Antoine Watteau (, , ; baptised 10 October 1684died 18 July 1721) Alsavailablevia Oxford Art Online (subscription needed). was a French Painting, painter and Drawing, draughtsman whose brief career spurred the revival of interest in colour ...

, and later his successor

Nicolas Lancret Nicolas Lancret (; 22 January 1690 – 14 September 1743) was a List of French artists, French painter. Born in Paris, he was a brilliant depicter of light comedy which reflected the tastes and manners of French society during the Régence, regen ...

. It became immensely popular for the manufacture of wallpaper, and in the 19th century was widely used by French impressionist painters. 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. 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. In 1878 German chemists synthesized

. 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 Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

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. File:The Blue Boy.jpg, '' The Blue Boy'' (1770), featuring lapis lazuli, indigo, and cobalt colourants, File:Great Wave off Kanagawa2.jpg, '' The Great Wave off Kanagawa'' illustrates the use of Prussian blue File:Indigoproduktion BASF 1890.JPG, A synthetic indigo dye factory in Germany in 1890.

Dyes for textiles and food

Woad ''Isatis tinctoria'', also called woad (), dyer's woad, dyer's-weed, or glastum, is a flowering plant in the family Brassicaceae (the mustard family) with a documented history of use as a blue dye and medicinal plant. Its genus name, ''Isati ...

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. Blue dyes are organic compounds, both synthetic and natural. 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. Various

raspberry The raspberry is the edible fruit of several plant species in the genus ''Rubus'' of the Rosaceae, rose family, most of which are in the subgenus ''Rubus#Modern classification, Idaeobatus''. The name also applies to these plants themselves. Ras ...

-flavoured foods are dyed blue. This was done to distinguish

strawberry The garden strawberry (or simply strawberry; ''Fragaria × ananassa'') is a widely grown Hybrid (biology), hybrid plant cultivated worldwide for its fruit. The genus ''Fragaria'', the strawberries, is in the rose family, Rosaceae. The fruit ...

watermelon The watermelon (''Citrullus lanatus'') is a species of flowering plant in the family Cucurbitaceae, that has a large, edible fruit. It is a Glossary of botanical terms#scandent, scrambling and trailing vine-like plant, and is plant breeding ...

and

-flavoured foods. The company ICEE used Blue No. 1 for their blue raspberry ICEEs. File:Blue Raspberry Frozen Yogurt with White Chocolate Chips, Coconut, and Cherries.jpg, Blue Raspberry Frozen Yogurt with White Chocolate Chips, Coconut, and Cherries. File:Blue haribo jelly beans.jpg, Blue haribo jelly beans. Raspberry flavour. Bought in the UK. File:2019-11-09 19 29 30 A blue raspberry-flavored Jolly Rancher Hard Candy Stix after being unwrapped in the Dulles section of Sterling, Loudoun County, Virginia.jpg, A blue raspberry-flavoured Jolly Rancher Hard Candy Stix after being unwrapped in the Dulles section of Sterling, Loudoun County, Virginia. File:Indigo skeletal.svg, Chemical structure of

indigo dye Indigo dye is an organic compound with a distinctive indigo, blue color. Indigo is a natural dye obtained from the leaves of some plants of the Indigofera#Uses, ''Indigofera'' genus, in particular ''Indigofera tinctoria''. Dye-bearing ''Indigofer ...

, a widely produced blue dye. Blue jeans consist of 1–3% by weight of this

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

. File:C.I. Acid Blue 9.svg, upright=1.15, Chemical structure of C.I. Acid Blue 9, a dye commonly used in candies.

Pigments for painting and glass

Blue

pigment A pigment is a powder used to add or alter color or change visual appearance. Pigments are completely or nearly solubility, insoluble and reactivity (chemistry), chemically unreactive in water or another medium; in contrast, dyes are colored sub ...

s 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 Linseed oil, also known as flaxseed oil or flax oil (in its edible form), is a colorless to yellowish oil obtained from the dried, ripened seeds of the flax plant (''Linum usitatissimum''). The oil is obtained by pressing, sometimes followed by ...

, for

oil painting Oil painting is a painting method involving the procedure of painting with pigments combined with a drying oil as the Binder (material), binder. It has been the most common technique for artistic painting on canvas, wood panel, or oil on coppe ...

. Two inorganic but synthetic blue pigments are cerulean blue (primarily cobalt(II) stanate: ) and Prussian blue (milori blue: primarily ). The chromophore in blue

glass Glass is an amorphous (non-crystalline solid, non-crystalline) solid. Because it is often transparency and translucency, transparent and chemically inert, glass has found widespread practical, technological, and decorative use in window pane ...

and glazes is

cobalt Cobalt is a chemical element; it has Symbol (chemistry), symbol Co and atomic number 27. As with nickel, cobalt is found in the Earth's crust only in a chemically combined form, save for small deposits found in alloys of natural meteoric iron. ...

(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.

Blueprint A blueprint is a reproduction of a technical drawing or engineering drawing using a contact print process on light-sensitive sheets introduced by Sir John Herschel in 1842. The process allowed rapid and accurate production of an unlimited number ...

ing involves the production of Prussian blue in situ.

Inorganic compounds

Certain metal ions characteristically form blue solutions or blue salts. Of some practical importance,

is used to make the deep blue glazes and glasses. It substitutes for

silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...

aluminum Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...

ions in these materials. Cobalt is the blue chromophore in stained glass windows, such as those in Gothic cathedrals and in Chinese

porcelain Porcelain (), also called china, is a ceramic material made by heating Industrial mineral, raw materials, generally including kaolinite, in a kiln to temperatures between . The greater strength and translucence of porcelain, relative to oth ...

beginning in the

Tang dynasty The Tang dynasty (, ; zh, c=唐朝), or the Tang Empire, was an Dynasties of China, imperial dynasty of China that ruled from 618 to 907, with an Wu Zhou, interregnum between 690 and 705. It was preceded by the Sui dynasty and followed ...

. 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 Albert Einstein (14 March 187918 April 1955) was a German-born theoretical physicist who is best known for developing the theory of relativity. Einstein also made important contributions to quantum mechanics. His mass–energy equivalence f ...

in 1911. 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 1% 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 Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

and plant life in the water, which can make it look green; or by sediment, which can make it look brown. 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. Blue light is scattered more than other wavelengths by the gases in the

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

, hence our "blue planet". File:Top of Atmosphere.jpg, Earth's blue halo when seen from space File:Aerial perspective 1.JPG, Another example of Rayleigh scattering File:LightningVolt Deep Blue Sea.jpg, The sea

Minerals

Lapis-lazuli hg.jpg, Lapis-lazuli Azurite - New Nevada Lode, La Sal, Utah, USA.jpg, Azurite Natural ultramarine pigment.jpg, Natural ultramarine pigment Logan Sapphire SI.jpg, Logan sapphire Some of the most desirable gems are blue, including

sapphire Sapphire is a precious gemstone, a variety of the mineral corundum, consisting of aluminium oxide () with trace amounts of elements such as iron, titanium, cobalt, lead, chromium, vanadium, magnesium, boron, and silicon. The name ''sapphire ...

and tanzanite. Compounds of copper(II) are characteristically blue and so are many copper-containing minerals. Azurite (, 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

. It was extremely expensive, and in

Italian Renaissance The Italian Renaissance ( ) was a period in History of Italy, Italian history between the 14th and 16th centuries. The period is known for the initial development of the broader Renaissance culture that spread across Western Europe and marked t ...

art, it was often reserved for the robes of the

Virgin Mary Mary was a first-century Jewish woman of Nazareth, the wife of Saint Joseph, Joseph and the mother of Jesus. She is an important figure of Christianity, venerated under titles of Mary, mother of Jesus, various titles such as Perpetual virginity ...

Plants and fungi

File:Blaue Primeln.JPG, ''Primula acaulis'' File:Ipomoea August 2007-1.jpg, Morning glory ('' Ipomoea acuminata'') File:Vaccinium corymbosum Beeren.jpg, '' Vaccinium corymbosum'' File:Vinca minor Nashville.jpg, '' Vinca minor'' File:Delphinium denudatum 1.jpg, Blue Delphinium flower Lupinus-pilosus-2015-Zachi-Evenor-cropped02.jpg, Blue Lupme flower '' Lupinus pilosus'' File:Lactarius indigo 48568 edit.jpg, '' Lactarius indigo'' Intense efforts have focused on blue flowers and the possibility that natural blue colourants could be used as food dyes. Commonly, blue colours in plants are anthocyanins: "the largest group of water-soluble pigments found widespread in the plant kingdom". 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.

Animals

File:Morpho didius Male Dos MHNT.jpg, Morpho butterfly File:Indigo Bunting by Dan Pancamo 4.jpg, Indigo buntings have iridescent feathers. File:Mandrill-k-means.png, Blue facial ridges of

mandrill The mandrill (''Mandrillus sphinx'') is a large Old World monkey native to west central Africa. It is one of the most colorful mammals in the world, with red and blue skin on its face and posterior. The species is Sexual dimorphism, sexually ...

File:2009-03-29Dendrobates tinctorius azureus106.jpg, Blue poison dart frog File:Synchiropus splendidus 2 Luc Viatour cropped.png, The mandarin fish is one of few animal species with blue pigment Blue-pigmented animals are relatively rare. Examples of which include butterflies of the genus '' Nessaea'', where blue is created by pterobilin. 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''. Blue-pigmented organelles, known as "cyanosomes", exist in the chromatophores of at least two fish species, the mandarin fish and the picturesque dragonet. More commonly, blueness in animals is a structural colouration; an optical interference effect induced by organized nanometre-sized scales or fibres. Examples include the plumage of several birds like the blue jay and indigo bunting, the scales of butterflies like the morpho butterfly,

collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...

fibres in the skin of some species of monkey and opossum, and the iridophore cells in some fish and frogs.

Eyes

Blue eyes do not actually contain any blue pigment. Eye colour is determined by two factors: the

ation of the eye's iris and the

scattering In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiat ...

of light by the turbid medium in the stroma of the iris. 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. 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 The Baltic Sea is an arm of the Atlantic Ocean that is enclosed by the countries of Denmark, Estonia, Finland, Germany, Latvia, Lithuania, Poland, Russia, Sweden, and the North European Plain, North and Central European Plain regions. It is the ...

area and

Northern Europe The northern region of Europe has several definitions. A restrictive definition may describe northern Europe as being roughly north of the southern coast of the Baltic Sea, which is about 54th parallel north, 54°N, or may be based on other ge ...

, and are also found in Eastern, Central, and

Southern Europe Southern Europe is also known as Mediterranean Europe, as its geography is marked by the Mediterranean Sea. Definitions of southern Europe include some or all of these countries and regions: Albania, Andorra, Bosnia and Herzegovina, Bulgaria, C ...

. Blue eyes are also found in parts of

Western Asia West Asia (also called Western Asia or Southwest Asia) is the westernmost region of Asia. As defined by most academics, UN bodies and other institutions, the subregion consists of Anatolia, the Arabian Peninsula, Iran, Mesopotamia, the Armenian ...

, most notably in

Afghanistan Afghanistan, officially the Islamic Emirate of Afghanistan, is a landlocked country located at the crossroads of Central Asia and South Asia. It is bordered by Pakistan to the Durand Line, east and south, Iran to the Afghanistan–Iran borde ...

Syria Syria, officially the Syrian Arab Republic, is a country in West Asia located in the Eastern Mediterranean and the Levant. It borders the Mediterranean Sea to the west, Turkey to Syria–Turkey border, the north, Iraq to Iraq–Syria border, t ...

Iraq Iraq, officially the Republic of Iraq, is a country in West Asia. It is bordered by Saudi Arabia to Iraq–Saudi Arabia border, the south, Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq border, the east, the Persian Gulf and ...

, and

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

. In

Estonia Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Ru ...

, 99% of people have blue eyes. In

Denmark Denmark is a Nordic countries, Nordic country in Northern Europe. It is the metropole and most populous constituent of the Kingdom of Denmark,, . also known as the Danish Realm, a constitutionally unitary state that includes the Autonomous a ...

in 1978, only 8% of the population had brown eyes, though through immigration, today that number is about 11%. In

Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...

, about 75% have blue eyes. In the United States, as of 2006, 1 out of every 6 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. In the US, males are 3–5% more likely to have blue eyes than females.

History

In the ancient world

File:Lapis bowl Iran, AO 26477.jpg, Lapis lazuli bowl from Iran, end of 3rd – beginning of 2nd millennium BC (Louvre Museum) File:Tripodic goblet Louvre AO4079.jpg, Egyptian blue tripodic beaker imitating lapis lazuli. South Mesopotamia. (1399-1200 BC) File:WLA metmuseum Wall painting Polyphemus and Galaltea 4.jpg, 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,David Bomford and Ashok Roy, ''A Closer Look- Colour'' (2009), National Gallery Company, London, () in Shortugai, and in other mines in Badakhshan province in northeast

. Lapis lazuli artifacts, dated to 7570 BC, have been found at

Bhirrana Bhirrana, also Bhirdana and Birhana, ( IAST: Bhirḍāna) is an archaeological site, located in a small village in the Fatehabad district of the north Indian state of Haryana. Bhirrana's earliest archaeological layers contained two charcoal sam ...

, which is the oldest site of

Indus Valley civilisation The Indus Valley Civilisation (IVC), also known as the Indus Civilisation, was a Bronze Age civilisation in the Northwestern South Asia, northwestern regions of South Asia, lasting from 3300 Common Era, BCE to 1300 BCE, and in i ...

. Lapis was highly valued by the Indus Valley Civilisation (7570–1900 BC). Lapis beads have been found at

Neolithic The Neolithic or New Stone Age (from Ancient Greek, Greek 'new' and 'stone') is an archaeological period, the final division of the Stone Age in Mesopotamia, Asia, Europe and Africa (c. 10,000 BCE to c. 2,000 BCE). It saw the Neolithic Revo ...

burials in

Mehrgarh Mehrgarh is a Neolithic archaeological site situated on the Kacchi Plain of Balochistan, Pakistan, Balochistan in Pakistan. It is located near the Bolan Pass, to the west of the Indus River and between the modern-day Pakistani cities of Quetta, ...

, the

Caucasus The Caucasus () or Caucasia (), is a region spanning Eastern Europe and Western Asia. It is situated between the Black Sea and the Caspian Sea, comprising parts of Southern Russia, Georgia, Armenia, and Azerbaijan. The Caucasus Mountains, i ...

, and as far away as

Mauritania Mauritania, officially the Islamic Republic of Mauritania, is a sovereign country in Maghreb, Northwest Africa. It is bordered by the Atlantic Ocean to the west, Western Sahara to Mauritania–Western Sahara border, the north and northwest, ...

. It was used in the funeral mask of Tutankhamun (1341–1323 BC). 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 The Hebrew Bible or Tanakh (;"Tanach"
. '' tekhelet'. Reds, blacks, browns, and ochres are found in cave paintings from the Upper

Paleolithic The Paleolithic or Palaeolithic ( years ago) ( ), also called the Old Stone Age (), is a period in human prehistory that is distinguished by the original development of stone tools, and which represents almost the entire period of human prehist ...

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. The earliest known blue dyes were made from plants –

in Europe,

in Asia and Africa, while blue pigments were made from minerals, usually either lapis lazuli or azurite, and required more. Blue glazes posed still another challenge since the early blue dyes and pigments were not thermally robust. In , the blue glaze Egyptian blue was introduced for ceramics, as well as many other objects.Chase, W.T. 1971, "Egyptian blue as a pigment and ceramic material." In: R. Brill (ed.) ''Science and Archaeology''. Cambridge, Mass: MIT Press. 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 Gaius Plinius Secundus (AD 23/24 79), known in English as Pliny the Elder ( ), was a Roman Empire, Roman author, Natural history, naturalist, and naval and army commander of the early Roman Empire, and a friend of the Roman emperor, emperor Vesp ...

(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. The Romans made extensive use of indigo and Egyptian blue pigment, as evidenced, in part, by frescos in

Pompeii Pompeii ( ; ) was a city in what is now the municipality of Pompei, near Naples, in the Campania region of Italy. Along with Herculaneum, Stabiae, and Villa Boscoreale, many surrounding villas, the city was buried under of volcanic ash and p ...

. The Romans had many words for varieties of blue, including , , , , , , , and , but two words, both of foreign origin, became the most enduring; , from the Germanic word ''blau'', which eventually became ''bleu'' or blue; and , from the Arabic word , which became azure. Blue was widely used in the decoration of churches in the Byzantine Empire. 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.

In the Middle Ages

File:Vitraux Saint-Denis 190110 19.jpg, Stained glass window at Saint Denis Basilica (1130–1140), coloured with cobalt blue File:Vitrail Chartres Notre-Dame 210209 1.jpg, Detail of the Blue Virgin Window, Chartres Cathedral (12th c.) File:Wilton diptych.jpg, The Wilton Diptych (1395–1399). The

was traditionally shown in blue(14th c.) In the art and life of Europe during the early

, 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. He installed

stained glass Stained glass refers to coloured glass as a material or art and architectural works created from it. Although it is traditionally made in flat panels and used as windows, the creations of modern stained glass artists also include three-dimensio ...

windows coloured with

, 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 . In the years that followed even more elegant blue stained glass windows were installed in other churches, including at Chartres Cathedral and

Sainte-Chapelle The Sainte-Chapelle (; ) is a royal chapel in the Gothic style, within the medieval Palais de la Cité, the residence of the Kings of France until the 14th century, on the Île de la Cité in the River Seine in Paris, France. Construction b ...

in Paris. 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 According to legends, King Arthur (; ; ; ) was a king of Great Britain, Britain. He is a folk hero and a central figure in the medieval literary tradition known as the Matter of Britain. In Wales, Welsh sources, Arthur is portrayed as a le ...

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 The ''fleur-de-lis'', also spelled ''fleur-de-lys'' (plural ''fleurs-de-lis'' or ''fleurs-de-lys''), is a common heraldic charge in the (stylized) shape of a lily (in French, and mean and respectively). Most notably, the ''fleur-de-lis'' ...

or lilies. Blue had come from obscurity to become the royal colour.

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 Raffaello Sanzio da Urbino (; March 28 or April 6, 1483April 6, 1520), now generally known in English as Raphael ( , ), was an Italian painter and architect of the High Renaissance. List of paintings by Raphael, His work is admired for its cl ...

was a master of this technique, carefully balancing the reds and the blues so no one colour dominated the picture. 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. File:Oliver Richard Sackville Earl of Dorset 1616.jpg, Portrait of Richard Sackville (1616), using three expensive blues, including ultramarine for his stockings File:MET DP251168.jpg,

Ming dynasty The Ming dynasty, officially the Great Ming, was an Dynasties of China, imperial dynasty of China that ruled from 1368 to 1644, following the collapse of the Mongol Empire, Mongol-led Yuan dynasty. The Ming was the last imperial dynasty of ...

, Porcelain vase painted with cobalt blue under transparent glaze. (15th c.) (Metropolitan Museum) File:Delftware plaque with New Testament scene 002.jpg, Delftware plaque with cobalt blue painting (1683) (Rijksmuseum, Amsterdam) File:Portrait of Louis XIV of France in Coronation Robes (by Hyacinthe Rigaud) - Louvre Museum.jpg, Portrait of King

Louis XIV of France LouisXIV (Louis-Dieudonné; 5 September 16381 September 1715), also known as Louis the Great () or the Sun King (), was King of France from 1643 until his death in 1715. His verified reign of 72 years and 110 days is the List of longest-reign ...

in coronation robes, by Hyacinthe Rigaud (c. 1700) (Louvre Museum) File:Urn with cover MET DP104608.jpg, Urn by Josiah Wedgwood (1780s) (Metropolitan Museum) File:Queen Maria I of Portugal (1734-1816) in an 18th century painting.jpg, Queen Maria I of Portugal (late 1700s) File:Johannes Vermeer - Girl with a Pearl Earring - WGA24666.jpg, '' Girl with a Pearl Earring'' by Johannes Vermeer features ultramarine pigment 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 Delft () is a List of cities in the Netherlands by province, city and Municipalities of the Netherlands, municipality in the Provinces of the Netherlands, province of South Holland, Netherlands. It is located between Rotterdam, to the southeast, ...

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.

19th-20th century

File:BrummellDighton1805.jpg, Beau Brummel (1776–1840) introduced the ancestor of the modern blue suit File:D. Maria II (1834) - Joaquim Rafael (Museu Militar de Lisboa).png, Queen Maria II of Portugal in a blue and gold embroidered gown (1835) File:A Miner in His Cabin.jpg, A California gold miner in blue jeans (1853) File:Ferdinand Krumholz Isabel do Brasil 1853.jpg, Isabel, Princess Imperial of Brazil in light blue gown (1853) File:New York Metropolitan Police Uniforms 1871.jpg, 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 Denim is a sturdy cotton warp-faced textile in which the weft passes under two or more Warp (weaving), warp threads. This twill weave produces a diagonal ribbing that distinguishes it from cotton duck. Denim, as it is recognized today, was f ...

work clothing in the California gold fields. The invention was funded by San Francisco entrepreneur Levi Strauss, and spread around the world. . File:Starry Night Over the Rhone.jpg, 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. File:Matisse Conversation.jpg, '' The Conversation'' by

Henri Matisse Henri Émile Benoît Matisse (; 31 December 1869 – 3 November 1954) was a French visual arts, visual artist, known for both his use of colour and his fluid and original draughtsmanship. He was a drawing, draughtsman, printmaking, printmaker, ...

(1908–1912) 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 Pablo Diego José Francisco de Paula Juan Nepomuceno María de los Remedios Cipriano de la Santísima Trinidad Ruiz y Picasso (25 October 1881 – 8 April 1973) was a Spanish painter, sculptor, printmaker, Ceramic art, ceramicist, and Scenic ...

, Pavel Kuznetsov and the Blue Rose art group, and Kandinsky and Der Blaue Reiter (The Blue Rider) school.Wassily Kandinsky, M. T. Sadler (Translator) ''Concerning the Spiritual in Art''. Dover Publ. (Paperback). 80 pp. .

expressed deep emotions with blue, "A certain blue penetrates your soul." 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".

In society and culture

Uniforms

File:HoratioNelson1.jpg, Navy blue derives its name from the uniform of

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

officers File:TSA agents, ca. 2016.jpg, Transportation Security Administration agents File:2010. Донецк. Карнавал на день города 010.jpg, Ukrainian police officer in Donetsk File:PM do Rio muda o comando de 25 UPPs.jpg, Officers of the Military Police of Rio de Janeiro State, Brazil In the 17th century. The Prince-Elector of Brandenburg,

Frederick William I of Prussia Frederick William I (; 14 August 1688 – 31 May 1740), known as the Soldier King (), was King in Prussia and Elector of Brandenburg from 1713 until his death in 1740, as well as Prince of Neuchâtel. Born in Berlin, he was raised by the Hugu ...

, chose Prussian blue as the new colour of Prussian military uniforms, because it was made with

, a local crop, rather than

Indigo InterGlobe Aviation Limited (d/b/a IndiGo), is an India, Indian airline headquartered in Gurgaon, Haryana, India. It is the largest List of airlines of India, airline in India by passengers carried and fleet size, with a 64.1% domestic market ...

, 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. In 1748, the

adopted a dark shade of blue for the uniform of officers.Heller (2010) p.32 It was first known as marine blue, now known as navy blue. The militia organized by

George Washington George Washington (, 1799) was a Founding Fathers of the United States, Founding Father and the first president of the United States, serving from 1789 to 1797. As commander of the Continental Army, Washington led Patriot (American Revoluti ...

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. 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. It was also adopted at about the same time for the uniforms of the officers of the

New York City Police Department The City of New York Police Department, also referred to as New York City Police Department (NYPD), is the primary law enforcement agency within New York City. Established on May 23, 1845, the NYPD is the largest, and one of the oldest, munic ...

Gender

Blue is used to represent males. Beginning as a trend the mid-19th century and applying primarily to clothing, gendered associations with blue became more widespread from the 1950s. The colour became associated with males after

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. File:ANAB767300Restroomsign.jpg, This restroom sign on an

All Nippon Airways (ANA) is a Japanese airline headquartered in Minato, Tokyo. ANA operates services to both domestic and international destinations and is Japan's largest airline, ahead of its main rival flag carrier Japan Airlines. the airline has approximate ...

Boeing 767-300 uses pink for the female gender and blue for the male gender. File:Gender Reveal Cake (28005690402).jpg, Cake using blue to represent the male sex. File:Fynn Esser 2013-11-18 21-47.jpg, Baby blue newborn male clothing

Religion

File:Sri Mariamman Temple Singapore 2 amk.jpg, In

Hinduism Hinduism () is an Hypernymy and hyponymy, umbrella term for a range of Indian religions, Indian List of religions and spiritual traditions#Indian religions, religious and spiritual traditions (Sampradaya, ''sampradaya''s) that are unified ...

Krishna Krishna (; Sanskrit language, Sanskrit: कृष्ण, ) is a major deity in Hinduism. He is worshipped as the eighth avatar of Vishnu and also as the Supreme God (Hinduism), Supreme God in his own right. He is the god of protection, c ...

is depicted with blue skin File:Reknown blue domes of the Church dedicated to St. Spirou in Firostefani, Santorini island (Thira), Greece.jpg, Blue domes of the Church dedicated to St. Spirou in Firostefani, Santorini island (Thira), Greece. File:Mezquita Shah, Isfahán, Irán, 2016-09-20, DD 64.jpg, Persian blue in Shah mosque (16th c.) in

Isfahan Isfahan or Esfahan ( ) is a city in the Central District (Isfahan County), Central District of Isfahan County, Isfahan province, Iran. It is the capital of the province, the county, and the district. It is located south of Tehran. The city ...

, Iran * Blue in Judaism: In the

Torah The Torah ( , "Instruction", "Teaching" or "Law") is the compilation of the first five books of the Hebrew Bible, namely the books of Genesis, Exodus, Leviticus, Numbers and Deuteronomy. The Torah is also known as the Pentateuch () ...

, the

Israelites Israelites were a Hebrew language, Hebrew-speaking ethnoreligious group, consisting of tribes that lived in Canaan during the Iron Age. Modern scholarship describes the Israelites as emerging from indigenous Canaanites, Canaanite populations ...

were commanded to put fringes, '' tzitzit'', on the corners of their garments, and to weave within these fringes a "twisted thread of blue (''tekhelet'')". In ancient days, this blue thread was made from a dye extracted from a Mediterranean snail called the ''hilazon''.

Maimonides Moses ben Maimon (1138–1204), commonly known as Maimonides (, ) and also referred to by the Hebrew acronym Rambam (), was a Sephardic rabbi and Jewish philosophy, philosopher who became one of the most prolific and influential Torah schola ...

claimed that this blue was the colour of "the clear noonday sky";

Rashi Shlomo Yitzchaki (; ; ; 13 July 1105) was a French rabbi who authored comprehensive commentaries on the Talmud and Hebrew Bible. He is commonly known by the List of rabbis known by acronyms, Rabbinic acronym Rashi (). Born in Troyes, Rashi stud ...

, the colour of the evening sky. According to several rabbinic sages, blue is the colour of God's Glory. 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. (The

Hebrew Hebrew (; ''ʿÎbrit'') is a Northwest Semitic languages, Northwest Semitic language within the Afroasiatic languages, Afroasiatic language family. A regional dialect of the Canaanite languages, it was natively spoken by the Israelites and ...

word for glory) Many items in the ''

Mishkan According to the Hebrew Bible, the tabernacle (), also known as the Tent of the Congregation (, also Tent of Meeting), was the portable earthly dwelling of God used by the Israelites from the Exodus until the conquest of Canaan. Moses was instru ...

'', the portable sanctuary in the wilderness, such as the '' menorah'', many of the vessels, and the

Ark of the Covenant The Ark of the Covenant, also known as the Ark of the Testimony or the Ark of God, was a religious storage chest and relic held to be the most sacred object by the Israelites. Religious tradition describes it as a wooden storage chest decorat ...

, were covered with blue cloth when transported from place to place. * Blue in

Christianity Christianity is an Abrahamic monotheistic religion, which states that Jesus in Christianity, Jesus is the Son of God (Christianity), Son of God and Resurrection of Jesus, rose from the dead after his Crucifixion of Jesus, crucifixion, whose ...

: Blue is particularly associated with the

. This was the result of a decree of

Pope Gregory I Pope Gregory I (; ; – 12 March 604), commonly known as Saint Gregory the Great (; ), was the 64th Bishop of Rome from 3 September 590 until his death on 12 March 604. He is known for instituting the first recorded large-scale mission from Ro ...

(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.Heller, "Psychologie de la Colour - Effets et Symboliques", (2009),p. 32 * Blue in

: Many of the gods are depicted as having blue-coloured skin, particularly those associated with

Vishnu Vishnu (; , , ), also known as Narayana and Hari, is one of the Hindu deities, principal deities of Hinduism. He is the supreme being within Vaishnavism, one of the major traditions within contemporary Hinduism, and the god of preservation ( ...

, who is said to be the preserver of the world, and thus intimately connected to water.

and

Rama Rama (; , , ) is a major deity in Hinduism. He is worshipped as the seventh and one of the most popular avatars of Vishnu. In Rama-centric Hindu traditions, he is considered the Supreme Being. Also considered as the ideal man (''maryāda' ...

, Vishnu's avatars, are usually depicted with blue skin.

Shiva Shiva (; , ), also known as Mahadeva (; , , Help:IPA/Sanskrit, ɐɦaːd̪eːʋɐh and Hara, is one of the Hindu deities, principal deities of Hinduism. He is the God in Hinduism, Supreme Being in Shaivism, one of the major traditions w ...

, the destroyer deity, is also depicted in a light-blue hue, and is called '' Nīlakaṇṭha'', 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). * Blue in

Sikhism Sikhism is an Indian religion and Indian philosophy, philosophy that originated in the Punjab region of the Indian subcontinent around the end of the 15th century CE. It is one of the most recently founded major religious groups, major religio ...

: The Akali Nihangs warriors wear all-blue attire.

Guru Gobind Singh Guru Gobind Singh (; born Gobind Das; 22 December 1666 – 7 October 1708) was the tenth and last human Sikh gurus, Sikh Guru. He was a warrior, poet, and philosopher. In 1675, at the age of nine he was formally installed as the leader of the ...

also has a blue roan

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...

. The Sikh Rehat Maryada states that the

Nishan Sahib The Nishan Sahib (), also known as the Sikh flag, is used to represent the Sikh people worldwide. In 1936, the Shiromani Gurdwara Parbandhak Committee ratified the Rehat, Sikh Rehet Maryada, which states its colour as either basanti (xanthic) ...

hoisted outside every Gurudwara should be xanthic (Basanti in Punjabi) or greyish blue (modern day navy blue) (Surmaaee in Punjabi) colour. *Blue in

Paganism Paganism (, later 'civilian') is a term first used in the fourth century by early Christians for people in the Roman Empire who practiced polytheism, or ethnic religions other than Christianity, Judaism, and Samaritanism. In the time of the ...

: Blue is associated with peace, truth, wisdom, protection, and patience. It helps with healing, psychic ability, harmony, and understanding.

Sports

File:Italy Team - Rome, 1965.jpg, The Italian national football team File:Serbia national volleyball team at the 2012 Summer Olympics (7913882066).jpg, Serbian national volleyball team, 2012 Olympics File:Jack White, Duke Blue Devils.jpg, Basketball player for the Blue Devils at Cassell Coliseum 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 France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

are known as ''Les Bleus'' (the Blues). Similarly,

Argentina Argentina, officially the Argentine Republic, is a country in the southern half of South America. It covers an area of , making it the List of South American countries by area, second-largest country in South America after Brazil, the fourt ...

Italy Italy, officially the Italian Republic, is a country in Southern Europe, Southern and Western Europe, Western Europe. It consists of Italian Peninsula, a peninsula that extends into the Mediterranean Sea, with the Alps on its northern land b ...

, and

Uruguay Uruguay, officially the Oriental Republic of Uruguay, is a country in South America. It shares borders with Argentina to its west and southwest and Brazil to its north and northeast, while bordering the Río de la Plata to the south and the A ...

wear blue shirts. The

Asian Football Confederation The Asian Football Confederation (AFC) is the governing body of association football, beach soccer, and futsal in most countries and territories in Asia. The AFC was formed in 1954. It has 47 members. The Asian Ladies Football Confederation ( ...

and the

Oceania Football Confederation The Oceania Football Confederation (OFC) is one of the six continental confederations of international association football. The OFC has 13 members, 11 of which are full members and two which are associate members not affiliated with FIFA. It ...

use blue text on their logos. Blue is well represented in

baseball Baseball is a bat-and-ball games, bat-and-ball sport played between two team sport, teams of nine players each, taking turns batting (baseball), batting and Fielding (baseball), fielding. The game occurs over the course of several Pitch ...

( Blue Jays),

basketball Basketball is a team sport in which two teams, most commonly of five players each, opposing one another on a rectangular Basketball court, court, compete with the primary objective of #Shooting, shooting a basketball (ball), basketball (appro ...

, and

American football American football, referred to simply as football in the United States and Canada and also known as gridiron football, is a team sport played by two teams of eleven players on a rectangular American football field, field with goalposts at e ...

, and

Ice hockey Ice hockey (or simply hockey in North America) is a team sport played on ice skates, usually on an Ice rink, ice skating rink with Ice hockey rink, lines and markings specific to the sport. It belongs to a family of sports called hockey. Tw ...

. 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".

Politics

File:Flag of the United Nations.svg, Flag of the

, approximates "sky blue" File:Flag of Europe.svg, Flag of the

is "reflex blue", a medium dark blue File:Red states and blue states of the US based on data from the 2008, 2012, 2016 and 2020 presidential elections.svg, A presidential-election map of the US, 2008–2020. 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

, the

, and

NATO The North Atlantic Treaty Organization (NATO ; , OTAN), also called the North Atlantic Alliance, is an intergovernmental organization, intergovernmental Transnationalism, transnational military alliance of 32 Member states of NATO, member s ...

.Heller, "Psychologie de la Couleur" pp. 36-37 In politics, blue is often used as the colour of conservative parties, contrasting with the red associated with left-wing parties. Some conservative parties that use the colour blue include the

Conservative Party (UK) The Conservative and Unionist Party, commonly the Conservative Party and colloquially known as the Tories, is one of the two main political parties in the United Kingdom, along with the Labour Party (UK), Labour Party. The party sits on the Cent ...

Conservative Party of Canada The Conservative Party of Canada (CPC; , ), sometimes referred to as the Tories, is a Government of Canada, federal List of political parties in Canada, political party in Canada. It was formed in 2003 by the merger of the two main Right-wing ...

Liberal Party of Australia The Liberal Party of Australia (LP) is the prominent centre-right political party in Australia. It is considered one of the two major parties in Australian politics, the other being the Australian Labor Party (ALP). The Liberal Party was fo ...

, Liberal Party of Brazil, and Likud of Israel. However, in some countries, blue is not associated main conservative party. In the United States, the liberal Democratic Party is associated with blue, while the conservative Republican Party is associated with red. US states which have been won by the Democratic Party in four consecutive presidential elections are termed "blue states", while those that have been won by the Republican Party are termed "red states".

South Korea South Korea, officially the Republic of Korea (ROK), is a country in East Asia. It constitutes the southern half of the Korea, Korean Peninsula and borders North Korea along the Korean Demilitarized Zone, with the Yellow Sea to the west and t ...

also uses this colour model, with the Democratic Party on the left using blue and the People Power Party on the right using red.

References

Works cited

* (page numbers refer to the French translation) * * * * * * *

External links

* *
"Friday essay: from the Great Wave to Starry Night, how a blue pigment changed the world", By Hugh Davies, theconversation.com
{{Authority control Optical spectrum Primary colors Rainbow colors Secondary colors Shades of violet Web colors Masculinity

Etymology and linguistics

Optics and colour theory

LED

Lasers

Shades and variations

As a structural colour

Colourants

Artificial blues

Dyes for textiles and food

Pigments for painting and glass

Inks

Inorganic compounds

In nature

Sky and sea

Minerals

Plants and fungi

Animals

Eyes

History

In the ancient world

In the Middle Ages

Renaissance through 18th century

19th-20th century

In society and culture

Uniforms

Gender

Religion

Sports

Politics

See also

References

Works cited

Further reading

External links