Blue
A primary colour seen in the sky and sea, used since ancient times in art and dye
Blue is a primary colour in both traditional and modern colour systems, found between violet and cyan in the visible spectrum. Its name comes from Old French and Germanic roots. Blue has been valued for thousands of years in art, decoration, and clothing, with sources ranging from lapis lazuli to synthetic dyes. It is commonly linked with harmony and is a favourite colour in many countries.
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- Blue is a primary colour in both art and digital systems
- The sky and sea appear blue due to light scattering
- Lapis lazuli and indigo were historic sources of blue
- Synthetic blue dyes replaced natural sources in the 19th century
- Blue is the favourite colour in many countries
What colour is Blue?
Blue is one of the main colours in both the RGB (used for screens) and RYB (used in painting) systems. It sits between violet and cyan in the spectrum, with a wavelength of about 450–495 nanometres. The sky and sea look blue due to how light scatters in the atmosphere and water. Blue can range from deep, dark shades like navy or ultramarine to lighter tints such as sky blue or azure. It stands apart from neighbouring colours by its coolness and is often seen as calm or distant.
Where does Blue come from?
The English word 'blue' comes from Middle English and Old French, with roots in a Germanic word meaning 'shimmering' or 'lustrous'. In heraldry, blue is called 'azure'. Many languages have different words for light and dark blue, or use the same word for blue and green. Blue was the last main colour to be named in many languages, often only after blue pigments became available.
How Blue is defined
Blue as a colour is defined by its place in the spectrum, but blue pigments and dyes have been made from various sources. Ancient Egyptians created the first artificial blue pigment, Egyptian blue, from sand, copper, and natron. Lapis lazuli was ground for ultramarine. Later, synthetic pigments like Prussian blue, cobalt blue, and artificial ultramarine were developed. Today, blue dyes for textiles and food are mostly synthetic.
Where Blue is used
Blue has been used in art and decoration since ancient times. Lapis lazuli was prized in Egypt and the Renaissance. Chinese artists used cobalt blue for porcelain. Medieval European cathedrals featured blue stained glass. Blue dyes coloured clothing, from woad in Europe to indigo from America. In the 19th and 20th centuries, blue became common in uniforms and business suits, and is now widely used in flags, digital screens, and printing.
What Blue means
Blue is often associated with harmony and calmness, especially in Europe and the United States. Surveys show it is the favourite colour of many people in these regions as well as in China, Malaysia, and Indonesia. It is also linked with confidence, knowledge, and sometimes sadness. The choice of blue for the United Nations and European Union flags reflects its association with harmony.
Blue around the world
What the blue family means from country to country.
Lapis lazuli has been mined in the mountains of Badakhshan for more than six thousand years. Ground to powder it gave ultramarine, the costliest blue in European painting.
Royalty and powerSacred and holyAweSource: Lapis lazuliThe chadari is a full-length covering for women with a mesh panel over the eyes. In Kabul and the north it is most often a light blue.
Protection and healingSource: BurqaThe blue band of the flag stands for the wish of the Armenian people to live under peaceful skies. The red above it is for the highlands and the struggle to survive.
Politics and protestHopeSource: Flag of ArmeniaThe flag is sky blue, white and sky blue, created by Manuel Belgrano in 1812. National teams are called the Albiceleste, the white and sky blue.
Politics and protestPrideSource: Flag of ArgentinaBoca Juniors play in blue and gold. The club's story is that in 1907 it took the colours of the flag of the next ship into port, which was Swedish.
Festival and celebrationPrideSource: Boca JuniorsTo be true blue is to be honestly and loyally Australian. The phrase is older than the country, but Australians have made it their own.
Politics and protestTrustSource: True Blue (John Williamson song)Shades and relatives of Blue
Blue includes a wide range of shades. Indigo and ultramarine are closer to violet, while azure and sky blue are lighter. Cyan sits between blue and green. Darker blues include navy and Prussian blue, while lighter tints include Egyptian blue. Some languages do not distinguish between blue and green, or have separate words for light and dark blue.
Colours that go with Blue
Harmonies are worked out from the value #0000FF. Contrast ratios follow the WCAG 2 formula.
Questions people ask about Blue
What colour is blue?
Blue is a primary colour that sits between violet and cyan in the visible spectrum, with a wavelength of about 450–495 nanometres. It is seen in the sky and the sea.
Where does the name 'blue' come from?
The word 'blue' comes from Middle English and Old French, with roots in a Germanic word meaning 'shimmering' or 'lustrous'.
What are some famous sources of blue pigment?
Historic sources include lapis lazuli for ultramarine, Egyptian blue made from sand and copper, indigo dye from plants, and later synthetic pigments such as Prussian blue and cobalt blue.
Why do the sky and sea look blue?
The blue appearance of the sky and sea is due to Rayleigh scattering, an optical effect where shorter blue wavelengths of light scatter more than others in the atmosphere or water.
Is blue a favourite colour?
Yes, surveys in the United States, Europe, and several Asian countries show blue is often chosen as the favourite colour by both men and women.
Good reading and sources
- Encyclopaedia BritannicaArticle
- When red meant Democratic and blue was Republican. A brief history of TV electoral mapsLos Angeles Times, Article
- The Science of ColorSmithsonian, Article
The facts on this page come from the Wikipedia article "Blue", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). Rang rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.
It may contain mistakes. The swatch is an approximation: named colours are not fixed standards, and every screen shows them a little differently. If something is wrong, tell us. Last refreshed 2026-10-03.
More of the blue family
All of blue
#007FFF
Azure
A clear sky blue, halfway between blue and cyan on the colour wheelNamed shade · 🇮🇹 Italy +2
#87CEEB
Sky blue
A light blue named for the colour of a clear daytime skyNamed shade · 🇦🇷 Argentina +5
#000080
Navy blue
A deep blue shade named for the uniforms of the Royal NavyNamed shade · 🇺🇸 United States +2
#002366
Royal blue
A strong, deep blue linked with royalty and national flagsNamed shade · 🇫🇷 France +4
#191970
Midnight blue
A deep blue that recalls the sky late at night under moonlightNamed shade
#B0E0E6
Powder blue
A pale blue once made from powdered cobalt glass, now a standard paint and web colourNamed shade
#6699CC
Blue-gray
A cool-toned mix of blue and grey seen in nature, art, and uniformsNamed shade
#4682B4
Steel blue
A subdued blue-grey shade named for the colour of blued steelNamed shade