Cobalt is a cool, slightly desaturated blue, historically made using cobalt salts. The blue seen on many glassware pieces is cobalt blue and is used widely by artists. It was discovered by Louis-Jacques Thenard in 1802. It is extraordinarily unstable. Chemically it is a cobalt(II) oxide-aluminium oxide, or cobalt aluminate. Commercial production began in France in 1807. John Varley suggested it as a good substitution for ultramarine blue for painting skies. Authors of web pages have a variety of options available for specifying colors for elements of web documents. ... The RGB color model utilizes the additive model in which red, green and blue light are combined in various ways to create other colors. ... Red is any of a number of similar colors at the lowest frequencies of light discernible by the human eye. ... Green is any of a number of similar colors. ... Blue is any of a number of similar colors. ... Cyan, magenta, yellow, and key (black) CMYK (sometimes YMCK or CYM) is a subtractive color model used in color printing. ... Cyan is a pure spectral color, but the same hue can also be generated by mixing equal amounts of green and blue light. ... Magenta is a color made up of red and blue light. ... Yellow is any color of light that stimulates both the red and green cone cells of the retina, but not the blue cone cells. ... Black is a color with several subtle differences in meaning. ... The HSV (Hue, Saturation, Value) model, also called HSB (Hue, Saturation, Brightness), defines a color space in terms of three constituent components: HSV color space as a color wheel Hue, the color type (such as red, blue, or yellow): Ranges from 0-360 (but normalized to 0-100% in some... e gradation of color; for the city in Vietnam, see Huế. A hue refers to the gradation of color within the optical spectrum, or visible spectrum, of light. ... Scale of saturation (0% at bottom). ... Brightness is an attribute of visual perception in which a source appears to emit a given amount of light. ... General Name, Symbol, Number cobalt, Co, 27 Chemical series transition metals Group, Period, Block 9, 4, d Appearance metallic with gray tinge Atomic mass 58. ... Blue is any of a number of similar colors. ... Louis Jacques Thénard. ... Flash point Non-flammable. ... John Varley (1778‑1842) was an English watercolour painter and astrologer, and a close friend of William Blake, the poet/painter/mystic. ... Natural ultramarine. ...

Image File history File links Cobalt_blue_hue. ...

See also

• List of colors

The following is a partial list of colors with associated articles. ...

External links

• History of Cobalt blue