Blue-green much larger color gamut than RYB color space. The first recorded use of "cyan" as a color name in English was in 1879. The color turquoise, a representation of the color of the semi-precious stone turquoise. The first recorded use of "turquoise" as a color name in English was in 1573. The color "turquoise" is a light tone of blue-green. Green-blue had been a Crayola color since 1958. It was continued as a Crayola crayon color until 1990. One definition of the color is in the Munsell color system (Munsell 5BG) although there is wide-spread acceptance and knowledge of the
Green light source typically has a spectral power distribution dominated by energy with a wavelength of roughly 487570 nm. Human eyes have color receptors known as cone cells, of which there are three types. In some cases, one is missing or faulty, which can cause color blindness, including the common inability to distinguish red and yellow from green, known as deuteranopia or redgreen color blindness. Green is restful to the eye. Studies show that a green environment can reduce fatigue. In the subtractive color system, used in painting and color printing, green is created by a combination of yellow and blue,