INDIGOIndigo is the color on the spectrum between about 450 and 420 nanometers in wavelength, placing it between blue and violet. Color scientists do not usually recognize indigo as a significant color category, and generally classify wavelengths shorter than about 450 nm as violet.
[1] Indigo and violet are different from purple, which cannot be seen on the electromagnetic spectrum but can be achieved by mixing blue light with red light.
One can see spectral indigo by looking at the reflection of a fluorescent tube in a non-recordable compact disc. This works because the CD functions as a diffraction grating, and a fluorescent lamp generally has a peak at 435.833 nm (from mercury), as is visible on the fluorescent lamp spectrum.
One can see spectral indigo by looking at the reflection of a fluorescent tube in a non-recordable compact disc. This works because the CD functions as a diffraction grating, and a fluorescent lamp generally has a peak at 435.833 nm (from mercury), as is visible on the fluorescent lamp spectrum.
Like many other colors, indigo gets its name from an object in the natural world—the plant named indigo once used for dyeing cloth
FOOD
The outer skin of many varieties of eggplant is colored pigment indigo.
So called "purple" carrots and potatoes are actually colored pigment indigo.
