Any wavelength of less than 450 nm is simply referred to as violet. Here are the color frequency wavelengths:

• Violet 380–450 nm
• Indigo is about 435 nm
• Blue 450–475 nm
• Cyan 476–495 nm
• Green 495–570 nm
• Yellow 570–590 nm
• Orange 590–620 nm
• Red 620–750 nm

Isaac Newton originally divided the color spectrum into the seven colors: red, orange, yellow, green, blue, indigo, and violet. Although indigo is traditionally one of seven divisions in the optical spectrum, the human eye is relatively insensitive to indigo’s frequencies. In fact, some well-sighted people cannot distinguish indigo from blue or violet.

The color electric indigo is the brightest version of indigo on a computer screen, and is located between Web blue and violet on the RGB color wheel. Deep indigo is another name for the Web color blue/violet, which is brighter than the Web color indigo but not as bright as electric indigo.

Electric indigo may be used as a glow color in computer graphics lighting. It is said to change color from indigo to lavender when blended with white.