The word “violet” references both a specific hue of light and a genus of flowering plants. Understanding what color a violet truly is requires separating the physical properties of light from the botanical reality of the flower. Physics defines the color as a pure spectral phenomenon, while botany reveals the complex, variable coloration of the Viola genus. This exploration clarifies the difference between a monochromatic color and the shade of a common garden bloom.
Defining the Spectral Color Violet
Violet is formally defined as a color existing at the shortest-wavelength end of the visible electromagnetic spectrum. This position places it beyond blue and immediately before the invisible ultraviolet light. Scientifically, violet light occupies a narrow band of wavelengths ranging approximately from 380 to 450 nanometers (nm). The light in this range is monochromatic, meaning it consists of a single wavelength or a very narrow band of wavelengths.
Isaac Newton established violet as one of the seven colors when he first dissected the spectrum of white light in 1672. Because of its short wavelength, violet light possesses the highest frequency and energy of all the colors humans can perceive. When white light passes through a prism, violet refracts the most, confirming its distinct physical identity as a pure color of light.
Violet Versus Purple
The terms “violet” and “purple” are often used interchangeably in common language, but they represent fundamentally different color phenomena in optics and color theory. Violet is a spectral color, meaning it appears in the rainbow and is composed of a single, continuous wavelength of light. Purple, conversely, is a non-spectral color that does not possess its own wavelength on the visible spectrum.
Purple is created when the human eye perceives a mixture of light from the red and blue ends of the spectrum simultaneously. This combination stimulates the eye’s long-wavelength (red) and short-wavelength (blue) cone cells, but bypasses the medium-wavelength (green) cones. Our brain interprets this specific pattern of stimulation as the color purple, an experience that cannot be generated by a single wavelength of light.
This distinction is why violet, when observed as it brightens, tends to appear more blue, a phenomenon known as the Bezold–Brücke shift. Purple, being a constructed color mixture, lacks this spectral behavior, often appearing more reddish. The linguistic confusion stems from historical usage, where the terms were broadly applied to various hues between red and blue.
The Color of the Flower
The Viola genus, which includes the common violet, pansies, and violas, is what gave the spectral color its name. However, the flowers themselves do not consistently match the precise spectral definition of violet light. The genus comprises over 500 species, and their petals display a wide array of pigments.
While many species, such as the Viola sororia or common blue violet, exhibit a color that is a blue-purple or deep blue, their hues are not monochromatic. The flowers’ pigmentation, which includes compounds like anthocyanins, produces colors that range from pure white and yellow to various shades of blue and purple. The name “violet” was assigned to the flower historically because the purple-blue shade was the most characteristic color found in the wild species.