Purple

Purple (also called buni or soosani) is the general name for the color produced by the mixture of red and blue. The closest English term is "purple"; the Arabic equivalent is "أرجواني". This color cannot be obtained directly from a rainbow with a single wavelength; it arises when the eye and brain combine short wavelengths (blue/violet) and long wavelengths (red).

For this reason, in physics purple is described as a "non-spectral" color: it has no single light wavelength corresponding to it. The violet color at the short end of the visible light spectrum differs from purple, even though the human eye perceives them as similar.

How it is made

In the additive light color model (RGB), purple is obtained by mixing red light and blue light while keeping green low. In the subtractive model used in printing (CMY/CMYK), magenta and cyan dyes are mixed to produce a shade of purple. The distinction between purple, magenta, and violet is largely a matter of convention and depends on the system used to define it.

Historical dye

Purple dye of high repute was extracted from a shellfish found in the Mediterranean Sea; it was famous under the name of the Turkish dye (or Phoenician dye). Producing the dye required a large number of shellfish per kilogram of dye, which raised its cost. As a result, purple cloth was generally restricted to royalty and high officials, and some states by law limited who could wear it.

In the nineteenth century, chemical dyes derived from tar (aniline) began to be produced in factories, making purple an affordable color available to the general population. This change reduced the strict association between the color and social status.

Social meaning and use

Purple is associated with high authority, religion, and the customs of various groups. It is also used in the symbols of political movements and social campaigns. Naturally, plants such as lavender and violet, and fruits such as dark grapes, are among the sources of this color in nature.