the color violet This is a file from the Wikimedia Commons.

the color purple This is a file from the Wikimedia Commons.

The optics of purple

Purple, unlike violet, is not one of the colors of the visible spectrum. It was not one of the colors of the rainbow identified by Isaac Newton, and it does not have its own wavelength of light. For this reason it is called a non-spectral color. It exists in culture and art, but not, in the same way that violet does, in optics. It is simply a combination, in various proportions, of two primary colors, red and blue.

— Wikipedia on Purple

2013.12.22 Sunday ACHK