Violet is an uncommon word. It isn't found very often in English, and it isn't found in the Bible at all. So why, if it's part of the rainbow, isn't it used in the Bible, or, much, by us? Probably because there are other Bible words which may refer to violet. I plan to do a post on these later.
So what is violet? Let's put it this way. It's the color furthest from red in the rainbow--bluer than blue.
Voltaire wrote as follows:
Sir Isaac Newton has demonstrated to the eye, by the bare assistance of the prism, that light is a composition of coloured rays, which, being united, form white colour. A single ray is by him divided into seven, which all fall upon a piece of linen, or a sheet of white paper, in their order, one above the other, and at unequal distances. The first is red, the second orange, the third yellow, the fourth green, the fifth blue, the sixth indigo, the seventh a violet-purple. Each of these rays, transmitted afterwards by a hundred other prisms, will never change the colour it bears; in like manner, as gold, when completely purged from its dross, will never change afterwards in the crucible. - Voltaire, Letters on the English, Letter XVI.
So violet, like indigo, has a distinguished history as a color name. Newton used it. (I'm not suggesting that he invented these names, just that he used them, thus dignifying them as part of his study of optics. He pioneered that field, as well as the study of motion.)
There is a plant, or several plants, named violets. See here for the American Violet Society homepage, and here for The Violet Society's. A minor character in the comic strip Peanuts was named Violet.
Here's the Wikipedia article on violet. As of February 24, 2005, it is very short.
One good product of writing this series has been that it has made me think. One thing that hadn't occurred to me before is to ask why, if the color spectrum is part of a linear series, it can be thought of as a wheel? Violet is next to red on color wheels. That seems to be as if, in singing a scale, you went from middle C to high C , and, instead of on to high D, immediately back to the D above middle C. Why can colors be arranged in a circle? Here's an answer:
The sensation of violet caused by short-wavelength light appears somewhat purple, as if it contained long (red) wavelengths. The cause for this is that the long-wavelength ("red") receptors in the human retina are sensitive to the wavelengths in the violet region as well as the longer wavelengths in the red region of the spectrum. Violet is therefore perceived as a stimulus to both red and blue cones. - http://www.answers.com/topic/violet-color
Colors are part of a linear series, the electromagnetic spectrum. The next category, a little shorter in wavelength, a little higher in frequency, and with a little more energy than violet light, is ultraviolet. The Wikipedia article (previous link) on the subject says that some reptiles, birds, and insects can see ultraviolet. This means that their eye pigments aren't exactly the same as ours. Some objects in nature, including at least some birds and flowers, are partly colored ultraviolet. Our eyes just can't see them--some animals can. There are things that believers can see, figuratively speaking, that non-believers can't. There are things God can see that I can't. My eyes aren't made right.
Pigments absorb light. DNA absorbs ultraviolet, which means that DNA is absorbing energy. That means that DNA may be changed, or mutated, by exposure to ultraviolet light. Thus we can get skin cancers. Ultraviolet exposure also damages collagen, a protein found in skin (and elsewhere). Use sunblock.