With violet we come to the last hue in the visible spectrum, which is to say:


(Which was named for the colour of the flowers of Viola odorata.)

To me, violet is a shade of PURPLE. That is to say, "purple" is one of the basic colour words in English; and the word refers to a broad range of colours in the same way that BLUE, RED, YELLOW, and GREEN do—though PURPLE is not quite as basic a colour as those, being more on a par with ORANGE and TURQUOISE.

I would not, however, say that violet is focal PURPLE, i.e. the most perfect, ideal shade of PURPLE. That, to me, is a shade slightly more to the BLUE end of the spectrum:




Or, to put it another way, the perfect shade of PURPLE lies between indigo and violet: indigo is the colour transitional between PURPLE and BLUE; and violet lies at the far end of the spectrum. (Beyond that lies ultraviolet, which can't be seen by the human eye.)

BLUE	INDIGO	PURPLE	VIOLET

Of course, there's more to PURPLE than that. There are a lot of colours that are called "purple" but do not lie on the visible spectrum. They are the colours that are not in the paintbox—or, at least, not in any paintbox that I had as a small child. They are the colours that cannot be mixed—at least, not with any paints that I had back then. There are no rules for making them from RED, YELLOW, GREEN, BLUE, BLACK, and WHITE. They don't exist and can't be made—except, of course, that a lot of flowers come in these shades, so obviously they do and can.

To paraphrase Dr. Seuss's On Beyond Zebra, these are the colours that are on beyond the spectrum.

When people arrange colours in wheel form, these colours lie in a segment of the circle between violet and red. There's no common agreement on what the different shades should be called; and terms like "grape", "magenta", "orchid", "fuchsia", "lilac", "heliotrope", "plum", "puce", "pink", and "rose" get applied by different people to quite different shades. Nor do people agree on exactly how many distinct colours there are in this segment of the colour wheel, nor on how it should be divided up. It's a sort of Wild West for nomenclature.

Now, if you look at the Wikipedia article on violet, you will read this:

In optics, violet is a spectral color (referring to the color of different single wavelengths of light) and purple is the color of various combinations of red and blue (or violet) light,[5][6] some of which humans perceive as similar to violet. In common usage, both refer to colors that are between blue and red in hue, with violets closer to blue and purples closer to red.

If you compare this to what I have written above, you will realize that Wikipedia and I are saying exactly the opposite. To me, the heart of PURPLE lies between blue and violet; but according to the final sentence in the Wikipedia article, "purple" refers to the redder shades.

So what's going on?

At the beginning of the passage I've quoted, the article says, "[i]n optics". Optics is the branch of physics that studies the behaviour and properties of light. Scientists in this field identify "violet" as a light of any wavelength of 380 to 450 nanometers. It is a pure colour. However, colours of light can be mixed. That's how RGB computer monitors work. For example, yellow is a pure colour on the spectrum (570–590 nanometers in wavelength). However, the eye also sees a mixture of red and green light as yellow. That's how a computer monitor produces yellow colour on the screen.

In the same way, it is possible to mix red and blue light to produce a colour that the eye will interpret as violet. However, all mixtures of red and green light are perceived as equivalent to hues on the spectrum in the YELLOW range. Many mixtures of red and blue do not look like hues on the spectrum. That is why scientists working in Optics decided to use the name "purple" to refer to mixtures of blue and red—particularly for colours that are not on the spectrum, though I guess they also use "purple" for a mixture that simulates violet. (It's the fact that the colour is a mix of two wavelengths that matters as far as they're concerned.)

Well, all specialties have their jargon.

The problem here is that specialists tend to be the ones who write encyclopedia articles; and, when they are challenged by people unfamiliar with the jargon, they get defensive. They work so much in their field, and are so familiar with their own meanings for words, that they sometimes actually insist that the lay meaning is wrong, often with overtones of snootiness regarding the inaccuracy of "common usage". This is no doubt fascinating psychology; but it's irritating when you're looking a subject up, whether on Wikipedia or any other source.

Now, according to the Wikipedia article, in the "common usage", purple shades are redder than violet. I don't know what thumb they sucked this out of. Let's have a look at something that is genuinely aimed at the general public, specifically acrylic paint for handicrafts. Delta Ceramcoat makes a shade called "Purple" (for which the Americana substitute is "Dioxazine Purple"). On the right is a picture of a bottle of this Purple paint. It's definitely a shade bluer than the most violet hue of visible light. (So much for Wikipedia.)

In truth, there are a wide range of shades between violet and red; and the need for scientific jargon, printers' jargon, dyers' jargon, and artists' jargon—along with "common usage"—simply muddies the waters, for there is no consensus among any of them. Basically, every one of them has encountered the same problem, i.e. an inadequacy of colour terms; and each has tried, in their own way, to solve the problem—either by repurposing words that already exist, by borrowing new ones (from flowers, foreign languages, dyes, and the like), or by inventing words. And everyone does it differently.

How many perceptually distinct colours lie in this range? I don't mean the zillions of possible shades: I mean the sort of subdivisions I've been doing in my other posts.

Well, I count at least four:

VIOLET					RED

I could toss around terms like "magenta" and "fuchsia", and say that the leftmost looks like a shade of PURPLE and the rightmost pair like shades of PINK. (Think of all the different GREENs.) However, that doesn't deal with dark shades (think brown and olive), for which I would use terms like "plum", "puce", and "burgundy"; nor does it deal with the pastels (think peach and beige), which include "lilac", "heliotrope", "orchid", and (obviously) PINK.

Basically, though? I also lack words.