“I paint ( I’m a watercolorist and also know about pigments ), so I’m very atuned to colors, shades, and variations of colors. Violet is a shade of PURPLE ( there are many different shades of all colors! )”
I don’t think you know what a shade is ...
Of course I know full well what a "shade" is. And it's NOT something attached to a window frame to keep out the light, in this instance!
Would you have preferred that I say "value" ( which is another word/term artists use to describe a color ) instead? Or how about talking paint consistency, i.e. like heavy cream,milk, or 2% milk, when talking about how much water one uses re watercolor.
"Shade" is also used when talking about many other kinds of things besides paint as well.
If a paint color is known by gamboge, for sake of argument, that's a SHADE of YELLOW, but it's quite different from one called aureoline and both are different from lemon yellow, but they're ALL a SHADE OF YELLOW!
Some paints are considered to be "warm" and some "cool", yet they can all be the in the same "family".
And THAT can be said of just about every single single color you can name, including VIOLET.