I haven’t done a mini-tut in awhile ...and i’d been planning on doing this tut for a few years ...and other stuff isn’t ready to post yet, so .....

i refer to this colour scheme (gamut, etc) as “tourmaline” as it resembles the colours usually associated with those crystals. You can find thousands of pictures in this colour scheme here on FA and on dA - it's a popular colour scheme (i just posted some examples in my faves that were all up-loaded in the last few days - going to post some all time faves of this colour scheme as well) .

The obvious thing is that red and yellow are out.
Not so obvious is that saturation of the colours have to be kept somewhat low as at higher saturation it starts to look like the black-light/rave colour scheme or one of the blue-purplre colour schemes. The saturation can be somewhat higher than what's shown here, and also darker or pastel.
Black, white and greys work fine without disrupting the effect - sometimes even enhancing it.
Any of the colours can dominate, and any of the colours could be used as accents.
It can be peaceful, dreamy, evening, nature, and even spooky in mood depending on the subject.

So there it is, a short tut. i'll be doing some more like this on the orange-and-green colour scheme, pink-and-green, blue-and-purple, etc.
(The colour chart in the middle here is cut out from a chart i made for myself about a decade ago of 10,080 colours etc etc)

Examples were made in Krita.

No actual art was harmed in making this mini-tut.