Comment by d1sxeyes

That’s a bit complicated. The difference between синий and голубой is not really a difference in hue, it’s a difference in brightness.

It tends to be true that hues tending towards green are perceived more brightly than hues tending towards red, which means that blues with more green in them are more likely to be голубой, but by virtue of the fact they are perceived to be brighter.

But in principle, the line is drawn horizontally on the colour chart (or at least diagonally), not vertically.