Is it canon that the hemospectrum is just these 12 specific colours and if a troll has any value a bit different (saturation and stuff) it's a mutant? Like let's say this cerulean is the right one and somebody is cerulean but a bit different shade (is that the right word?) of it? If you catch my drift?

Seems to be that way, although there was a weird violet hue in one of the Friendsims, so who knows.