No - unscratch that!
We are using a range of colour spaces including CIEL*a*b* to generate the base palette. Then CIELAB Delta E* to maximise the distance between all the colours. It’s all about perception!! The base palette is then manipulated to create the variations per block as show the in screenshot. Then the World Builder has another structure that procedurally selects from the palettes to colour a new world. There is a degree of discretisation in the result but our tests show it’s not noticeable. Each world can generate it’s own set of block colours. This means that we can dramatically vary the visual theme and result, still allow block transitions between worlds, universally name colours, and (in the future) colour transmogrification between block types.
(Never thought I’d get to use that word in a post!)