Colour vision is a physiological phenomenon, and rays are not coloured (Newton, Wright). While counting hues of solar spectrum is a solved problem, the exact number of colours is unknown. Existing colour systems do not provide automatically colour census methods. This work addressed only to the 24 bit RGB-colour system. This complete colour space itself is countable. Discovering principles for ordering colours is a prerequisite of any efficient census algorithm. Colours (r, g, b) we define, as a partition of total n = r + g + b amount of intensity into 3 parts also with r/g and g/b ratios fixed. Partition spectra are the lexicographically sorted list of these partitions. Such and also geometrically defined sub-domains of RGB-cube can be transformed into 1D colour spectra by reshuffling according to their HSV-hue-angles in order to bring similar colours into close neighbourhood. These we call pseudo-solar colour spectra. Our estimation for subjectively discriminated RGB-colours is no more than 200000.