It commonly occurs that one person sees a particular colour chip B as saturated blue with no admixture of red or green (i.e., as “uniquely blue”), while another sees it as a somewhat greenish blue. Such a difference is often accompanied by agreement with respect to colour matching – the two persons may mostly agree when asked whether two chips are of the same colour, and this may be so across the whole range of colours. Asked whether B is the (...) same or different from other chips, they mostly agree – though they continue to disagree about whether B is uniquely blue. I shall argue that in such cases neither individual misperceives what colour B is. They differ, rather, in how they perceive the colour of B. (shrink)