A large set of colour discrimination data based upon cathode ray tube (CRT) colours was accumulated and described in Part I of this article. The experiment was divided into 16 different phases according to different viewing parameters studied: sample size (large and small), background (mid-gray white, black, gray, red, yellow, green, and blue), frame (black and no frame), and width (no gap, I-pixel, 2-pixel, and large gap) and colour (mid-gray and black) of separations between pairs of samples. This part of the article investigates the changes of perceived colour differences caused by these variables. In addition, investigations were made to find the results from which phase agree best with results for surface colours.