Hi Brian, have a look here, this could be the ‘seven colours’ mentioned. Here is the link.
http://www.colorsystem.com/projekte/engl/66isle.htm
'In the Islamic tradition, colour is primarily seen from a metaphysical viewpoint which allows the duality of light and shadow to be recognised as the continuous possibility pervading the universe. The number seven dominates the traditional palette of colours, which are arranged in groups of three and four, with the two systems being linked. One order is based on the three colours black, white and sandlewood (related to the colour of the earth), while the other is centred on the four colours red, yellow green and blue.'