Mathematical diagramming serves many purposes in mathematics research and education. It may be conceptual or representational in form, but in all cases, producing graphic presentations benefits from carefully considered use of the various elements of graphical composition. The challenge of mathematical diagramming – indeed, of all diagramming – is how to do it well, so that the diagram fulfills its specific conceptual and communicative purposes. This paper and workshop will examine how the considered use of colour in diagramming and in corresponding artefacts can identify and clarify mathematically pertinent features with respect to various mathematical insights. The idea and role of aesthetics in diagramming will be considered with respect to various representations and artefacts of interlacing and some of the related sensitivities, especially colour sensitivity, will be exercised. The reader should note that since the proceedings are printed in black and white, it is worth consulting the electronic version in the Bridges Archive to see the colour images.