Way back before the height cut debacle the diagrid was supposed to be lit red, but that was presumably value engineered out a long time ago.
" “The building changes shape as it ascends, it moves around. The shape,” he says, holding up his hand, “is like this, three fingers pointing into the sky.” Nouvel runs through a presentation on his laptop, showing proposals for the night-time lighting of the building (“it will make it look like it has blood running through the veins of the structure,” he grins) , the extraordinary interiors (“the structure becomes the space, we don’t need interior decorators here,” he grins again) and renderings of the pool and the gallery."
Source: Subscribe to read | Financial Times (subscription needed unfortunately)