I've always pictured the wedges as bright green, barely translucent, though in my mind they're also much closer to the ship than the rendition in the wiki. But as I was thinking of how a TV adaptation might mangle/bungle this, I don't think the books ever say that the wedges are visible in the EM spectrum at all. What we do know is that they:
- are very bright sources in gravitic sensors (which propagate FTL);
- cannot be seen through from the outside;
- their distortion can be compensated by the ship inside;
- Ghost Rider RDs are pretty stealthy
Given the last, I actually think now that the wedges might actually be dark, or at worst a hazy very dark grey, like an unfocused lens spreading the light of the stars.
So what colour have you always imagined the wedges to be when you read the books? And what do you intellectually think they ought to look like?
Follow-up question: how do you think a TV adaptation should show them?