Warning: the image is pretty big. Probably bigger than it needed to be.
The grey areas are where the ground fabric seems to be consistently exposed. Much like the last pattern I posted, this could be due to caustic dyestuff eating away the threads, intentional picking out of thread (maybe it was gold!), left like that intentionally for a textured effect, or perhaps some other reason that I just can't think of yet. I have no data yet as to which reason is more likely.