Hey Injun,
re wefting, saw a few of what appeared to be grey wefts. as for the variation, there are several things that could account for this. The rug does not appear to have color run, but it is possible the black color dye could have been absorbed into the cotton during final washing.
If I'm not mistaken, the image of the whole carpet seems to have had contrast adjusted. If so, I don't know if this is to portray more accurate representation, but the colors do seem to be nice.
To answer the exact origin, again, Hamedan is about as far as I would go to attribute. There is a great book out there as netjim pointed out called
Oriental Carpet Design you may be able to ID with.
If you are interested in the use of Symbolism in carpet design (more for older tribal in particular) I can't recall the exact name, I think it's Stone's writing about Tribal Rug Design but I could be mistaken.
Seems like the design of your rug is pretty eclectic. I cannot necessarily point out all the designs and the symbolisms, I can tell you where I have seen some. The star with overlapping geometric figures I have seen in Caucasian rugs. The border reminds me of an old Karabagh design rug I have, although it does seem to have some resemblance to even war rug vehicles. The arrows in the border I have seen in Kourdish Rugs.
What I can tell you is there is a clear Herati design and mahi too. The Herati is the diamond like squares, the mahi refers to the sickle shaped like things diagonal. Mahi means fish - the older Persian rugs from the Safavid Period show this Fish shape much more clear.
I will continue on this if time permits, perhaps post an image to augment description.
Fun piece with very interesting border,
