The first pic below was the day I got him. Still in his summer coat. The middle pic was about a month ago, now in winter fuzz (and dirt...!). In the the bottom pic he would almost pass for a bay, but I think it's just the light and the angle.
Now, here's what I've gone through in my mind: I doubt the bay coloring because while his lower legs are certainly mostly black, his mane and tail are not true black. So then I would switch gears to brown, but his head IS black!....there are no light-colored or brown hairs on his muzzle whatsoever. I don't have a good pic of his side right now, but there are sandy hairs around his flanks and hindquarters (you can actually see a hint of this in the first pic). AND, lately I've noticed that he has a distinct dorsal stripe, although I've ruled out dun because that is not supposed to exist in Arabians, unless he's not 100% pure Arab (he's not papered so I don't know for sure).
Again, this is more for my own satisfaction than anything else....But I'd love to hear what y'all think!