I feel very badly for you. I had a similar experience when I moved my belongings via UPS from Portland, OR to Boston. I took my valuables with me when I flew, but then I checked my bags. My bags took a detour to LA and when they got to me, my most valuable possessions were missing. Then when my UPS boxes arrived, they were damaged and torn and there were things missing.
As far as UPS goes, I had a friend who worked at an oriental rug store (in Portland, OR). He said that when they shipped rugs, they would never state the full value because if they did, they would never get to their destination. But then again, the risk of under-insuring is self-evident. So the whole thing is a catch-22.
Your dags are certainly recognizable. If anyone had the nerve to post them on eBay I would see them and contact you.
I am sorry about your loss. I would be curious to know how the claims process goes; but having made a few dags I understand this is not just about the material value.