Looking at the photos again, here’s a ring (click for a larger version):
… can anyone figure out who/what this is portraying?
Addendum (an hour or so later) … in addition to the comments attached to the photo itself, check out #169 on this page, which seems to be an identical ring or at least very close to it. According to the description there (which has a comparative scholarly citation), the image is of Minerva holding Victoria, with a shield behind her back. If it is the identical figure, one must wonder why someone supposedly involved in the Bar Kochba revolt would have a clearly pagan ring.
rogueclassicism 
No doubt the ring was owned by a Jew who killed a Roman officer and took his precious gold ring.