in my opinion this is a kind of bezel setting technique adapted to
the countour of those particular stones, I mean burnishing or
hammering the metal around the stone, maybe more burnishing than
hammering I don’t think craftsmen around 1700’s could think about
stone-in-wax casting, but one never knows. The tiny stones at the
ends are set simply by a very rough kind of bead setting technique.
Notwithstanding the wear and tear the ring in the picture shows, that
piece does not look like a good example of craftmanship, even for
that time. I have seen jewellery pieces thal old and more, and
although the setting techniques used tend to be rather simple, the
goldsmithing and know-how those pieces showed was simply brilliant,
nothing to do with the afore mentioned ring.
Hope this helps, bye