Diamond fin rings

I've struggled to find a name for these rings and the collection of jewellery to which they belong.
The gold terminals look a little like the cross section
of a fin (something mechanical rather than a fish's fin) and so I settled on that.
(Other ideas entertained gladly!)
The shanks are 3mm or 3.5mm reversed D sections and the diamonds are 1pt in the
slimmer design and 1.5 in the heavier.