Milton--I agree that it's tapered at the bottom, but the reason I posted the pictures I did was because I liked everything about that ring. For example, in the Gavin setting, I don't like the mount (I actually haven't liked any mount I've seen, including cathedral mounts, save for the one in my picture). I did try to have it custom built, but I got burned terribly--the setting ended up looking nothing like my pictures, nor what I saw in person.
I'm sorry I don't have any more information, but I really do appreciate everyone's help thus far.
I'm sorry I don't have any more information, but I really do appreciate everyone's help thus far.