Summary

This parametric Sphere Cutter script will allow you to easily create jewelry accessoriers. You can create rings and bracelets from a sphere basic shape.
Gem inserts are available.

The idea of cutting spheres for rings is similar to "Ring a Thing" http://www.thingiverse.com/thing:13902

Instructions

Open the script with OpenScad. Set your parameters and check the result.

There are 3 different styles for cutting the side walls of the sphere.
You can cut sidewalls with another sphere (ctyps) or a flat plain (ctypf).
The cutting position is determined by two x-values, the upper (x1, fx1) and lower (x2,fx2) half of object's thickness.
The third method is the central cone (ctypu) which is defined by a distance from the center of the object (ux) and the half of cone's angle (ualpha).

Examples:
sp2ri_01.stl = sphere ring with a gem insert (green gem)
sp2ri_02.stl = bracelet
sp2ri_03.stl = flat ring with a gem insert (white gem)

I am still trying to find the best way for gluing the gems.
i glued the white gem by melting the PLA with a hot knife.
Then i used universal glue for the green gem. But still thats not the best way.
Maybe gluing in general is not the best way.

Sphere2Ring Script