You asked about how to prevent a top-heavy ring from spinning on the
finger. Do remember that as the band’s width increases, the size
needed will have to increase as well. Keeping the same width as your
20mm wide stone for the entire ring band will make it very wide.
That width alone would make the ring less likely to spin. if it was
comfortable to wear.
You could taper the shank from the width under the stone, to the
back. think signet ring style. The band design does not ‘have’ to be
circular - it could be slightly triangular, with the stone mounted
on one corner and the back of the band being the flat side opposite
the point. OR, simply make the back of the band flatter, and the
rest of the band shaped over the finger.
The rest of the Orchid community will likely have better
suggestions, and I look forward to those responses. Let us know how
you decide to design the ring.
Judy in Kansas, where the evening temps were down in the 50s!! High
for today is to only make the 70s. WOW. Great gardening opportunity
with little sweat.