This model created in Zbrush and has a polygonal geometry :
Model geometry is mesh(polygonal),this is not a Rhinoceros Nurbs geometry,its just imported into rhino 3dm file:
Sl file is cleaned in Materalise Magics (22-version) and ready for ptinting
Volume = 1330.22846 (+/- 1e-06) cubic millimeters
Ring size -20mm :(USA-10.25)
Metal weights: Gold 14ky-17 grams Gold 18ky-20.5 grams Silver 925-14 grams