This specific 3D model, "Solitaire Engagement Art Deco Ring 3D print model 89", is an asset made available by "Unknown author".
Can be downloaded at "Unknown platform" by following the link.
The license for this digital asset is "Unknown license".
STL (Stereolithography, filesize: 28.8 MB), 3DM (Rhinoceros 3D, filesize: 19.3 MB)