This specific 3D model, "Solitaire Engagement Ring 3D print model 77", is an asset made available by "Unknown author".
You can download this asset for free at "Unknown platform" by following the link.
The license for this digital asset is "Unknown license".
STL (Stereolithography, filesize: 2.57 MB), 3DM (Rhinoceros 3D, filesize: 2.06 MB)