This specific 3D model, "Oval Solitaire Ring 3D print model 21", is an asset made available by "Unknown author".
Can be downloaded at "Unknown platform" by following the link.
Usage of this 3d asset is subject to the "Unknown license" agreement.
STL (Stereolithography, filesize: 17.5 MB), 3DM (Rhinoceros 3D, filesize: 19 MB)