Ultrasmall nanoparticles have seen growing interest in several fields such as medicine, optics, and catalysis due to their unique size-dependent properties. Among these are fluorescent core-shell silica nanoparticles synthesized in water known as Cornell prime dots (C’ dots), which are composed of a silica core and a poly(ethylene glycol) (PEG) shell. These C' dots are poised to become promising diagnostic and therapeutic tools in medicine, particularly for cancer applications. While spherical C’ dots have already been in FDA-approved human clinical trials, exploration has expanded into different topologies of silica nanoparticles such as rings and cages, providing higher aspect ratios and higher surface area to volume ratios. For clinical translation of such nanostructures, quantitative assessments of their size and size dispersity remain parameters for further investigation and are critical to understanding and evaluating their effectiveness and safety in nanomedicine applications. Here, solution small-angle X-ray scattering was employed to characterize 3D structural details of ring-type silica nanostructures and their size and size dispersity. A hollow cylinder model provided consistent structural and dispersity parameters that were supported by transmission electron microscopy investigations.