Nanoparticle suspensions are known to offer a variety of benefits for thermal transport and energy conversion. Of particular relevance here are the vast changes to the radiative properties due to the plasmonic nanostructures' large extinction cross section at the corresponding surface plasmon resonance (SPR) wavelength. Recent papers have showed that dielectric core/metallic shell nanoparticles yielded a plasmon resonance wavelength tunable from visible to infrared by changing the ratio of core radius to the total radius. Therefore, we are interested in developing a dispersion of core-shell multifunctional nanoparticles capable of dynamically changing their volume ratio and thus their spectral radiative properties. This paper investigates the surface plasmon resonance effect, wavelength tuning ranges for different metallic shell nanoparticles, and explores the solar-weighted efficiencies of corresponding core-shell nanoparticle suspensions. Through our electrostatic model, we estimate a red-shift in the plasmon resonance peak from a wavelength of about 600 nm to around 1400 nm for Au coated silicon core nanoparticles. Using core-shell nanoparticle dispersions, it is possible to create efficient spectral solar absorption fluids and design materials for applications which require variable spectral absorption or scattering.