Lava worlds are rocky exoplanets that can provide crucial insights, not only into the composition of rocky exoplanets circling other stars but also into Early Earth evolution. These lava worlds are characterized by high equilibrium temperatures (>1500 K) that can maintain a (partially) molten state surface and are, therefore, key objects to understanding the underlying geological processes characterizing the first moments of a planet's history. The unique high-temperature environment of lava worlds offers an opportunity for direct observations of their surface emission and exploration of their composition within the capabilities of the James Webb Space Telescope (JWST). However, no reference library of the radiative properties of diverse (partially) molten surface materials exists yet, but it is critical to interpret observations. We are establishing such a reference library with the first laboratory in situ InfraRed emissivity measurements that determine the radiative properties of solid and molten Earth analogs (from Basalt to Rhyolite with tholeiitic characteristics) up to 2000 K. First, we discuss the importance of InfraRed high-temperature emissivity measurements and their applicability to lava world observation, and describe the relations between radiative properties, temperature, composition, and wavelength. Next, we model the photometric planet-to-star fluxes with these potential bulk compositions, to better reflect the magmatic processes occurring on a given exoplanet. Linking the interpretation of InfraRed spectra of possible lava world composition to JWST observation will offer clues about the composition and formation of rocky planets (e.g., Earth) in tight orbits around their host stars. Understanding lava worlds spectra using our database will enable us to refine our understanding of planetary diversity and the factors influencing the habitability of other worlds in our galaxy.