We present high signal-to-noise composite spectra of quasars over the redshift range 2.1 ≤ z ≤ 3.5, binned by luminosity, spectral index, and redshift, based on the DR12 BOSS quasar catalog. Selection effects and Malmquist bias have been mitigated for these spectra. As discussed in Jensen et al. (2016), these composite spectra indicate spectral evolution while holding luminosity and spectral index constant. Also included are the differential spectra composites of each parameter, including one derived from CIV FWHM (full width half maximum) binning, revealing a redshift evolution spectral signature similar to both the luminosity and CIV FWHM signatures. These composite spectra give way to interpret quasar diversity, and can be used to improve the templates used in redshift classification.