Described herein are glass ceramic compositions with bulk scattering properties that have improved light extraction properties due to high levels of diffuse transmission, and methods of making such glass ceramic compositions. The compositions are based on Li2O—Al2O3—SiO2 glass ceramics and with the proper crystal size, exhibit good volume scattering characteristic for visible light and enhance the outcoupling from the substrate to the air in optical devices, such as light emitting diodes.