Achieving high optical transparency in thick polycrystalline materials requires stringent control over microstructural properties to reduce undesired scattering at the surface or within the ceramic. Significant scattering sources in polycrystalline materials include: (i) optical anisotropy between grains, (ii) impurities or secondary phases typically existing at grain boundaries, (iii) high surface roughness, and (iv) pores. In order to obtain high optical transparency, each scattering source must be reduced or eliminated. Throughout the remaining discussion, we will highlight how each scattering source is minimized and analyze the implication of microstructure on the ceramics' transparency. First, cubic symmetry eliminates scattering linked to optical anisotropy at grain boundaries. Second, single crystal source materials-as opposed to solution-processed or mechanochemically produced microcrystalline/nanocrystalline powders-are advantageous due to their higher purity and more perfect stoichiometry. Both minimize scattering linked to the presence of secondary phases or impurities in the final ceramic. The high chemical purity of prepressed powders is supported by XRD measurements (Figure ) and thermogravimetric analysis (Figure ), which show only perovskite linked Bragg reflections and mass loss consistent with only CH3NH3X and PbX2 decomposition. Figure outlines the processing guidelines employed to produce transparent MAPbX3 (X - =Br -, Cl -) ceramics. Millimeter to centimeter sized bulk MAPbX3 crystals were first grown via modified solvothermal methods (see SI for crystal growth and purification details). Then, two subsequent pulverization steps with a planetary ball mill followed solvothermal crystal growth.