We hypothesize that materials properties of interest such as electronic structure, composition, and defects have optical signatures, which can be rapidly measured and correlated with high-fidelity structural or electronic characterization methods. This is not a bidirectional relationship; while the presence of color change indicates some mechanism of material decomposition, the lack of color change does not imply stability. An optical proxy is thus a strong but noncomprehensive indication of material instability. This approach can be applied to perovskite degradation because halide perovskites like methylammonium lead iodide (MAPbI3) undergo phase transitions with distinct colors during degradation. By examining color change, we argue that it is possible to noninvasively monitor degradation kinetics in longitudinal perovskite testing.