Another key element to high-throughput testing is the development and validation of proxy measurement techniques. We posit that the many physically-and chemically-meaningful signals have optical signatures that are often overlooked. Here, we use a visible-light camera as a proxy for perovskite phase transitions, validate this proxy using X-ray diffraction (XRD), and describe the limits under which this proxy measurement is valid. Using an optical proxy for stability accelerates the rate of data acquisition by more than an order of magnitude and enables low-cost in-situ measurements during environmental degradation.