Aluminum oxide doped with a small amount of chromium is known as "ruby" or "ruby solution" and can be used as a thermochromic material. The Pechini sol-gel process is applied to synthesize this advanced material. The crystal structure, chemical composition, and morphology of the synthesized materials are analyzed using X-ray diffraction, scanning electron microscopy coupled with energy-dispersive X-ray spectrometry, and Fourier transform infrared (FT-IR) spectroscopy. The color performance of the synthesized material is analyzed using UV-VIS spectrometry. Finally, the thermochromism exhibited by the pigment powders at high temperatures is investigated. The pigment exhibits exceptional thermochromic properties, transitioning from pink to gray in a temperature range of 25-600 degrees C. The change in color is reversible and is dependent on the temperature and chromium concentration; however, it is independent of the exposure time. This novel property of Cr-doped Al2O3 can be potentially employed in reversible thermochromic sensors that could be used not only for warning users of damage due to overheating when the environmental temperature exceeds certain limits, but also for detecting and monitoring the temperature of various devices, such as aeronautical engine components, hotplates, and furnaces.