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Abstract The variability of red hues in tourmaline is primarily governed by the presence and oxidation state of Mn and/or Fe. The present study explores the atomic-scale mechanisms responsible for color changes in Mn-bearing elbaite (achroite variety) from the Rosina pegmatite (Elba Island, Italy) following sequential electron irradiation and heat treatment. Initially colorless, the elbaite sample developed a pinkish-red color upon electron beam irradiation, attributed to the oxidation of Mn2+ to Mn3+, as confirmed by optical absorption spectroscopy analysis. Subsequent heating at 500 °C in air reversed the color change, restoring the sample to its original colorless state. This reversal corresponded to the disappearance of the Mn3+ absorption band at ∼19,000 cm⁻1 and the recovery of the initial optical spectrum. Fourier-transform infrared spectroscopy showed that Mn oxidation occurred without deprotonation of the (OH) group, as indicated by the persistence of the ∼3662 cm⁻1 (OH)-band. Electron paramagnetic resonance data further revealed that the electron ejected during Mn2+ oxidation was transiently trapped on a newly formed H0 species at the expense of the (OH) in the crystal structure and subsequently recaptured during the thermal reduction process. This evidence supports a reversible, charge-coupled mechanism in which Mn redox transitions are driven by irradiation and heating, with the (OH) acting as an electron trap that modulates color expression. At higher temperatures, however, the behavior changes again. Heating experiments above 700 °C promote irreversible Mn2+ oxidation to Mn3+, accompanied by deprotonation and resulting in intensified red coloration. These processes can be described by the following reactions: (i) electron irradiation, Mn2+ → Mn3+ + e−; (ii) heating at 500 °C, Mn3+ + e− → Mn2+; (iii) heating at 750 °C, Mn2+ + (OH)– → Mn3+ + O2− + ½H2(g). In (i) and (ii), the electrons are involved in the redox process in which (OH)– = O2− and H0, representing the reversible transfer between hydroxide and the O2−…H0 intermediate. These findings provide new insights into the redox-driven chromatic behavior of tourmaline and highlight the relevance of these mechanisms for understanding natural color variations and for refining heat-treatment strategies in gemological applications. The identification of this charge-coupled process goes beyond mineralogical and gemological relevance. It in fact provides a framework for interpreting how hydrous minerals may respond to radiation and thermal fluctuations in geological and planetary environments, where proton-electron interactions influence color development, defect formation, and redox stability.