Coloration changes in natural ruby induced by oxygen ion implants correlated with cathodoluminescence data

Abstract

Ruby is a mineral in the corundum (Al2O3) family and it is remarkably valuable as a gemstone. From the physics point of view, the ruby coloration depends on the balance of trace or chromophore impurities and defect complexes in the Al2O3 lattice. Shifting this balance into right direction is of paramount importance for the ruby value as the gemstone and ion implantation can be applied for this purpose. Thus, in the present study, we explored the influence of high dose oxygen ion implants on the natural ruby coloration. By performing quantitative colorimetry analysis, we detected prominent coloration changes unambiguously attributed to the effect of the implants, even though the implanted oxygen profile was located at the near surface region of the sample. Moreover, applying near surface sensitive cathodoluminescence measurements we observed spectacular changes in the spectra correlated with the implants. Importantly, the trends observed in the colorimetry and cathodoluminescence as a function of the implantation parameters were consistent. As such, the present paper provides both the scientific perspective and quantitative interpretations potentially paving the way for the ion beams applications in the gemstone industry.