Minor Elements and Color Causing Role in Spinel: Multi-Analytical Approaches

Natural spinel (MgAl2O4) usually contains some minor and trace elements (e.g., Cr, Co, Fe, V) that may cause various hues. The ratios of these chromophores directly affect the color composition. red in is attributed to combination significant Cr V. Magenta purple blue green colors spinels are affected by Fe concentration, whereas orange shows contribution V content compared Fe. After heating experiment, advanced gemological investigation reveals noteworthy characteristic features. X-ray absorption spectroscopy (XAS) indicates a greater change oxidation state, as well disordering Broadening dominant peak at around 406 cm?1 with occurrences additional small peaks 715–719 Raman spectra, broadening 685 nm (R-line) poorly defined structure (N-lines) photoluminescence spectra should be indicators undergone heat treatment.