Fig. 1. Color appearance of three blue spinels under different light sources
From top to bottom, this is CS-1, BS-1 and BS-2, D65 light source on the left and A light source on the right

Fig. 2. UV-Vis spectrum of sample color change spinel (CS-1)

Fig. 3. UV-Vis spectrum of sample BS-1 and BS-2

Fig. 4. Raman spectrum test results of three spinel samples (λ=532 nm)

Fig. 5. PL spectrum test results of discolored spinel (λ=532 nm)