Statement I: The colour of the gem stone 'ruby' is caused by the presence of $\mathrm{Cr}^{3+}$ ions

Question

Statement I: The colour of the gem stone 'ruby' is caused by the presence of $\mathrm{Cr}^{3+}$ ions in the octahedral sites of $\mathrm{Al}_{2} \mathrm{O}_{3}$\ Statement II: The colour in 'ruby' is due to interstitial defect.\

Professor PC Thomas Classes · Answer

This is due to d-d transition in the octahedral chromium (III) Complexex incorporated in alumina lattice\