10. The index of refraction of diamond is 2.42. Use the diagram below and knowledge of the phenomenon of total internal reflection (TIR) to explain why diamonds that are cut correctly are much more sparkly than a piece of glass of the same cut. What happens to incoming rays of light that is different from glass? Light entering through the top facet undergoes TIR a couple of times before finally exiting. Source: https://www.physicsclassroom.com/class/refrn/Lesson-3/The-Critical-Angle