Diamonds are cut to take advantage of internal reflections of light. The angles of a diamond are cut so that all of the light that enters it reflects out the top. The light or brilliance that emerges from the top of a diamond is one of the qualities that determine its monetary value.
(a) What is the critical angle for light traveling from a diamond to air?
(b) Would diamond jewelers want to create angles smaller or larger than the critical angle?
(c) Zircon is an inexpensive substitute for diamond. Zircon’s index of refraction is 1.92. What is its critical angle?
(d) If a zircon has the same cut as a diamond, which will have a greater brilliance by internally reflecting more light to the top of the stone?