e) The refractive index of diamond is much greater than that of ordinary glass. Is this fact of some use to a diamond cutter ?

Explanation

(e) Refractive index of a diamond is about 2.42, much larger than that of ordinary glass (about 1.5). The critical angle of diamond is about `24^(@)`, much less than that of glass. A skilled diamondcutter exploits the larger range of angles of incidence (in the diamond), `24^(@)" to "90^(@)`, to ensure that light entering the diamond is totally reflected from many faces before getting out–thus producing a sparkling effect.