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

Refractive index of diamond is about 2.42, much larger than that of ordinary glass. The critical angle for diamond is above `24^(@)`, much less than that of glass. A skilled diamond cutter 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.