Question

Sparkling of diamond is because of

• A. total internal reflection
• B. refraction
• C. diffraction
• D. scattering

Answer 1

Answer: (A)

The brilliance of diamond is due to total internal reflection of light, $\mu$ for diamond is $2.42^{\circ }$ so that critical angle for diamond-air interface as calculated is $24.4^{\circ }$.
The diamond is cut suitably so that light entering the diamond from any face falls at an angle greater than $24.4^{\circ }$;
suffers multiple total internal reflection at the various faces, and remains with in the diamond. Hence, the diamond sparkles.