The cause of diamond shine is

Correct option is D

The correct answer is (d) total internal reflection

Explanation:
• The brilliant shine or "sparkle" of a cut diamond is primarily due to the optical phenomenon of Total Internal Reflection.
• A diamond possesses a notoriously high refractive index (roughly 2.42), which consequently gives it a very small critical angle of about 24.4°.
• Once light successfully enters the diamond, it repeatedly strikes the internal cut faces at angles greater than this critical angle, getting trapped and reflecting internally before exiting out the top.

Information Booster:
• While total internal reflection traps the light, the related phenomenon of dispersion is responsible for separating the white light into spectral colors, causing "fire".
• The same optical principle operates in fiber-optic cables to transmit data over long distances without signal leakage.

Additional Knowledge:
size (Option a)
• The physical size or carat weight of the diamond heavily impacts its value but does not physically determine its optical brilliance.
cutting (Option b)
• While precise diamond cutting actively facilitates total internal reflection, the fundamental physical phenomenon causing the shine is the reflection itself.
reflection (Option c)
• Simple surface reflection only accounts for a fraction of the shine; it is the "total internal" bouncing that generates the iconic brilliance.
None of the above/More than one of the above (Option e)
• Incorrect, as total internal reflection is the definitive scientific answer.

So the correct answer is (d)