Which optical phenomenon explains the brilliant sparkle of a cut diamond?

💡 Solution & Explanation

The brilliant sparkle of a cut diamond is caused by total internal reflection, which occurs because the critical angle for diamond and air is exceptionally low at about 24.4 degrees. Consequently, light entering the meticulously cut facets bounces repeatedly inside the gemstone before emerging through specific viewing faces, creating intense brilliance. While dispersion splits white light into its constituent rainbow colors, the overwhelming sparkle relies fundamentally on total internal reflection. Diamonds are also studied for possessing the highest thermal conductivity among natural bulk materials.