What is the reason for the diamond sparkle?
Diamond sparkles because of total internal reflection.
Total internal reflection: The phenomenon which occurs when the light rays travel from a more optically denser medium to a less optically denser medium.
They are two conditions of total internal reflection:
Along with total internal reflection, the following are the three other factors that determine the sparkling of the diamond:
Reflection: When a ray of light approaches a smooth polished surface and the light ray bounces back, it is called the reflection of light.
In diamonds, reflection occurs when the light ray hits the diamond and bounces back, giving away an instantaneous shine. Reflection is the light that hits the diamond and is immediately bounced back up, giving it an instantaneous shine.
Refraction: Refraction is the bending of a wave when it passes from one medium to another. The bending is caused due to the differences in density between the two substances.
Dispersion: When white light is passed through a glass prism it splits into its spectrum of colors (in order violet, indigo, blue, green, yellow, orange, and red) and this process of white light splitting into its constituent colors is termed as dispersion.
In diamond, as the light moves through the diamond, it is scattered and fractured, creating the sparkle that diamonds are known for. This is the refraction. Refraction and dispersion are the reasons why the light ray travels through the diamond. Diamond acts like a tiny complicated prism through which the light ray travels at different angles and gives a shiny appearance.