When light passes through a diamond, several optical phenomena occur, making it a highly refractive and sparkling gemstone. Here's a general overview of what happens:
Refraction: The most prominent effect is refraction. Diamond has a high refractive index, which means that light slows down and changes direction when it enters the diamond from another medium, such as air. This bending of light is responsible for the brilliant sparkle and luster of diamonds.
Total Internal Reflection: If the angle of incidence is such that light tries to exit the diamond at an angle larger than a specific critical angle (approximately 24.4 degrees for diamond), total internal reflection occurs. This means that light reflects internally within the diamond, bouncing off the facets and surfaces, until it finds an exit point. This effect enhances the diamond's brilliance and allows light to travel long distances within the gem.
Dispersion: Diamonds exhibit dispersion, which is the separation of white light into its component colors. Due to the diamond's high refractive index, different wavelengths of light (colors) are refracted at different angles as they pass through the diamond. This results in the dispersion of light and the creation of a colorful play of spectral hues known as "fire."
Absorption: Diamonds also absorb some portions of the visible spectrum, particularly in the ultraviolet and infrared regions. This absorption affects the color appearance of the diamond. Pure, structurally perfect diamonds are colorless, but impurities or structural defects can introduce color.
Overall, these optical properties, including high refractive index, total internal reflection, dispersion, and absorption, contribute to the diamond's brilliance, fire, and the way it interacts with light, making it a highly sought-after gemstone.