Why Diamonds Sparkle: Physics of Refraction and Dispersion

Diamonds sparkle because they bend light strongly, thanks to their high refractive index.
When light enters a diamond, it slows down and bends sharply, bouncing around inside.
Total internal reflection traps light within the diamond, making it shine intensely.
Dispersion splits white light into rainbow colors, creating the diamond’s famous “fire.”
A well-cut diamond is shaped to maximize internal reflections and colorful flashes.
The brilliance depends not only on the stone but also on the precision of its cut.
Round brilliant cuts are designed with exact angles to enhance sparkle.
Other gemstones also refract and disperse light, but diamonds do it more dramatically.
Clean surfaces matter—dust or oil can dull a diamond by blocking light paths.
The mix of refraction, reflection, and dispersion is what makes diamonds dazzle uniquely.