What is brilliance in a diamond?
By Jared James · Last updated 21 May 2026
Definition
Brilliance is the white light that returns from inside a diamond or other transparent gemstone to the observer's eye, creating that characteristic bright, mirror-like glow. It is distinct from fire, which is the coloured flash caused by light splitting into its spectrum, and from scintillation, which is the sparkle you see as the stone moves. A well-cut diamond is optimised for brilliance by ensuring light that enters through the crown bounces between the pavilion facets and exits back through the top rather than leaking out through the sides or bottom.
Frequently asked questions
- What is the difference between brilliance, fire and scintillation?
- Brilliance is the white reflected light that makes a diamond bright, fire is the coloured flashes of dispersed light you see as the stone is tilted, and scintillation is the pattern of light and shadow, the sparkle, when the stone or the observer moves. All three together make a diamond look alive.
- How does cut affect a diamond's brilliance?
- Cut is the biggest factor. When a diamond's proportions are correct, light that enters through the table reflects off the pavilion facets at the right angles and returns upward through the crown. Shallow or deep cuts let light escape through the sides or bottom, dulling the stone.
- Do all gemstones show brilliance?
- All transparent gemstones reflect internal light to some degree, but diamonds are particularly prized for their brilliance because their very high refractive index bends light sharply, keeping it inside the stone for longer before releasing it. Some gems like moissanite show even higher brilliance.
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