What Makes a Diamond Sparkle?
A diamond’s sparkle is largely determined by cut: the way its proportions, facets, symmetry and polish interact with light.
Cut is often confused with shape, but they describe different things.
Round, oval, emerald, pear and radiant are shapes. Cut quality describes how successfully the stone itself has been proportioned and finished.
How a diamond works with light
Diamond sparkle is usually described through brightness, fire and scintillation.
Brightness is the white light returned from the diamond. Fire refers to flashes of color. Scintillation is the pattern of light, dark and flashes that appears as the diamond or the person wearing it moves.
The balance between them depends heavily on the way the diamond has been cut.
Why proportions matter
Every facet affects the path light takes through a diamond.
When the proportions work together, more light can return through the top of the stone. When they do not, light can escape in ways that leave areas looking darker or less lively.
This is why two diamonds with the same carat, color and clarity grades can still look noticeably different.
Cut is different for fancy shapes
Round brilliant diamonds have established overall cut-grading systems.
Fancy shapes such as ovals, emerald cuts, radiants and pears require a more individual assessment. Outline, symmetry, proportions, polish and overall visual performance all matter.
A grading report can provide useful information, but it cannot replace looking at the finished stone.
The GRWN standard
GRWN applies high standards to polish and symmetry, with Triple Excellent specifications for applicable round brilliant center stones and Double Excellent standards for qualifying fancy shapes, as outlined in GRWN’s diamond standards.
The goal is straightforward: a diamond should look bright, balanced and well proportioned in the finished piece.