Brilliance, fire and scintillation are the three words most often used to describe how a diamond returns light. In everyday speech, brilliance is the white light you see in the stone, fire is the coloured flashes, and scintillation is the sparkle and the pattern of light and dark as the diamond moves. The Gemological Institute of America uses the word brightness for that white light return, and treats all three as part of a diamond's face up appearance.
Brightness, or what many people call brilliance
On its diamond cut pages, GIA defines brightness as the total internal and external reflection of white light. Some older and more general GIA writing still uses the word brilliance for the same idea. We use both terms in conversation, and we are clear that we mean the white light coming back from the stone, not a marketing score.
How much white light you see depends on the cut, on the lighting, and on whether you are looking straight down at the table or from an angle. A well cut stone looks lively without a dull, dark centre. We would rather show you the diamond on a video consultation, in more than one light, than ask you to trust a single still photograph.
Fire
Fire is the dispersion of white light into the colours of the spectrum: the brief flashes of orange, yellow, blue or green that appear as the stone or the light moves. GIA treats fire as one of the three face up qualities in its cut grading system for the standard round brilliant. You often notice it more under a smaller, sharper light than under a broad, soft one, which is why a ring can look quieter in an office and more colourful by a window or a lamp.
A photograph can catch a single flash, as in the picture at the top of this page, but it cannot show how often those flashes appear as you move your hand. That moving view is the one we care about when we look at a stone with you.
Scintillation
GIA describes scintillation as the pattern of light and dark areas, and the sparkle when the diamond, the observer or the light source moves. In its cut research it splits that idea into sparkle, the flashes themselves, and pattern, the arrangement of bright and dark areas you see even when the stone is still. A balanced pattern helps a diamond look crisp. A heavy dark patch through the centre, or a washed out look with little contrast, is something we would talk through before you approve a stone.
How this sits with the cut grade
For a standard round brilliant, GIA's cut grade takes brightness, fire and scintillation into account, together with weight ratio, durability, polish and symmetry. Those appearance qualities are not listed as three separate scores on the report. The cut grade is the summary. GIA does not assign that same cut grade to most fancy shapes, so for an oval, a cushion or a pear we still look at the face up appearance ourselves. Our guide to why cut matters explains the grade in more detail.
Lighting is part of the story too. GIA notes that a diamond's appearance changes with the light around it, which is why we avoid judging a stone from one photograph taken under a single lamp. On a video consultation we can tilt the diamond, change the background light and talk through what you are seeing.
Nothing is made until you approve the design and the stone in writing. A 70 percent deposit is paid then, making time is 5 to 6 weeks, and the ring is UK hallmarked before insured, tracked FedEx delivery. If you would like to look at stones this way, get in touch or browse the diamonds we can source.
Frequently asked questions
What is the difference between brilliance, fire and scintillation?
In everyday speech, brilliance is the white light you see coming back from a diamond. GIA uses the word brightness for that white light return. Fire is the coloured flashes. Scintillation is the sparkle as the stone, the light or you move, together with the pattern of light and dark areas.
Does GIA grade brilliance, fire and scintillation separately?
For a standard round brilliant, GIA's cut grade takes brightness, fire and scintillation into account as part of the face up appearance, alongside design and craftsmanship. Those three qualities are not published as three separate grades on the report.
Why does the same diamond look different in different lights?
A diamond's appearance changes with the light around it. A stone that looks crisp in daylight can show more coloured fire under a small, sharp lamp, and less of both under a very soft, even light. We try to show stones in more than one kind of light on a video consultation.
Do these terms only apply to round diamonds?
Brightness, fire and scintillation describe how any polished diamond returns light. GIA's published cut grade, though, is for the standard round brilliant. For fancy shapes we still look carefully at the face up appearance with you, rather than relying on a cut grade that the report may not include.