The Science of Scintillation™ | Diamond Grading
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The Science of Scintillation™

Scintillation Metrics and Maps
Scintillation is sparkle. Scintillation is the play of white and colored flashes of light seen when the diamond is viewed in motion.  Viewable with the naked eye, scintillation is the life of the diamond.

The two dynamic aspects of sparkle are called flash scintillation and fire scintillation.

In 2007, the research team at AGS Laboratories published a landmark paper detailing their findings on diamond cut. This paper was the first of its kind to be published in a major optical sciences journal and was also one of the first major articles to discuss The Science of Scintillation™:

“In the presence of brilliance and fire the most appealing effect is gem scintillation. In this effect the fire pattern changes dynamically and flashes of white light are perceived across the crown of the stone. Thus there are two major scintillation effects, fire and flash scintillation. To observe them it is required that the stone, the observer, or the illumination conditions be in movement.”
"Evaluation of Brilliance, Fire and Scintillation in Round Brilliant Gemstones” Optical Engineering (2007)


This research serves as both the foundation and inspiration behind the scintillation metrics and maps.


Light and Movement

Without light, diamonds can’t sparkle.  As light is a key ingredient, diamonds with the highest potential for sparkle find light in the broadest ranges of commonly encountered illumination environments and redirect the light to the observer’s eye. 

The other key attribute is movement, which sets the scintillation performance apart from its light performance.  A motionless diamond in broad diffuse lighting cannot demonstrate the beautiful display of scintillation. It is movement that causes the flickering of sparkle across a diamond, whether it is the diamond, the observer, or the light source that moves.


Diamond Flash Flash

Flash scintillation is the dynamic pattern of white sparkles observed across a diamond’s crown. Because flash can be seen across a broader range of light environments, it is more common to see white sparkles in a diamond than colored flashes of fire.
Diamond Fire  Fire

Fire scintillation is the dynamic pattern of colored sparkles observed across a diamond’s crown. Because of the refraction caused by a diamond’s faceting, normal white light can be split into many spectral colors as it leaves the diamond.


Metrics and Maps

The main principle behind the AGS Laboratories’ scintillation analysis is that only diamonds exhibiting the highest scintillation potential should receive the best “sparkle” score.  A key characteristic of a diamond with very high scintillation potential is the sparkle seen across the full crown of the stone. A poorly cut stone could have “dead” or underperforming areas in the table, bezels or stars, where no flash or fire is seen.

According to the AGS Laboratories’ scintillation metrics, diamonds that score a 0-0 have attained the highest possible grade for both flash scintillation and fire scintillation. These stones exhibit the white and colored sparkles across their full crown, “finding light” over a broad range of movement, with minimal underperforming areas. 

The value of scintillation maps is they compress the dynamic display of a diamond in motion into a single static image for use in a report.  A 3-D model of the diamond is ray traced over a series of orientations to create an array of data and a series of color-coded maps.  These snapshots of data are then averaged and overlaid to create a cumulative color-coded map demonstrating important factors such as facet size, flash potential and dispersion.
Flash Scintillation Map Flash Scintillation Map

This map demonstrates flash scintillation—white sparkles. The white areas show where flash is most likely to be seen, while the dark areas show where flash is least likely to be seen.
Fire Scintillation Map  Fire Scintillation Map

This map demonstrates fire scintillation—colored sparkles. The lighter areas show where fire is most likely to be seen, while the darker areas show where fire is least likely to be seen.
Scintillation Patterning Map  Scintillation Patterning Map

This map demonstrates the pattern and relative size of the diamond’s sparkle, whether flash or fire scintillation. The lighter areas show where the largest sparkles should be seen, and the darker areas correspond to the smaller sparkles.

Mission Statement

The American Gem Society (AGS) is a nonprofit trade association of fine jewelry professionals dedicated to setting, maintaining and promoting the highest standards of ethical conduct and professional behavior through education, accreditation, recertification of its membership, gemological standards, and gemological research.

The Society is committed to providing educational products to inform and protect the consumer and to contributing to the betterment of the trade by creating industry standards to protect the jewelry-buying public and the fine jewelry industry as a whole.

AGS Laboratories, founded to support the AGS mission, is a nonprofit diamond grading laboratory with a mission of consumer protection. Adhering to the AGS Diamond Grading Standards, AGS Laboratories is dedicated to offering diamond grading reports that provide consistency and accuracy based on science.

American Gem Society