Diamond Sparkle - The Secrets of Scintillation

As soon as the first rudimentary facets were put on a diamond crystal, mankind became aware of the primary attribute that makes diamonds beautiful. They sparkle! And it can be an absolutely mesmerizing effect. But it was not until relatively recently that we have begun to understand what actually makes a diamond sparkle. And we have the AGS (American Gem Society) Laboratories to thank for it. Their advanced research has greatly “illuminated” the subject of diamond brilliance, dispersion (fire) and scintillation (sparkle).

In 2007 the AGS published the results of their landmark study on diamond light performance including important findings related to scintillation. This ground breaking research was published in the Journal of Optical Engineering and represents the foundation of the only scientifically rigorous, peer reviewed, and academically vetted light performance based cut grading system in the world. As a result of the pioneering work done by the AGSL in this critical area of diamond grading, astute consumers shopping for diamonds with proven light performance at the top of the scale look for certified diamonds with AGS Triple Zero reports.

Diamond light performance is determined by a complex interaction of light with every facet of the diamond and with the observer.  The design and craftsmanship of the diamond therefore has the greatest impact on light performance, and diamond sparkle is determined by the cut quality of the diamond. The GIA (Gemological Institute of America) highlights this fact as well with the following simple and unambiguous statement on their website: “The allure of a particular diamond depends more on cut than anything else.”

In order for a diamond to refract and reflect light beams and return them to the eye in a way that creates these beautiful optical effects, many things are required. The diamond must have proper proportions, facet alignment and polish. Light must be able to enter the diamond from a wide range of angles, be internally reflected, and then returned to the eye with minimal light leakage in the process. 

Scintillation is a product of motion. It requires movement of the diamond, the light source, or the eye of observer in order to produce sparkle.  A key component is dynamic contrast within the diamond which creates a blinking, on/off effect among the facets. And the contrast must be present in the right amount and distribution for the effects to be positive. Too much contrast and the diamond can appear overly dark, too little and sparkle is diminished.

The AGS research has revealed that diamond scintillation is actually a product of two separate factors – flash scintillation and fire scintillation. Flash scintillation is seen in sparkles of white light. Fire scintillation is seen as sparkles of color that are the product of the bending of light as it is separated or “dispersed” into its spectral components. Because flash can be seen across a broader range of light environments, white sparkles are more commonly seen.

In addition to the proportioning and alignment of the facets, another critical aspect of scintillation is facet size. Or more precisely, “virtual facet” size. The AGS research demonstrates how a given facet arrangement produces multiple reflections from individual facets. As with contrast, virtual facets must be present in a proper mix of sizes in order to produce the most beautiful diamond sparkle. This understanding of “patterning” helps to explain the somewhat counterintuitive observation that simply putting more facets on diamond does not necessarily lead to more attractive sparkle.

The AGS system involves direct assessment of a model of the diamond generated by the accurate measurement of every facet on the diamond in a full three dimensional view. Scintillation “maps” are created from sophisticated ray tracing technology that can identify the areas in the diamond where scintillation can occur. There is a separate map for Flash, Fire and for Patterning. Analysis of these three maps provides the basis for the new AGS Scintillation Report that for the first time succeeds in accurately quantifying diamond sparkle.

Cutting the most beautiful diamonds in the world requires tremendous skill, extra time, and the sacrifice of additional carat weight. Taking diamond craftsmanship to the highest level naturally results in higher cost. It involves the best facet design- diamonds cut to ideal proportions. It involves a philosophical determination to cut for beauty at the expense of carat weight. And it requires the most skilled craftsmen using state of the art equipment. The A CUT ABOVE® Super Ideal is such a diamond. It is a diamond cut for extreme precision and uncompromising beauty. The benefits of owning such an extraordinary diamond are experienced every day with every glance of every eye.