Diamond Scintillation and Why It Matters

April 24, 2023


Close your eyes and picture an ad for diamond jewelry. What does it look like? There’s probably a camera panning slowly over an elegant engagement ring or stunning diamond pendant. Every facet catches the light, drawing your eye to the stone’s seemingly endless sparkle. Flashes of white and rainbows keep coming as the camera turns. It’s the diamond at its very best, and it’s eye-catching from across the room.

That sparkling, flashing effect is mesmerizing. It draws everyone in and showcases why diamonds are as fascinating as they are beautiful. But what is that effect? Why is it so captivating? It’s called scintillation, and it’s one of a diamond’s most important (and gorgeous) components.

What is Diamond Scintillation?

In essence, diamond scintillation is a diamond’s sparkle. It’s the interplay of light, shadow, and motion inside the stone. It breathes life into the stone. There are two main types of scintillation, both accounting for different types of sparkle.

  • Fire Scintillation - Fire scintillation, like diamond fire, is all about color. It’s the colorful, rainbow sparkles in the diamond’s crown. White light enters the diamond and splits off, creating separate colors on the spectrum. With the right conditions, that shows up as diamond fire and fire scintillation.
  • Flash Scintillation - Flash scintillation is white sparkle. It is similar to brilliance, in that it’s focused on bright and white, and appears as white sparkles playing over the diamond’s crown.

Together, fire scintillation and flash scintillation create a diamond’s beloved sparkling effect.

What Factors Affect Diamond Scintillation?

Diamond scintillation can’t exist without two things: light and motion. The effect is lost with too little (or too much) of either, and scintillation requires a certain balance. If lights are too dim or overly diffused, there’s reduced potential for light play and, consequently, less sparkle and scintillation. Likewise, motionless diamonds don’t sparkle because the light isn’t moving. Both factors are necessary to achieve high levels of scintillation.

Cut is another major factor for scintillation. Well-cut diamonds allow in more light, which increases the amount of visible sparkle. Poorly cut diamonds lose a great deal of light through the bottom of the stone, which means there’s significantly less light play. That reduces scintillation, fire, and brilliance, so a good cut is incredibly important to the overall appearance.

Remember, because light and motion are both essential components of scintillation, anything that limits either of them will also limit sparkle. An improper cut, low clarity, poorly crafted settings, and just bad lighting all impact scintillation.

How Important is Diamond Scintillation in Diamond Grading?

As explained above, scintillation is closely tied to a diamond’s cut. Cut is one of the four major components of diamond grading. Scintillation, along with brilliance and fire, are the big appearance-based factors in grading a cut. There are only seven total factors, making scintillation quite important overall.

It’s likely that low-scintillation diamonds also have poor showings for fire and brilliance, which are all results of poor quality or craftsmanship. You won’t find an Excellent grade diamond with low scintillation.

How is Diamond Scintillation Measured?

Diamond grading, in general, is an intense and ever-evolving process. Scintillation is only one of many factors involved, just as it is only one aspect of grading the diamond’s cut. There are a few different ways to measure it, though.

  • Cylindrical Viewer - A diamond is viewed through a cylindrical viewer or colored dome, which gives a picture of how face-up light relates to or interacts with the way light enters the diamond. This can be used to evaluate scintillation, or potential for scintillation in a computer scintillation, but isn’t always used for that purpose.
  • Imaging Spectrophotometer - This method includes five images of the diamond. Each is taken at a different distance from the light source, then evaluated for the presence of fire, brilliance, and scintillation.
  • Human Perception - The human eye and human perception (and preference) aren’t very present in the other two methods. They are important, however, as people ultimately purchase diamonds. Scintillation heavily involves motion, light, and perception - the interaction between the three can’t be fully replicated by any type of machine or technology. There is some consensus about diamond scintillation, such as large dark areas being unappealing.

How Does Diamond Cut Affect Its Scintillation?

Cut is one of the biggest factors in scintillation. Why is that? Well, let’s look at what a diamond cut means.

Many people equate diamond cut with shape (pear, oval, heart, and so on), but that isn’t strictly true. Cut measures how well a diamond’s facets interact with light. It includes fire, brilliance, and scintillation, as well as physical aspects like girdle thickness, weight relative to diameter, polish, and facet symmetry.

How do those factors affect scintillation? If a diamond is too deep or, on the other hand, too shallow, it loses a great deal of light through the bottom of the stone. Less light means poor scintillation and sparkle.

Table size (another element of the diamond’s cut) affects scintillation, too. Small tables don’t let in enough light, making the stone appear dark and lifeless. Too-large tables prevent proper light dispersal, also reducing the amount of scintillation and sparkle.

Practically every aspect of a diamond’s cut has some effect on scintillation, as the cut determines how much light enters the stone and where it goes once it enters.

Final Thoughts

Scintillation is only one of many factors behind a diamond's appearance and grade, but it is one that most people notice first. The “sparkle factor” is what catches the eye and makes certain diamonds stand out more than others. It’s played up in presentations and advertisements for good reason. A lot of sparkle and a high degree of scintillation make a diamond unforgettable.

Of course, the most beautiful diamond is always the one you love most. All the measurements in the world can’t account for personal taste. Yadav Diamonds and Jewelry has a wide selection of diamond jewelry, engagement rings, and wedding rings. You’re sure to find the sparkling diamond of your dreams.

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