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Diamond Scintillation: Guide To Diamond’s Light Performance

Diamond Scintillation: Guide To Diamond’s Light Performance

People often evaluate diamonds based on how much sparkle they provide. While choosing a diamond this way is perfectly fine, the diamond’s sparkle isn’t the only aspect of the diamond’s light performance – one of which is scintillation.

So, what is diamond scintillation?

Diamond scintillation refers to the flashes of light emitted from various facets towards the gem’s center as you move it.

But what are some other aspects of a diamond’s light performance? Are there things that can affect a diamond’s scintillation?

Answers to these – and many more – questions are covered in this article. So, let’s find out more about the diamond’s light performance, shall we?

What Is Diamond Brilliance?

Diamond brilliance is the white light you see from the stone and is basically the foundation of its beauty. 

Now, brilliance has two main components – contrast and brightness

Brighter diamonds return light ideally to the viewer’s eyes. Diamonds with shallow or deep cuts have less brightness since the light that enters the diamond leaks out of the stone.

However, for a diamond to be brilliant, it requires more than just brightness. It should also have a solid amount of light contrast. 

For instance, a sheet of plain white paper appears less vibrant than a chessboard, even though the latter has half of the light return of that piece of paper.

What Is Diamond Fire?

Diamond fire – also called dispersion – is the colored sparkle you can notice while observing a diamond when it’s exposed to light.

Diamonds with smaller tables and steeper crown angles tend to produce more fire because that combination also creates less light return. So, less light return makes it easier to notice colorful flashes of light that the diamond’s brilliance might otherwise outshine.

How Diamond Cut Impacts Brilliance, Fire And Scintialtion

The cut quality of a diamond can make or break its brilliance, fire, and scintillation.

Diamond’s facets, as you know, make up the stone’s surface. And when light hits the diamond’s surface, it enters it and bounces around – but where the light bounces depends on the gem’s cut quality of the diamond.

If a gemstone is cut in ideal proportions, it will bend and reflect light in such a manner that it will maximize brilliance, fire, and scintillation. On the other hand, the further away it is from the ideal proportions, the less brilliance, fire, and scintillation the gem will produce.

For instance, if the diamond is cut too shallow or too deep, the light would leak from the stone’s bottom section and won’t return to the viewer’s eyes. And as a result, the stone will appear less lively – and even dull.

When a diamond’s mined, diamond cutters assess the rough diamond to determine the best possible cut and shape to maximize its size and natural qualities. Whatever the form, the triple X diamond is the best choice.

By the way, “triple X” diamond stands for “Triple Excellent” diamond – meaning an excellent cut, excellent polish, and excellent symmetry.

However, if your budget’s tight and you want to save some money, you can go for Very Good or Good cut grades – and you will still get a solid amount of brilliance, fire, and scintillation.

Related Read: Which Diamond Cut Sparkles The Most?

Deeper Dive Into A Diamond’s Cut

Diamonds are cut with the goal to maximize brilliance, fire, scintillation, and overall visual appearance. So, in that sense, the cut is a measure of light’s performance as it hits a stone. 

Diamond’s cut affects the amount of light performance achieved. The locations, angles, shapes, and sizes of facets will determine the sparkle of a diamond.

Cut Scale: The Factors

Once a diamond has been processed, experts can grade its cut quality. GIA grades diamond’s cut by precisely measuring the sizes and angles of all the diamond’s facets.

Polish and symmetry can also play a minor role. All these aspects come together to determine the diamond’s cut grade.

Each diamond shape has an ideal cut proportion. You can simply ask one of the gemologists to point out a few options if you’re looking for an ideally-cut stone.

The Cut Scale

Fair And Poor:

Diamonds with a considerable amount of leaking light earn these grades. These stones tend to leak a significant amount of light due to the fact that they’re cut too shallow or too deep.

These gems provide slight brilliance and are generally less visually appealing. This cut category makes the top 35% of gem-quality diamonds. We recommend avoiding these gemstones since they won’t make for sparkling jewelry.


These are well-cut stones that capture light and possess a decent amount of sparkle. However, “Good” cut diamonds do have some light leakage – but all in all shine bright.

Good cut diamonds might have noticeably smaller or larger measurements than perfectly cut stones of the same shape. Diamond cutters may intentionally cut them to Good proportions to attain a particular style or look.

The top 25% of gem-quality diamonds have this cut grade. Good cut stones can be a good mix of size and value, but be careful and always ask a professional to evaluate the particular gem before you make a purchase.

Very Good:

Very well-cut stones that capture nearly all the potential of the diamond. These are very brilliant with minimal amounts of light leakage. 

Diamond cutters often intentionally cut diamonds to achieve a Very Good cut grade to improve the other factors of the stone, such as clarity and color. The top 15% of gem-quality diamonds are Very Good cut. 

These stones are a great choice if you’re looking to maximize the value of other factors, as well.


The highest cut grade represents the top quality diamond in the world. Stones with an “Excellent” cut grade are skillfully crafted and cut with precision, unleashing the maximum potential of sparkle and brilliance.

Little to no light leakage occurs in these diamonds as light passes through them. This premium category accounts for the top 3% of gem-quality diamonds.

With improvements in manufacturing technology and cutting methods, Excellent cut diamonds are increasing. An excellent cut stone is always a fantastic choice regardless of its size and shape – although it comes with a higher price tag.

Light Performance

A diamond’s cut reflects the brilliance, fire, and scintillation you see from it – or, in other words, the light performance.

The light performance consists of three factors – reflection, refraction, dispersion. The better a diamond can reflect and exhibit light, the better it will shine and sparkle more in your jewelry – and that’s what adds to its beauty.


When a diamond is tilted and rocked at different angles, a certain amount of light reflects on the facets’ surfaces rather than bouncing within the gemstone – and this occurrence is referred to as reflection. 

Usually, around 17% of light is reflected by the diamond.

Reflection should be balanced, though. If a diamond’s facets are too big, you can see reflections either weaken or strengthen too much – which will result in the diamond looking lifeless and dull.


The ideal diamond is cut so that light enters, bounces within, bends, and exits from the gem’s top. This occurrence is known as refraction.

Diamonds boast a refractive index of 2.41, which is pretty high and gives them their sparkly and shiny characteristics. 

The stone’s refraction is most noticeable with the ideal cutting technique and proportions. When the gem is well-cut, light refracts perfectly within the stone.


Did you ever notice that a diamond isn’t entirely black and white, but instead, you can see colors of the rainbow reflecting from the inside of the diamond? That’s a result of the occurrence called dispersion. 

As light bounces within the diamond, it bends and then leaves out of the gemstone and back to the viewer’s eyes. Its dispersion is measured at 0.44.

The visibility of this colored light is what gives diamonds their unique beauty. Other gemstones usually don’t have the same dispersion that diamonds possess. 

Therefore, diamonds are considered the best and most popular choice for engagement rings.

Finish: Polish, Symmetry, And Facets

Other factors that will impact the diamond’s cut grade – and, in turn, its light performance – are the polish, symmetry, and faceting.

Diamonds are generally cut in two ways – brilliant cuts and step cuts.

Brilliant cuts, most commonly round and Princess cut diamonds, can unleash the maximum potential of light performance. They have more facets than other cuts – and these facets are triangular and kite-shaped.

Brilliant gem cuts possess a high degree of sparkle and maximum brilliance, fire, and scintillation.

Step cuts – such as emerald and Asscher cut diamonds – also have a decent amount of sparkle and fire. These cuts have facets that resemble a staircase and are simpler in their presentation.

Moreover, they’re considered very elegant. 

Now, step cuts maximize the diamond’s scintillation. But since step cuts have fewer facets, they don’t reflect as much light as brilliant-cut diamonds. 

While step cuts have a unique beauty, it’s crucial to consider what type of sparkle you want your diamond to possess.

Moreover, polish and symmetry are both a result of the production process. 

The polish refers to the smoothness of the facet surface. If minor striated polish marks remain, it may impact light performance and, thus, diamond cut grade.

The other characteristic – symmetry – refers to the patent and evenness of facets’ shapes, sizes, and locations. If the facet’s placement is incorrect, the light performance – and a gem’s cut grade – are impacted. 

For example, an off-center table facet can reduce a diamond’s sparkle.

Related Read: What Makes Diamonds Lose Their Sparkle?

Pricing Effect

Like the other diamond’s factors, the cut grade can significantly affect pricing. 

We currently see the highest number of Excellent cut diamonds on the market to date. The improvement of the manufacturing technology of diamonds allows cutters to be more precise in their cutting practices, making them more available.

With round brilliant cut gems, an excellent cut grade can have a 5%-10% premium over the Very Good cut grade. The same applies to going from a Very Good cut to a Good cut grade.

Fancy shapes don’t have GIA assigned cut grades since they can have a variety of lengths and widths, all while maximizing brilliance.

Selecting Cut Grade

The cut is often considered an essential factor of a diamond. When choosing a diamond, it’s critical to ensure no light leaks from the stone. 

Now, excellent cuts are most premium, while Very Good cuts offer more value. The differences in brilliance and sparkle are subtle but are noticeable when compared side by side. 

Generally, we recommend maximizing the cut grade before anything else if possible.

Fancy-shaped diamonds have fewer restrictions since beauty is in the eye of the beholder. But still, you can usually go a grade lower with non-round brilliant-cut diamonds. Keep in mind that excellent cut fancy-shaped diamonds are pretty rare, though.

Ultimately, it’s up to you, and you must remember that there are plenty of other diamond aspects that impact its appearance and value. 

So, it’s best to decide which aspects and characteristics matter most to you.

Can Light Impact Diamond Brilliance, Fire, And Scintillation?

Have you ever noticed that in jewelry shops, the lighting is arranged in a way that enhances the diamonds’ brilliance, fire, and scintillation? 

That is because the light type the diamond’s exposed to is yet another critical factor that impacts how much brilliance, fire, and scintillation you’ll see in the diamond.

Not all types of light are equal; different types of light have varying concentrations, which impact specific characteristics of the diamond. And a good combination of light sources could maximize the diamond’s beauty.

For example, a direct beam of incandescent light could draw out the diamond’s fire since the beam suppresses white light in it. 

The gemstone darkens and draws attention to the colored sparkle, while diffused fluorescent lighting brings out the brilliance in a diamond because the light enters the stone from different directions.

Remember that the jewelry stores’ lights make the gem you’re looking at appear more brilliant and sparkly than it would be when viewed in daylight. 

So, be sure to observe the diamond you’re considering under natural light before you make a purchase!

Related Read: Why Does A Diamond Sparkle?

How Clarity Impacts Diamond Brilliance, Fire, And Scintillation?

Diamond’s clarity also affects its brilliance, fire, and scintillation. 

While clarity is part of its physical properties, brilliance, fire, and scintillation are optical effects that the diamond’s inclusions could diminish.

The larger and more numerous these inclusions a diamond possesses, the more likely they are to block light from bouncing around the stone properly. So, a diamond with an exceptionally high number of inclusions will always look dull no matter its cut quality.

While brilliance, fire, and scintillation are mainly used as indicators of the cut quality, they’re also an indicator of the diamond’s clarity.


So, what is diamond scintillation? 

Blinking flashes of light from different facets towards the diamond’s center as you move the gem is an occurrence called diamond scintillation.

Diamond scintillation isn’t the only light performance factor of a diamond, though. There are also brilliance and fire – and the combination of these three factors gives diamonds their uniqueness and beauty.

Of course, the maximum potential of brilliance, fire, and scintillation wouldn’t be possible without the cut. The better the cut grade of a diamond, the better the light performance.

So, if you want a diamond with the best brilliance, fire, and scintillation, ensure it has the highest cut grade possible.