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Do Diamonds Glow Under LED Light?

Do Diamonds Glow Under LED Light?

Diamonds are billions of years old – and are the most valuable stones on the planet. These gems are as white as ice, as clear as water, and even stronger than nails. 

But the thing that truly distinguishes these precious gems is the way they interact with light. Nothing shines brighter than a diamond – one of the many reasons we have a “Shine bright like a diamond” phrase.

Nevertheless, have you ever wondered why diamonds shine? Why do diamonds sometimes change color under particular lightning? Do diamonds glow under LED light?

Set aside a few minutes and read the whole thing.

Why Do Diamonds Shine?

When a diamond is mined, the color, clarity, and most of the carat weight have already been established by nature. A rough diamond, on the other hand, resembles a transparent rock. It’s not glistening, and it doesn’t make rainbows appear. 

Moreover, it doesn’t play with light. So, what makes a diamond shine?

A diamond’s cut is what makes it shine in the spotlight. It isn’t something that just happens; it’s the outcome of the diamond cutter’s expert artistry.

Diamond cutting alters a diamond’s original shape. The actual beauty of a diamond comes from the expertise of the diamond cutter, who creates it from a tiny crystal in the ground.

The cutting procedure contributes significantly to the value of a diamond. A diamond’s cut and dimensions can impact its value by up to 40%. 

As a result, a considerable deal of work and effort goes into cutting a diamond to release its beauty and its worth.

Our predecessors had to learn how to utilize diamonds to polish diamonds over hundreds of years. When our society created contemporary diamond cutting, it released the brightness that comes from the diamond’s unique optical properties.

Instead of the conventional saw, today’s diamond cutting procedure frequently begins with lasers cutting the rough gem into pieces. However, diamond cutting requires as much care as ever after that. 

The cutter grinds and polishes each facet gently using a wheel covered with diamond dust. It takes time and talent to do it properly. Diamond cutters add 58 perfectly polished facets that will capture light to produce the glitter of the round brilliant diamond

The angles, dimensions, and alignment of the facets guide light within the diamond, resulting in what we recognize as “brilliance.” The diamond’s facets act as a hall of mirrors, reflecting light from all directions and returning it to your eyes.

The cutter does this by precisely calculating the angles. If the depth is too shallow, the light just goes through. And if you go too deep, it will ooze out the side rather than hitting the eye with sparkle. 

Either way, your diamond will have black areas. That is why a poorly cut diamond seems to be made of glass. Brilliance, fire, and scintillation are three distinctive visual aspects of a well-cut dazzling gem. 

Diamond Brilliance

As we’ve already established, the cut of a diamond determines its brilliance. Light entering a diamond is reflected back into the eyes when it is cut at precisely the correct angle.

Having said that, diamond brilliance is the reflection of white light.

A properly cut diamond is cut in such a way that the light that enters the diamond is reflected to the spectator. That is owing to the cut’s angle. However, only a small portion of the light is reflected back; the remainder is routed through the diamond.

A diamond cut at an angle that is too shallow will not reflect much light. That’s due to the fact that light will be reflected off the diamond’s bottom – the light wouldn’t be reflected back and in your direction as a viewer.

Light will be reflected out the side of the gem if the diamond is cut at an excessively deep angle – and it won’t shine nearly as much as a well-cut diamond.

Diamond Scintillation

Scintillation refers to the contrast of light and shadows within a diamond, as opposed to brilliance, which is the white light that lights a diamond. When a gemstone is set in jewelry, scintillation causes it to sparkle when the wearer moves.

The light characteristics of a well-cut diamond should be balanced. While brightness or fire may draw more attention, having too much of one characteristic may detract from the overall beauty of the diamond. 

Each light adds to the diamond’s brilliance by strengthening the others. The shadows of scintillation let white light stand out, and the shift in patterns draws attention to the stone.

The facets surrounding the girdle are among the cut features that impact scintillation. The upper and lower girdle facets must be precisely oriented to aid in scintillation. 

If there’s too much white light or the diamond has big bright patches, it will significantly reduce the contrast. Disproportionate quantities of darkness detract from the radiance of diamonds, which is one of their main selling points.

When looking for a diamond with attractive scintillation, bounce the stone back and forth softly. Look for prominent facets on the girdle’s edge. Examine the stone for any dark areas visible from the table or the edges. 

Because you’re the one who selects the diamond, it is critical that you select one with a scintillation pattern that appeals to you.

Diamond Fire

Light bends as it goes through a diamond. When light travels through a diamond, it divides into multiple colors. Water droplets exhibit the same effect when a rainbow develops – or even when light travels through a prism.

That implies that a ray of white light passing through a diamond would produce a rainbow of colors. We call this “fire” – when we see the colors of the spectrum in a diamond.

There are certain diamond cuts that have more “fire” than others. Emerald-cut diamonds, for example, have more fire but less brilliance. Brilliant-cut diamonds, on the other hand, have more brilliance and – you guessed it – less fire.

The Impact Of A Diamond’s Fire, Brilliance, And Scintillation

The right combination of fire, brilliance, and scintillation brings a diamond to life. There aren’t many gemstones that offer this overall impact. 

But we must remember that diamonds lack brightness, fire, and scintillation in the absence of light. Only a few gemstones can achieve the impact that light has on a diamond.

The Ideal Brilliance

The optimum diamond brightness is a matter of personal taste. A diamond with fewer facets has less brightness. That is because the gem has fewer angles from which to reflect.

A diamond with fewer facets has more fire, though. It also emphasizes a diamond’s clarity. The brilliance of a diamond with numerous facets on its top surface will be higher. It’s up to you and your preferences to choose between brilliance and fire.

Look for “Triple Excellent” diamonds if you want the maximum brilliance. Triple X diamonds are another name for them. These diamonds are flawless in terms of cut, polish, and finish. They’re well-known for the desired shimmer that comes with brilliance.

Other Factors That Determine Diamond’s Shine


Symmetry, a portion of how the diamond is cut and formed, is one of the most important aspects of a diamond having the maximum brilliance. 

The diamond must be perfectly even on all sides, with all facets cut to perfection. The light will not refract appropriately if the symmetry is even slightly wrong.

See Also: Do Diamonds Refract Light?


The brilliance of a diamond is influenced by its clarity to a lesser extent. The quantity of light that may enter the diamond is limited by imperfections on its surface. 

Inclusions obstruct the free movement of light within the diamond. Just like stop signs and speed bumps, these flaws have an effect on how light travels. 

Fewer flaws equal a more dazzling diamond since there is nothing – or virtually nothing – to distract from the brilliance and glitter.


After the gem has been precisely cut and fashioned to bounce light properly, it’s meticulously polished to its final degree of brilliance. The diamond’s brilliance is permanently affected by polishing

Any remaining roughness or imperfections on the outside of the stone are gradually eroded – and a thorough polish can genuinely bring out the brilliance of a diamond.

The Reason Behind The Price

It’s not simple to make a diamond sparkle and shine the way it should; highly experienced specialists must understand how to cut and polish each precious stone to achieve the most outstanding results. 

You may see the benefits of their hard work every time you observe how a diamond throws a magnificent display of light and color when your hand is in motion. 

Also, a big part of what makes diamonds such a precious and beloved gemstone is their scintillation or the vivid rainbow of light and hues.

See Also: Why Does A Diamond Sparkle?

Diamond Fluorescence

The impact of UV light on a diamond is known as diamond fluorescence. A diamond glows blue when exposed to ultraviolet light (also known as blacklight). 

You might see various colors in a diamond, such as yellow, green, red, or white – but blue is the most frequent fluorescent color. 

Now, let’s simplify the concept of diamond fluorescence. 

When you’re at a nightclub, and you’re exposed to blue or ultraviolet light, your teeth might shine white and appear brighter. Well, similarly, a diamond shines when placed under a black light. 

However, not all diamonds exhibit fluorescence – fluorescence occurs in just 30 to 35 percent of diamonds. The diamond stops displaying fluoresce after the UV light source is withdrawn.

Why Does Fluorescence Occur In Diamonds?

Diamond is carbon that has crystallized. This process takes place 75-125 miles beneath the Earth’s surface, typically around volcanic or old volcanic areas. A diamond will turn luminous if the soil contains traces of the mineral boron during the crystallization process.

Fluorescence Levels

The fluorescence of a diamond is determined by turning it upside down and exposing it to UV light – and the fluorescence intensity will influence the price and look of a diamond. The GIA (Gemological Institute of America) evaluates fluorescence in the following way:

1. None

  • Under UV light, diamond exhibits no sparkle at all. Diamonds with no fluorescence are the purest and, as a result, tend to be the most expensive.

2. Faint

  • Under UV light, the diamond displays a very mild blue glow. Fluorescence that is too faint to be seen has no effect. However, you can save a few dollars if you buy higher diamond color grades (D-G).

3. Medium

  • Under UV light, there is a visible blue glow. Fluorescence of a medium intensity has little to no negative impact. In fact, it can aid in the appearance of a diamond with a little yellow hue (H – K).

4. Strong to Very Strong

  • When exposed to UV light, a vivid blue glow is seen. A diamond with a lot of fluorescence might look hazy or milky – especially if it’s a diamond with a lot of colors (G and above).

The Price Impact Of Fluorescence

The beauty of a diamond can be enhanced or diminished by fluorescence. A lower-color diamond (J-M color graded) might benefit from the bluish hue since it cancels out the light yellow, giving it a colorless look. Fluorescence, on the other hand, may have the opposite effect in a very high-color diamond (color graded D-F).

Fluorescence is believed to be present in around 30% of diamonds, so you’re likely to come across some of these stones while looking for a diamond.

But there is some good news! Due to the negative perception of fluorescence, diamonds of this grade are frequently sold at a discount. Here’s how it normally goes down:

  • Except for diamonds G and higher in color, diamonds with weak fluorescence are priced the same (no reduction). There’s a chance you’ll notice a 1% discount.
  • If the color is H or above, gems with mild fluorescence receive a small discount (2-7%).
  • If the color is H or higher, diamonds with strong – very intense fluorescence receive a larger discount (3-15%).

The Bad Impact Of Fluorescence 

On colorless diamonds, fluorescence has a more detrimental impact. Colorless gems with a strong to extremely strong fluorescence might seem hazy and greasy. 

The diamond seems less translucent as a result of that. When contrasted to a diamond with no fluorescence, even a casual viewer may often see the difference.

The Good Side Of The Fluorescence

Diamonds with lower color grades (H and below) generally benefit from fluorescence. A medium-strong blue fluorescence can help make diamonds below H seem whiter by counteracting the yellow hue. 

As a result, a diamond can usually appear one color grade higher. That is fantastic since it allows you to save money. Diamonds with a lower color grade are substantially less expensive. 

So, you may save a lot of money by purchasing a diamond that is lighter in color and has a strong fluorescence – all while having it appear whiter.

Read More: Why Do Diamonds Turn Blue In Blacklight?

Test Your Diamond Using A UV Light

You’ll need a black light for this one. Turn off the lights in your home and set the gem under the UV light. Wait for it to respond and see what color it gives out; most diamonds will glow blue, but not all of them will. 

Certain diamonds do not shine under UV light.  

If you notice a faint green, gray, or yellow fluorescence instead, the gem is most likely not a diamond. 

Bear in mind that it’s not a definite test, and not all diamonds will display a blue hue. Therefore, it’s better to have a diamond specialist examine your precious stones using their modern equipment.

Read More: Can Ultraviolet (UV) Light Destroy A Diamond?


So, do diamonds glow under LED light?

Yes, they most definitely do. Of course, let’s not forget that several factors determine one diamond’s shine – the most important being the matter in which the gem is cut to perfection.

Diamond will also shine under UV or so-called black light. However, as we learned, the more fluorescence one diamond shows, the less value it has.

But in the end, fluorescence is a matter of personal preference. And the best part? Fluorescent diamonds are usually much cheaper, and sometimes you won’t even notice the difference!