What Does It Mean When a Diamond Looks Blue?

Hey! I finally find the Answer!

Recently at the nail salon, I noticed an interesting phenomenon: my engagement ring, which I am sure is a real diamond, seemed to show a soft blue glow under UV light.

I was intrigued. So, the next time we were at the jewelers’, I made a point of asking why that was the case. He was gracious enough to explain, and also gave me some references to get more details. 

In this post, I will be sharing what I learned. What does it mean when a diamond looks blue? Why do you see it blue in some lights and not in others? Are there natural blue diamonds?


What Does It Mean When a Diamond Looks Blue?

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A diamond will look blue in several instances, including:

1. When a diamond has fluorescenceit will look blue, especially under UV light or sunlight. Fluorescence is a totally natural effect caused by certain mineral elements in the diamond.

This effect is not common; it occurs in only about a third of all diamonds. Fluorescence in diamonds will mostly be blue, although some may glow green, yellow, orange, or white. 

This is not to be confused with a diamond quality color grade, which evaluates how white or colorless a diamond looks. For this grading, the Gemological Institute of America (GIA) classifies diamond color quality by a letter between D and Z.

D is for the most colorless diamond, and Z is for a diamond that has a noticeable yellow or brown tint.

Fluorescence, on the other hand, should be visible only under UV light. You could have a diamond with the least color, for instance, F color, that shows a blue glow when you are at the club, under UV light.

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In rare cases, when the fluorescence is visible in sunlight, it means that the diamond has very strong fluorescence. The nail or the tanning salon are other places that use UV light where you are likely to notice fluorescence in your diamond.

The rest of the time, the diamond will look perfectly normal in other kinds of light.

The color grade of a diamond is not directly affected by its fluorescence, at least not on the certificate. However, it is important to note the benefits of blue fluorescence for a diamond of I color through to N color.

It helps the diamond look whiter. This is an advantage. Color being one of the 4C’s that determine the diamond quality and therefore price, you can get a more expensive-looking diamond for fewer dollars thanks to blue fluorescence. The cut, clarity, and carat are the other determining factors.


2. If it is a natural true-blue diamond,then, of course, it will look blue. But how does a diamond become blue in nature; you may ask?

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Blue diamonds are attributed to contamination of the diamond by trace quantities of boron during its formation in the earth’s mantle. True blue diamonds are quite rare and therefore very expensive.

They are classified as fancy diamonds, which are stones that exhibit all the properties of diamonds but occur in different colors. Blue diamonds come in hues ranging from blue-green to grey.

True blue diamonds are most valuable if the color is vivid and without a secondary color. The same 4Cs of connoisseurship: cut, color, clarity, and carat, govern their grading.


3. If blue color is added to a lab-grown diamond. While blue diamonds can be found in nature, they can also be produced in a lab.

Since the 1950s, several methods have been used to change a diamond’s appearance, such as adding color to a colorless stone.

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These enhanced diamonds do not have the value of natural blue diamonds, nor do they look as attractive. The other kind of manmade blue diamond is synthetic diamond.

Making diamonds is possible because they are essentially carbon, and carbon is abundant on the earth, in various forms. With the right lab conditions, replication of natural diamonds was always a matter of time.

The diamonds thus produced have the same properties as natural ones but are not as rare nor as valuable.


Do Real Diamonds Glow Blue?

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Yes, about 30% to 35% of real diamonds will glow blue in UV light. This is due to fluorescence.

Fluorescence, however, has nothing to do with the realness or lack thereof of jewelry purporting to be a diamond. You need a reliable jeweler or gemologist to help you determine that.


Do Diamonds Have a Blue Tint?

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Yes, there are some rare naturally blue diamonds that have a distinct blue tone attributed to the presence of boron in their structure.

Blue diamonds, when compared to other diamonds, are found deeper in the Earth’s mantle, with the boron credited for the blue color originating from rocks carried to the mantle by moving ocean tectonic plates. Natural blue diamonds are among the most expensive gemstones.


Why Is My Diamond Blue in The Sun?

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Your white diamond is blue in the sun because of the very strong level of fluorescence in it. The GIA regards diamond fluorescence as a distinguishing characteristic rather than a grading factor.

The GIA scale for fluorescence gives five degrees of intensity, which are: none (majority of the cases), faint, medium, strong, and very strong. 

The intensity of fluorescence that a diamond bears are listed on the GIA report, which should be available to you when purchasing it.



Diamonds that have fluorescence are neither bad nor good. It depends on individual tastes and circumstances.

Blue fluorescence can make a lower-color diamond appear whiter and more beautiful.

It can also be a source of intrigue like mine. In other instances, fluoresce has been blamed for making a piece look hazy.

At the end of the day, it’s entirely up to the owner and how they feel about the diamond.

Hey! I finally find the Answer!