When examining a diamond, it’s common to observe a variety of colors that can reflect off the surface. One of the more intriguing colors is blue, which can be seen in certain lighting conditions. But what does it mean when a diamond appears blue? Are there natural blue diamonds, or is it a result of a certain treatment?

In this article, the author delves into the phenomenon of blue diamonds and aims to provide readers with a better understanding of why diamonds can appear blue, as well as exploring the possibility of natural blue diamonds. By sharing insights from a jeweler and additional research, the article offers a clear and informative explanation of this fascinating aspect of diamonds.

Key Takeaways

  • Diamonds can appear blue in certain lighting conditions, but it does not necessarily indicate a treated or synthetic diamond.
  • Natural blue diamonds exist and are incredibly rare, with only a small percentage of diamonds exhibiting this color.
  • Understanding the causes of blue diamonds can help consumers make informed decisions when purchasing diamonds.

What Does It Mean When a Diamond Looks Blue?

A diamond can look blue due to various reasons, including fluorescence, natural true-blue color, or artificial color added to a lab-grown diamond.


When a diamond has fluorescence, it can look blue, especially under UV light or sunlight. Fluorescence is a natural effect caused by certain mineral elements in the diamond. This effect is not common and 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.

Fluorescence 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. In rare cases, when the fluorescence is visible in sunlight, it means that the diamond has very strong fluorescence.

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, which 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.

Natural True-Blue Color

If a diamond is a natural true-blue diamond, then, of course, it will look blue. 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.

Artificial Color Added to a Lab-Grown Diamond

Blue color can be 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.

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.

In conclusion, a diamond can look blue due to fluorescence, natural true-blue color, or artificial color added to a lab-grown diamond. Fluorescence is a natural effect that occurs in only about a third of all diamonds and can help a diamond look whiter. Natural true-blue diamonds are rare and very expensive, while lab-grown diamonds with added blue color do not have the value of natural blue diamonds.

Do Real Diamonds Glow Blue?

Approximately 30% to 35% of real diamonds exhibit blue fluorescence under UV light. This phenomenon is caused by fluorescence, but it does not indicate the authenticity of a diamond. A trustworthy jeweler or gemologist should be consulted to determine the genuineness of a diamond.

Do Diamonds Have a Blue Tint?

Some diamonds have a blue tint, which is caused by the presence of boron in their structure. These rare blue diamonds are found deeper in the Earth’s mantle compared to other diamonds. The blue color comes from rocks carried to the mantle by moving ocean tectonic plates. Natural blue diamonds are among the most expensive gemstones due to their rarity.

Why Is a Diamond Blue in the Sun?

When a white diamond appears blue in the sun, it is due to the diamond’s strong level of fluorescence. The Gemological Institute of America (GIA) considers diamond fluorescence as a distinguishing characteristic rather than a grading factor. The GIA scale for fluorescence has five degrees of intensity: none (majority of the cases), faint, medium, strong, and very strong. The intensity of fluorescence that a diamond possesses is listed on the GIA report, which should be provided when purchasing it.


The presence of fluorescence in diamonds is a matter of personal preference and situation. Blue fluorescence, for instance, can enhance the appearance of a lower-color diamond, making it appear brighter and more attractive. However, it can also create a hazy effect in some cases. Ultimately, the decision to choose a diamond with or without fluorescence lies with the owner and their individual taste.

Stephanie, a jewelry designer and writer, emphasizes the importance of considering personal preferences when selecting diamond jewelry. Her expertise in fashion design and jewelry has given her a unique perspective on the subject. When it comes to selecting a diamond, it is important to consider the individual’s taste and circumstances to make the best decision.