Do Diamonds Glow Under Black Light?

Do Diamonds Glow Under Black Light?

Have you ever wondered what happens when you shine a black light on a diamond? It's a fascinating phenomenon that combines the worlds of science and jewelry in a mesmerizing display. At Caleesi Designs Jewelers, we're all about exploring the intriguing aspects of gemstones, and today we're diving into the captivating world of diamonds under black light.

Understanding Fluorescence in Diamonds

What is Fluorescence in Diamonds?

Fluorescence is the emission of visible light by a diamond when it is exposed to ultraviolet (UV) light, commonly found in black lights. This phenomenon can cause the diamond to glow, typically in blue or yellow hues, though other colors like green or white can also occur.

Causes of Fluorescence in Diamonds

The fluorescence in diamonds is caused by the presence of certain elements within the stone, such as nitrogen or boron. These impurities absorb the UV light and release it as visible light, resulting in the diamond's glow.

The Impact of Fluorescence on Diamonds

Perception of Color and Clarity

In some cases, fluorescence can enhance the appearance of a diamond, making it appear whiter or masking yellowish tints in lower-color-grade diamonds.

However, strong fluorescence can sometimes create a hazy or oily appearance in certain lighting conditions, which may affect the diamond's clarity.

Value and Desirability

The effect of fluorescence on a diamond's value varies. While it can be considered a desirable trait in some diamonds, particularly those with lower color grades, strong fluorescence might reduce the value of higher-color-grade diamonds.

Fluorescence in Different Diamond Shapes

The shape and cut of a diamond play a significant role in determining the visibility and impact of fluorescence. Here's a closer look at how different diamond shapes interact with this unique characteristic:

Round Brilliant Cut

  • Brilliance and Fire: The round brilliant cut is designed to maximize light reflection and dispersion, resulting in exceptional brilliance and fire.
  • Fluorescence Masking: The intense sparkle of a well-cut round brilliant diamond can often mask the effects of fluorescence, making it less noticeable in most lighting conditions. This makes the round cut a popular choice for diamonds with moderate fluorescence.

Step Cuts (Emerald, Asscher)

  • Large, Open Facets: Step cuts feature large, open facets that provide a clear view into the diamond. These cuts are known for their elegant, mirror-like appearance rather than their sparkle.
  • Fluorescence Visibility: The open nature of step cuts can make fluorescence more apparent, especially in diamonds with strong fluorescence. In these cases, the fluorescence can sometimes give the diamond a hazy or oily appearance, affecting its overall clarity and transparency.

Fancy Shapes (Oval, Pear, Marquise)

  • Elongated Shapes: Fancy-shaped diamonds like oval, pear, and marquise cuts have elongated forms that can create the illusion of a larger size.
  • Fluorescence Impact: In fancy shapes, the effect of fluorescence can vary. In some instances, it can enhance the perceived size and brightness of the diamond, while in others, it may be more visible and affect the diamond's appearance.

Princess Cut

  • Brilliance and Sharp Facets: The princess cut is known for its sharp angles and high degree of brilliance, similar to the round brilliant cut.
  • Fluorescence Interaction: Like round cuts, the sparkle of a princess cut can often camouflage the effects of fluorescence, making it a suitable choice for diamonds with this characteristic.

Balancing Factors

When selecting a diamond shape, consider how the cut interacts with fluorescence to achieve the desired visual effect.

Choosing a Diamond with Fluorescence

Personal Preference

The choice of a fluorescent diamond is largely a matter of personal preference. Some people are drawn to the unique glow and character it adds to the stone.

Viewing Conditions

It's important to view the diamond under different lighting conditions, including natural light and black light, to observe how the fluorescence affects its appearance.

Expert Guidance

At Caleesi Designs Jewelers, we're here to help you navigate the nuances of diamond fluorescence. Our team can assist you in choosing a diamond that aligns with your preferences and showcases its beauty in all types of light.

The Magic of Diamonds Under Black Light

Imagine walking into a room lit by black light, and your diamond ring starts to emit a soft blue glow, adding an extra layer of mystery and allure to your jewelry. It's a reminder of the hidden wonders within these precious stones, waiting to be revealed under the right conditions.


The phenomenon of diamonds glowing under black light is a fascinating aspect of these beloved gemstones. Whether you're drawn to the subtle glow of a fluorescent diamond or prefer a stone without this characteristic, the most important thing is to choose a diamond that speaks to you and adds a touch of magic to your life. Visit us at Caleesi Designs Jewelers, where our friendly team is ready to help you discover the perfect diamond, fluorescence and all. Don't forget to say hi to Chili, our store dog, when you stop by!

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