Blue Fluorescence in Diamonds: What Does It Really Mean?
When it comes to diamonds, there’s a lot of fascination—and confusion—around blue fluorescence. Is it good? Is it bad? Does it make your diamond look dull, milky, or better than non-fluorescent stones? These are questions I get asked often during consultations, so let’s unravel the mystery of blue fluorescence in diamonds together.
What Is Blue Fluorescence in a Diamond?
Blue fluorescence is a natural characteristic found in some diamonds. When exposed to ultraviolet (UV) light—like sunlight or a blacklight—these diamonds emit a soft blue glow. The effect ranges from faint to very strong, depending on the stone. While this may sound unusual, fluorescence is actually quite common, with around 30% of diamonds exhibiting some level of it.
But what does this mean for the appearance of your diamond? That’s where things get interesting—and where misconceptions often take over.
Image: Diamonds shown under UV light to highlight florescent effect in diamonds which have strong florescence
Blue Fluorescence Diamonds Are Bad, Right?
Well, as co-Owner of Morgan & Co owner, Laura Penkalla, aptly puts it: “It depends.”
The debate around blue fluorescence in diamonds seems never-ending. Much of the confusion comes from misinformation, outdated ideas, and a lack of understanding about what actually causes certain visual effects. In actual fact, when chosen carefully, diamonds with blue fluorescence can actually look better than non-fluorescent stones.
What Causes a Diamond to Look Blue in Sunlight?
The appearance of blue in a diamond isn’t always fluorescence at play. Often, it’s simply a reflection of the blue sky. Diamonds are expert light performers, so they reflect and refract colours from their surroundings, including the sky above.
Fluorescence only affects the diamond under UV light, and when paired with certain inclusions, it can sometimes create a milky or cloudy effect. However, this isn’t true for all fluorescent diamonds. Experts, like our diamond sources at Morgan & Co, perform rigorous tests to ensure the if a diamond is chosen which has fluorescence that it enhances their beauty, not detracts from it.
Debunking Misconceptions About Fluorescence
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“Fluorescent Diamonds Look Dull”
Not necessarily! The level of fluorescence in a diamond doesn’t automatically make it dull. For example, a diamond with strong blue fluorescence can appear brighter and whiter in shaded daylight, especially if it’s masking a slight yellow tint. -
“Fluorescent Diamonds Are Milky”
While some fluorescent diamonds can appear milky, this effect is often due to certain types of inclusions that interact with the UV light. Skilled diamond sources reject these stones. A well-selected fluorescent diamond will appear just as clear and brilliant as a non-fluorescent one, indoors and outdoors.
How Fluorescence Can Enhance a Diamond
Here’s the surprising part: blue fluorescence can actually improve the appearance of certain diamonds. Strong blue fluorescence often counteracts yellow undertones in diamonds graded G or lower, making them look whiter in daylight.
For example, a G-colour diamond with blue fluorescence might look closer to a D-colour diamond—saving you money while still achieving a stunning look. This often comes into play when we are choosing a natural diamond and need to stick to a client's budget.
Natural Diamonds vs. Lab-Grown Diamonds: Fluorescence and Pricing
When purchasing a natural diamond, you may find yourself having to compromise on certain factors, such as size, quality, or the presence of fluorescence, to stay within your budget. However, lab-grown diamonds—thanks to their lower price point—offer more flexibility. You can prioritise higher quality, including better color and cut grades, without sacrificing affordability.
That said, fluorescence isn’t a “flaw” to avoid. Instead, it’s one of many factors to consider when choosing the right diamond for your budget and preferences.
The Final Word on Blue Fluorescence
Blue fluorescence in a diamond isn’t inherently good or bad — it’s all about context. When carefully selected, a fluorescent diamond can be as breathtaking as any non-fluorescent stone, sometimes even more so.
At the end of the day, the goal is to find a diamond that speaks to your style, fits your budget, and sparkles in every kind of light. Whether it glows blue under UV light or not, your diamond should be a true reflection of you.
Have questions about fluorescence or other diamond characteristics? Let’s chat during your private consultation—We are here to guide you every step of the way.
With Love,
Morgan xo
