Sparkle and shimmer are fundamental characteristics of a diamond. Almost everyone has seen a diamond dazzle in the light. But have you ever seen a diamond glow? This phenomenon, known as diamond fluorescence, can cause diamonds to glow from within, emitting blue, white, green or even red light. Let’s examine the fascinating world of diamond fluorescence, illuminating what it is, how it affects diamonds, and what you should consider when choosing diamonds with fluorescence.
What is diamond fluorescence?
Diamond fluorescence, present in roughly 30% of all diamonds, is the emission of visible light when ultraviolet (UV) light (also known as black light like you might find in a nightclub or used in crime investigations) is shined on a diamond. Trace elements like nitrogen or boron in the diamond cause the emission of light. These elements absorb and re-emit UV light, creating a glow in some diamonds. While most diamonds fluoresce blue, they can differ in color depending on what elements or impurities are present in a particular gem.
Different colors of diamond fluorescence
The elements present within a diamond (and the quantity of those elements) will determine the color and intensity of a diamond’s fluorescent glow. Some diamonds with minimal fluorescence will hardly emit any noticeable light at all, while diamonds with heavy fluorescence can glow intensely. Two key elements are responsible for causing a diamond’s fluorescence:
- Nitrogen. The most common cause of blue diamond fluorescence is nitrogen, present in roughly 75% of diamonds.
- Boron. When it comes to diamonds with yellow or green fluorescence, boron is usually the culprit. This type of diamond fluorescence is rarer, as boron is only present in roughly 2% of all diamonds.
Does fluorescence affect a diamond’s appearance?
The 4Cs system of grading diamonds (cut, clarity, color and carat) does not directly address fluorescence. However, a diamond’s fluorescence can impact its appearance and is graded on this diamond fluorescence scale:
- None: No visible glow under UV light.
- Faint: Emits a weak glow, barely noticeable.
- Medium: A more distinct glow but doesn't affect the diamond's face-up appearance.
- Strong: Emits a bright glow, potentially noticeable under some lighting conditions.
- Very strong: Emits a very strong glow, possibly affecting the diamond's brilliance.
A diamond's color overall is graded from D (colorless) to Z (light yellow or brown) in the 4Cs grading system scale. Those that fall in the D through F grade range exhibit virtually no color, while those further down the scale will start to show a yellow or brownish tint. This tint is often canceled out by the blue glow caused by fluorescence, making some diamonds appear much whiter and brighter.
Does fluorescence affect a diamond's price or structure?
As would be expected, gems with an icy, bright-white look (graded D through F) tend to hold the highest price tag. As you move down the color scale (diamonds with a G, H, I, J, etc. color), faint traces of color become more apparent. Here’s how fluorescence can impact diamond value:
- Higher color grades (D-F): Even if the fluorescence has little to no impact on a D-F-graded diamond, its existence may slightly reduce the price because some perceive it as a defect.
- Lower color grades (I-M): Faint to medium fluorescence can cancel out natural color tints in lower-grade diamonds, making the diamond appear whiter—and potentially increasing its price.
- Visibility: Fluorescence should ideally not be visible to the naked eye under normal lighting conditions. Strong or very strong fluorescence might affect brilliance, which is not desirable. The glow emitted by diamond fluorescence can also shine light (literally!) on other imperfections within the diamond that may have otherwise gone unnoticed, making them appear hazy, cloudy or milky.
Note: Despite having the ability to wildly impact a diamond’s appearance, these visual manifestations do not weaken or change the structure of the diamond. A diamond that produces a fluorescent glow under UV light has the same structure as one that does not.
Famous fluorescence in diamonds
- The Hope Diamond. The public perception of diamonds with fluorescence is indeed a moving target. However, one diamond stands out, regardless of these perceptions: the Hope Diamond. Weighing in at 45.52 carats and celebrated for its mesmerizing blue color, the Hope Diamond is an excellent example of strong fluorescence in a diamond. In ultraviolet light, the Hope Diamond emits a stunning, rare red glow, which has led some to believe the diamond is cursed with bad luck.
- The Blue Moon Diamond. Found in South Africa’s famed Cullinan mine in 2014, the 29.62-carat Blue Moon Diamond's boron content causes it to radiate an orange-red glow when exposed to UV light. This caught the attention of researchers and jewelers, as this red glow has typically been seen in diamonds found in India.
- The Regent Diamond. Found in a Golconda, India mine between 1698 and 1701, the massive Regent Diamond weighed an astounding 410 carats. The near-flawless diamond emits a bluish tint caused by fluorescence.
If you have a diamond that glows, insure it with a personal jewelry insurance policy from Jewelers Mutual. It’s an affordable option that covers loss, damage and disappearance! You can check your rate online by clicking the button below.
