Fluorescence
The fluorescence of diamonds is one of their most discussed, yet misunderstood, characteristics. Although often considered a negative trait, it is actually a natural phenomenon that, under certain conditions, can positively impact both their appearance and commercial value.
When the term «fluorescence» appears in diamond grading reports or online, it usually leaves most buyers confused. What exactly is fluorescence, and should it affect your choice when buying a diamond? The truth is, most people misunderstand fluorescence, which is one of the most complex and captivating characteristics of a natural diamond. The informed buyer can leverage fluorescence to gain beauty, rarity, and even value benefits.
Fluorescence is not a treatment or enhancement. It is a natural characteristic that reflects a diamond's geological history and is most commonly found in natural diamonds, where it can also serve as an indicator of natural origin.
Fluorescence is the property of certain diamonds to emit visible light when exposed to ultraviolet (UV) radiation. This light, usually blue, ceases to be emitted as soon as the UV source is removed, which distinguishes fluorescence from phosphorescence, a phenomenon quite rare in natural diamonds.
On a scientific level, the phenomenon is due to imperfections in the diamond's crystal lattice and the presence of trace elements such as nitrogen, boron, and aluminum. During the absorption of ultraviolet energy, electrons are excited and re-emit part of the energy as visible light.
Approximately one-third of natural diamonds exhibit some degree of fluorescence. The most common color is blue, but yellow, white, green, orange, and even red fluorescence are encountered less frequently.
Gemological laboratories classify fluorescence into five intensity grades: None, Faint, Medium, Strong, and Very Strong. This classification is based on laboratory observation under controlled conditions of ultraviolet lighting.
The effect of fluorescence on a diamond's appearance depends directly on its base color tone. In diamonds of grade I and below, blue fluorescence can optically counteract the yellowish hue, making them appear whiter in natural light.
Conversely, in high color-purity diamonds (D–F), strong fluorescence is often considered undesirable, as a small percentage of them may exhibit a milky or oily appearance, reducing their brilliance and transparency. This percentage is extremely low and does not justify the myth that diamonds with fluorescence are of lower quality.
Consumer psychology also plays an important role. Myths surrounding fluorescence often lead to the unwarranted rejection of quality diamonds. Proper information and visual inspection in natural light are crucial.
Fluorescence began to concern us when a large quantity of fluorescent diamonds was discovered at the Premier mine in South Africa. From there, the term «premier» arose to describe light yellow diamonds with strong blue fluorescence. Similarly, the term «jager» referred to diamonds from the Jagerfontein mine, also in South Africa, which produced a high percentage of colorless stones with strong fluorescence. These diamonds were known as «blue-white» (Blue Blanc) and had a higher price. This was due to the prevailing belief that fluorescence added value to higher color grade diamonds.
However, the positive associations connected with the term «blue-white» began to erode when the trade started selling lower-color diamonds with the «blue-white» label. In the Greek market, we often encounter the term Blue-Blanc for diamonds sold up until the late 1970s. These diamonds were usually slightly yellowish with a strong fluorescence that masked their slightly yellowish hue. They were quite popular, both because of their more attractive price due to their actual hue, and because of their name, which gave them French elegance.
The negative view of fluorescence began when it was revealed that laboratories in South Korea had overestimated the color of fluorescent stones in the early 1990s. Local consumers suddenly realized that their stones were overvalued and stopped buying fluorescent stones.
Exactly the same thing happened when it was revealed that the American laboratory had overestimated diamonds exhibiting fluorescence for several years. Up to 3 color grades due to the use of lamps with strong UV light during the examination process.
Around the same time, a large volume of diamonds began to circulate on the market. Diamonds that exhibited fluorescence, mainly from mines in Russia.
Is Diamond Fluorescence Good or Bad After All?;
Fluorescence is not a flaw. The structural integrity of a diamond remains unaffected by fluorescence. Fluorescence emerges naturally from within the diamond, representing its complex and captivating formation process. Some collectors and connoisseurs even seek it out for its rarity and visual appeal. Especially when it glows intensely under ultraviolet light, making the diamond appear almost alive.
For quite some time, the phenomenon we've nicknamed "semi-permanent" in the lab has been appearing frequently. At nail salons, UV lamps are used to dry manicured nails. Often, women wear their rings. And naturally, the UV light excites some of the diamonds set in the jewelry, causing them to appear blue.
In conclusion, diamond fluorescence is a distinctive natural characteristic. It reveals an additional story about the stone and its natural formation. The presence of fluorescence in diamonds should generally not deter you from purchasing them. But it can actually persuade you to buy one. Proper evaluation should be done in conjunction with the diamond's other characteristics. With knowledge and experience, it can turn into a significant advantage both aesthetically and financially.
Therefore, the next time you shop for the perfect diamond and see “Fluorescence: Medium Blue” on your diamond grading report, don't hesitate. This diamond could be an excellent choice for this very reason. A diamond should always be seen in person and not judged solely on a gemological assessment or a photograph.
Before the 1990s, certifications were common only for diamonds over one carat with high clarity and color grades. This began to change in the mid-1990s with the development of online diamond trading platforms. Gemological reports became essential for remote transactions, especially for international business-to-business trade, as India began to handle the majority of diamond cutting.
Soon, even smaller diamonds of lower quality were sent to laboratories for certification. Clearly, many of the diamonds of all sizes that received certification during that period by those laboratories would today receive a lower grade regarding the categorization of their color intensity.
Under normal lighting conditions, fluorescence is invisible to observers, including professional gemologists. A subtle but sometimes dramatic glow only becomes visible under ultraviolet light. A diamond's blue fluorescence can actually have a positive visual effect under normal lighting conditions. And this positive effect is even more noticeable in diamonds that have lower color grades ranging from the I color and below.
Since blue is the complementary color of yellow, a diamond with a faint yellow hue can appear whiter or more colorless when viewed from above. Because of this, medium to strong fluorescent diamonds can appear more appealing than non-fluorescent diamonds that share the same color grade.
Sunlight contains ultraviolet rays, so theoretically, diamond fluorescence can be activated outdoors. However, in practice, fluorescence is almost never noticeable in ordinary daylight. The intensity of UV radiation in natural daylight is much weaker than that of a gemological UV lamp. This means any fluorescent reaction is at best subtle and usually invisible to the naked eye. Even diamonds with strong or very strong fluorescence will look completely normal outdoors.
For some years now, the prevailing view has been that fluorescence can make a diamond appear «milky» or «oily.» However, although some share this concern, scientific studies of fluorescence have revealed that less than 0.2% of fluorescent diamonds exhibit this cloudiness, and even then, it is often due to unrelated internal characteristics rather than the fluorescence itself. Haze in a fluorescent diamond is an extremely rare phenomenon.
Source: www.iglcert.gr
