Why do some diamonds look hazy and milky? What are the different colored lights that certain diamonds emit? Does it make the diamond a bad stone? And why do some diamonds shine in the dark while some don’t? You must have often thought about these things when thinking about buying a diamond. But never knew the right answers. We’ve put together all the important information and tips about diamond fluorescence here. These will answer most of your questions.
Fluorescence is a diamond’s propensity to emit colored glow when exposed to ultraviolet light. Diamonds can fluoresce in a variety of colors – blue, yellow, green, orange and white – but blue is the most common. Roughly, about 30 to 50% of all diamonds fluoresce to some degree. How does it happen? When exposed to invisible ultraviolet light, many diamonds luminesce and emit visible light. This light could be of different colors and varying strengths.
The Gemological Institute of America describes five levels of diamond fluorescence: none, faint, medium, strong and very strong. The strength of fluorescence does not directly correlate to either color or clarity. Hence, it is possible for two diamonds with completely different clarity and color grades to exhibit exactly the same strength of fluorescence.
Lab grown diamond fluorescence is caused by submicroscopic structures within the crystal. Blue fluorescence is most commonly associated with the presence of nitrogen atoms aligned in specific arrays within the carbon lattice. Most diamonds that exhibit strong blue fluorescence appear a bit hazy in regular light.
In most cases, fluorescence is just an identifying characteristic and not a performance feature. Hence, it is neither considered to be bad or good. But this question requires further exploration.
Fluorescence should be considered as a defect in certain cases. When the fluorescence is too strong, it makes the lab grown diamond appear cloudy. As a result, its transparency and eye appeal decrease. It makes the lab grown diamond hazy. In such a case, it is considered bad.
In some cases it is considered good. Medium to strong blue fluorescence tends to mask yellow body color so diamonds in the lower color range appear a shade whiter in lighting environments with sufficient ultra violet rays. In these cases it is considered good.
A number of recent studies have demonstrated that the fluorescence effect is diminished if the distance from the light source is increased. In most normal indoor viewing circumstances the distance from the light source is too great to bring out the fluorescence effect of the diamond. Therefore, the idea that the appearance of diamonds in lower colors is improved by fluorescence is largely false, making fluorescence neither good nor bad.
Something of prime concern in the recent years has been the possibility of over grading of color of diamonds. Laboratory color grading is done in light environments that contain UV light and the grading is done with the lab grown diamond in close proximity to the UV light source. This could affect the true color leading to higher color grading of these diamonds.
Studies have found problems in color grading accuracy of diamond fluorescence. One study revealed: If the grade on the report is higher than the real color and the appearance of the diamond does not benefit from the fluorescence under normal observation because of distance from the light source, then these diamonds actually look worse than the grade would indicate. Fluorescence can be considered bad in this case.
Earlier, blue-white diamonds with strong blue fluorescence were highly prized. They were diamonds in the colorless range with strong blue fluorescence and did not have any harmful visual effects. The term Blue White came to be used for diamonds that prominently displayed the milky effect. They were referred to as over blues, a term that is still used by the diamond industry.
Today, diamonds, mostly in the colorless range, are devalued based on fluorescence levels. In certain cases diamonds with strong fluorescence are discounted by 15% or more. Over the years there have been cycles of interest in highly fluorescent diamonds, but in the modern market many buyers are cautious about it.
Today, fluorescence is perceived in some negative ways:
1. It is assumed that the milky effect seen in strong fluorescence diamond is present because the diamonds are not of the best quality.
2. The purity of the diamond is doubtful because of the presence of a defect causing the fluorescent effect.
One of the most important studies undertaken to understand the visual effects of fluorescence on diamond was done by the GIA and published in Gems and Gemology in 1997.
Here’s how the study was conducted
The study involved carefully selected sets of diamonds in various colors and degrees of fluorescence. It involved three groups of observers: laboratory graders, jewelry trade members, and average observers. The diamonds were observed in a variety of specific lighting environments. The results of the study suggest that diamond fluorescence has little impact on visual appearance.
The researchers concluded:
1. Non-trade observers could not make meaningful distinctions in the diamonds. For this group, which was representative of the jewelry-buying consumers, fluorescence had no over-all effect on color appearance or transparency.
2.Data from the trained observers indicated a mild positive impact color in the table-up view, and even smaller negative impact on transparency.
1. As discussed earlier, fluorescence can have an impact on the color, appearance and pricing of a lab diamond and should not be considered a bad purchase. It is only in certain cases as discussed earlier, that one should be careful about buying a diamond with fluorescence. That is when fluorescence makes the diamond look hazy and milky.
2. If the lab grown diamond is H, I or J color, then look for a diamond with medium blue fluorescence. Why? It can make your stone look slightly whiter.
3. If the lab diamond color is G or higher, then the diamond should not have any fluorescence.
4. Whether lab-grown or mined, one must always buy a diamond that they like and it is an individual personal preference.
Now that you have the most important information and tips on lab grown diamond fluorescence, next time you log on to buy a diamond online, you need not worry about your diamond. With these tips and information, you are sure to buy a great lab diamond.
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