Fluorescence is the visible light some diamonds emit when they are exposed to invisible ultraviolet (UV) rays.
The light emitted lasts as long as the diamond is exposed to the ultraviolet source. In more than 95% of the diamonds that exhibit this phenomena, the color seen is blue. In rare instances, the reaction
is yellow, white or another color.
Of the diamonds submitted to GIA over the past decade, approximately 25% to 35% exhibit some degree of fluorescence.
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.
The biggest study ever undertaken to understand the visual effects of fluorescence on diamond was done by the GIA and published in Gems and Gemology in 1997.
It was a controlled study of a carefully selected set of diamonds in various colors and degrees of fluorescence, and involving both trained jewelry professionals and non-trade observers.
The conclusions of the study suggest that diamond fluorescence has very little impact on visual appearance to the average viewer.
According to the authors of the study, “In general, the results revealed that strongly blue fluorescent diamonds were perceived to have a better color appearance when viewed table-up (flat-side up), with no discernible trend table-down (pointed-side up).
Most observers saw no relationship between fluorescence and transparency”. In many instances, observers preferred the appearance of diamonds that had medium to strong fluorescence.
Fluorescence does not compromise or affect the structural integrity of a diamond in any way whatsoever.
Grading laboratories include a diamond’s fluorescence and its strength on the grading-certificate because it is a permanent identifying characteristic unique to that diamond, and is considered neither good nor bad.
We hope this article has given you a bit more of a background on fluorescence, but should you have any additional questions about this or any other jewellery related topics, you can always: “Ask Our Jeweller”
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