More and more often we are receiving clients who are not only familiar with “the 4 C’s” of diamond shopping, but are also making their preferences known regarding a diamond’s fluorescence. Unfortunately, a lot of the information they have acquired from their own research as well as from diamond dealers is misleading, conflicting and erroneous. So, what exactly is fluorescence, and how does it affect the appearance and value of the stone?
Fluorescence is a phenomenon that occurs in approximately 20% of gem quality diamonds. A diamond exhibiting fluorescence will literally glow a purplish-blue or sometimes a yellow hue when viewed under an ultraviolet (UV) light source such as a black light. It may also be activated when viewed under natural sunlight, a natural UV light source.
This characteristic in a diamond has been widely used to cast aspersions on other dealer’s stones, as well as to overvalue non-fluorescing diamonds. Typically, the dispensed advice takes the following forms:
- Blue Fluorescence (FL) is bad, stay away.
- FL in lower color diamonds, e.g.; I-J-K is a positive in that it will make the diamond face up whiter but only if the FL is faint or Medium, not Strong. In higher colors (D-H) it is detrimental; stay away.
- Strong FL is to be avoided at all costs.
- FL diamonds need to be priced and sold at a discount relative to comparable carat weight, color/clarity-cut diamonds that are non-FL.
The fact is that FL is not a negative, on the contrary it can be and is a positive factor. Several respected members in the trade have known and advocated this position for years.
In 1997, GIA (Gemological Institute of America) conducted an extensive study on the effects of blue diamond FL on visual perception. Both consumers and tradespeople were asked to evaluate the effects of fluorescence on their visual perception and to note any meaningful distinctions between non-FL to FL blue diamonds of differing FL intensities.
The results of this GIA study were highly instructive and surprising. GIA found that non-trade observers could not make ANY meaningful distinctions between non-FL to the FL blue diamonds and that FL blue diamonds had no overall effect on the diamond’s color or transparency!
The link to this GIA study is here: http://www.gia.edu/pdfs/W97_fluoresce.pdf
This is a very important study and is recommended reading consumers and should be required reading for all diamond and jewelry professionals. The bottom line? There are no grounds to consider blue diamonds in a negative light and therefore no basis for price differentiation relative to non blue diamonds.
(KingOfRocks.com is a Montreal-based online jewellery retailer focussing on quality diamond and gold pieces, offered at reasonable prices and provided with the very best of customer care. )
