Photographed by Michael Cowing
Here we have 8 diamonds with strong to very strong blue fluorescence photographed by Michael Cowing at ACA Gemological Laboratory under typical daylight balanced fluorescent lighting & longwave UV.
In the past, strong blue fluorescence was an indication that a diamond was natural and not synthetic. I learned that this is no longer always true during a Tucson AGTA talk by Julia Griffith from SSEF. Her recent research has indicated that it’s possible but uncommon for CVD synthetic diamonds to fluoresce a bluish color under deep UV, which can affect deep UV screeners.
She noted that since synthetic diamond production is evolving, adaptions to equipment designed for trade use must be made. It is increasingly important to do multiple tests to confirm a diamond is natural and not synthetic.
According to Griffith’s research, 79% of synthetic diamonds are now CVD-grown, 89% possess color grades of D, E, or F, and 95% have a clarity of VS2 or higher. That’s why GIA no longer grades synthetic diamonds with the color and clarity nomenclature GIA developed for natural diamonds. GIA reports only state if the man-made diamond falls into one of two categories, premium or standard. http://www.gia.edu/…/new-descriptive-terminology-for…
This photo is a cropped version of two Michael Cowing photos showing GIA’s 5 levels of diamond fluorescence: none, faint, medium, strong & very strong. You can see both non-cropped photos in my book: “Diamonds: Their History, Sources, Qualities and Benefits” (reneenewman.com/diamonds.htm) and in my “Diamond Handbook” (reneenewman.com/handbook.htm), a more in-depth book on diamond identification and grading.
Guest articles by Renée Newman:
https://gem-spectrum.com/category/renee-newman
About the author:
Renée Newman is a gemologist (GG, GIA), lecturer, writer and author of 15 books on gems and jewelry. Her goal is to provide consumers and jewelry professionals with unbiased, affordable information on how to buy, evaluate and appreciate gems and jewelry. She can be reached through her website:
