Medium Blue vs. Strong Blue Fluorescence Diamonds Pros and Cons

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January 21

Theresa writes: “Thank you for your wonderful site! My fiancé and I would like to purchase a Brian Gavin Blue diamond with one of his settings. My main query is, is it okay to buy a “strong blue” fluorescence or should I stick with a medium blue. Also, what color grade would you advise with a BG blue?

We are in Australia and would like something that is eye clean, 1-1.5 carats and have a budget of approx $9000 Aus dollars all up (a little more in USD). This would be with a simple white gold 4 or 6 prong band. Do you have any suggestions? Thank you so much in advance- your site is a God send!”

Medium Blue vs Strong Blue Fluorescence:

Well Theresa, let’s start with the understanding that the majority of diamonds which I have owned personally have exhibited medium to strong blue fluorescence. As a matter of fact, I’m a big fan of blue fluorescent diamonds. With that in mind, I definitely think that a diamond with strong blue fluorescence from the Brian Gavin Blue collection is a perfectly good option to consider!

Blue Fluorescence DiamondsThe visible difference between a diamond with medium blue fluorescence and one with strong blue fluorescence is simply that one will glow a more intense degree of neon blue when the diamonds are exposed to black light or strong ultraviolet light. There really isn’t really a difference that is going to be readily apparent when the diamonds are evaluated in normal lighting scenarios.

Technically speaking if we were evaluating two diamonds of the exact same color grade with one diamond having medium blue fluorescence and the other diamond having strong blue fluorescence, the color grade of the diamond with the strong blue fluorescence would likely appear to be slightly higher than the diamond with medium blue fluorescence because the fluorescence acts like a chemical whitewash and has a tendency to lift the color grade of a diamond slightly.

However, this is a statement which can be kind of misleading if taken at face value because each color grade is actually a range of color and thus every “H” color diamond is slightly different and thus it would be erroneous to imply that an H color diamond with strong blue fluorescence will look more like a G color diamond because it might actually be an H color diamond which is closer to an I in color.

Therefore, it is kind of difficult to ascertain what effect the fluorescence level is having upon the diamond in terms of the actual improvement in body color… so I tend to view the different levels of fluorescence within a diamond more as an identifying characteristic than a decisive factor in terms of my decision to purchase one diamond over another within the range of faint to strong blue fluorescence.

In terms of the combination of clarity and color to consider, it really is a matter of personal preference. However, I usually select something for myself in the clarity range of SI-1 to VS-1 with a color grade of F – I color because this tends to provide options which are “eye clean” to people with average vision and a crisp, clean white appearance in terms of the body color.

As a matter of fact, this combination of diamond clarity and diamond color tends to enable people to maximize the size of the diamond within their desired price range while averaging the range of clarity and color to something which tends to be acceptable for most people.  However, I strongly recommend looking at a range of diamond clarity and diamond color in person to establish the parameters of your personal preference before buying a diamond since it truly is a matter of personal preference.

Within the range of parameters which I stated previously as the basis of my own personal preference, I conducted a search for diamonds within the inventory of the Brian Gavin Blue collection and found a few viable options for you to consider:

This Brian Gavin Blue Diamond graded by the AGSL as weighing 1.227 carats, VS-1 clarity, I color with strong blue fluorescence is a very nice option! The primary inclusions consist of clouds, crystals, and pinpoint size diamond crystals. Basically, all you have are tiny diamonds that were trapped within the larger diamond crystal as it formed.

The diamond is graded on the AGS Platinum Light Performance grading platform with an overall cut grade of AGS Ideal. More importantly than that the high and low range of measurements for the crown and pavilion angle as indicated on the computerized proportions analysis we can see that the spread between those measurements is minimal with the average crown angle of 34.9 degrees being the result of a difference of 34.8 – 35.2 degrees and the average pavilion angle of 40.9 degrees results from a difference of 40.8 – 41.0 degrees, so there is very little variance.

To put this in perspective, the average crown angle of 34.8 degrees could also be the result of a low measurement of 33.8 degrees and a high measurement of 35.8 degrees and the average measurement stated on the lab report would still be 34.9 degrees which is why it is important to look beyond the average measurements stated on the diamond grading report and insist on a more extensive computerized proportions analysis when buying a round brilliant ideal cut diamond.  Large variances in these measurements often show up as inconsistencies in the pattern of light return within the Ideal Scope and ASET Scope images. However, it can be difficult to ascertain without a great deal of experience in terms of knowing exactly what to look for within these images.

This Brian Gavin Blue Diamond graded by the AGSL as weighing 1.288 carats, VS-2 clarity, I color with strong blue fluorescence was actually the first diamond which caught my attention when I looked over the initial results of my search. That’s because the I color and VS-2 clarity offset is quite desirable in terms of price and helps to maximize size. However, it is on reserve, but I’m wondering whether you happened to put it on hold between the time you sent my your inquiry and now. In which case, congratulations are in order because it looks like a beautiful diamond.

As a matter of fact, it definitely falls within the parameters of my selection criteria!   Here again, the inclusions are diamond crystals and needle-shaped diamond crystals. The diamond received an overall cut grade of AGS Ideal 0 on the Platinum Light Performance grading platform. And the spread between the high and low measurements for the average crown and pavilion angle is minimal.

There were additional options currently available within the Brian Gavin Blue collection. However, these two diamonds are the ones that specifically caught my attention.  I hope that this helps you with your diamond quest Theresa, feel free to contact me if you have additional questions or leave a comment below and I will respond to it.  Thank you.

About the Author

Dive deep into the glittering world of diamonds with Todd Gray, the CEO of Gray Matter Development, LLC. Todd has 35+ years of experience as a diamond buyer and trade consultant. He ghostwrites content for several online vendors and is an avid Freediver, currently exploring the Cenotes of Yucatan, Mexico. Dive into brilliance with Todd Gray!