Chapter 4

While we have covered all the positive aspects regarding the information we can attain from reflectors, this article would not be properly balanced if we did not cover the weakness of this technology as well.  As a sort of techie guru, regarding those involving diamonds, we deem it our responsibility to also demonstrate the pitfalls of placing too much emphasis upon one particular technology and how it relates to diamond appearance. What is perhaps one of the most obvious we have discovered over the course of time is the reflectors inability to determine light performance in some of the more common lighting environments, particularly those that contribute to brightness.

Within diamond, we have mentioned above how slope angles cut to a steep/deep combination of angles contributes to too much light leakage.  One of the great strengths of reflectors then is determining when too much leakage exists in a diamond, thus contributing to an appearance that is not so bright.

Here is a dynamic graphic demonstrating the appearance of this diamond in the office lighting environment next to the other ideal H&A used in the above illustrations.

	1.10ct G VS2 H&A Ideal	1.01ct I SI2 non-ideal
Static Image
Dynamic Image

Here is photograph taken under GIA's DiamondDock of the same comparison. The daylighting excellently mimics real world observation and the difference is quite obvious.

You can see the decrease in brightness as this type of diamond takes on a darker appearance in this lighting environment which is pretty common.  So when it comes to weeding out diamonds with steep/deep angles, which contribute to darkness (the decrease in brightness); reflectors are GREAT for weeding those combinations out.  That is a positive.

However, not all steep/deep combinations are bad and there are instances where they can even be brighter than diamonds with what appear to be better reflector images.  Instead  of posting it here I refer you to our case study on the GIA Excellent Steep/Deep vs a diamond with a solid reflector image.  For convenience, this was the comparison and here is the link to this case study.  It proves to be a VERY interesting read.

DiamXray Analysis
GIA Excellent	AGS Ideal

One area in particular where reflectors suffer is in shallow angled diamonds.

We generally do not purchase shallow angled diamonds for inventory but we do have some scans upon which we can make evaluations on and make comparative analysis with via the virtual models since they closely correlate to what we observe in our lab.

Here's the image, resulting from a scan which shows an excellent reflector image.

Now compare this diamonds view in the same lighting environment as above.  The shallow angled combination actually appears darker or just as dark than the steep/deep combination, once again, contributing to the decrease in brightness.

In fairness, a stone with the above characteristics does appear bright in certain lighting environments like spot lighting and strong overhead lighting but in more common lighting environments which flatter brightness, this stone suffers.  Interestingly, the DiamCalc software concurs with this decrease in brightness as well.  Note the scores in "Light Return" as well as the magified images.

Here is another stone with what appears to be an incredible reflector image.

Here is a photograph taken under GIA's Diamond Dock (an instrument created by GIA specifically for the purpose of observing the optical metrics of brightness, fire & scintillation). The above stone, while displaying superior craftsmanship in optical symmetry takes on an unusually darker appearance when viewed  in common lighting conditions.  The FireScope image above is the diamond on the right in the below photograph.  A major contributing factor to this increase in darkness is because of something called a painted girdle.  You can read more indepth about this here.

Not all shallow angled combos are bad stones though and when comparing a shallow angled stone next to steep/deep angled diamond the shallower stone will generally always appear brighter.

Here are 2 DiamXray images, one of a shallow/shallow next to a steep/deep and the resultant view under GIA's Diamond Dock.

The shallow/shallow on the left is a brighter stone than the steep/deep on the right however there is a certain darkness in both stones that disqualify them from being Ideal/Excellent from either AGS or GIA.

The "arrows" or pavilion mains take on a darkness that is noticeable and unavoidable in many lighting environments and contributes to unwanted darkness.

So in short, while reflectors are excellent devices for weeding out many steep/deep angle combinations they don't always give an accurate depiction of how the diamond may appear in everyday viewing conditions particularly with shallow angled combinations. Even with stones that appear to have what some may consider "great" reflector images.  Our very simple advice is this.  If  you are consulting this information in the consideration of the purchase of a diamond BE SURE to realize and understand the pitfalls.