The Brilliance Scope Analyzer is a tool that purports to return values for white light, color light and scintillation in a diamond using an imaging spectrophotometer in a controlled lighting environment.
The attractive quality of this machine is the consumer-friendly report it produces: The results page includes colorized photos and simply stated values. It is a tool suited for jewelers looking to quantify diamond beauty on paper in a way that the casual shopper may easily comprehend.
After testing this device we feel that it can be useful for separation of good light return versus poor light return over a range of average to good cut quality. However, when making comparisons between equivalent makes of the finest precision-cut diamonds we find the results spurious and inconsistent. Our research has identified fundamental issues with the aesthetic relevancy and analytic accuracy of what Brilliance Scope purports to measure.
Summarily, we feel our customers are not well served with Brilliance Scope data for four far-reaching reasons:
1. What it reports is aesthetically irrelevant.
2. What it reports is analytically inaccurate.
3. The inaccuracies in the reports are deceptive to consumers.
4. Even if readings were accurate or relevant, the admitted error of +/-5% makes its use as a comparative tool impossible.
Colleagues and consumers interested in our rationale can find a synopsis of conclusions, below.
1. AESTHETIC IRRELEVANCY
Unlike Sarin, which measures proportions, an Ideal Scope image that shows light leakage or a Hearts & Arrows viewer which shows physical symmetry, the Brilliance Scope tries to evaluate what your eyes can already see. However, no machine can perceive diamond beauty as well as the human eye. Issues of subjectivity and environment prevent Brilliance Scope from providing any realistic correlations.
1a. IRRELEVANCY DUE TO SUBJECTIVITY
Brilliance Scope attempts to assign a value to beauty, but human taste is subjective. Even if BrillianceScope is useful for separating high and low performers of average cut it cannot make judgments of taste. One diamond scoring slightly higher or lower than another cannot be termed as less or more beautiful, since humans see beauty differently. “Devices that measure light and evaluate a diamonds light responses attempt to give an objective result for the subjective way human eyes and the brain perceive diamonds.” – Sergey Sivovolenko (OctoNus, Moscow, Russia)
Generations of diamond cutters have worked to discover and refine several types of diamond beauty to suit humanity’s broad palate. A sudden mechanical interpretation of beauty is not acceptable as a replacement for the many variations in taste among humans who appreciate beauty at the highest level.
1b. IRRELEVANCY DUE TO ENVIRONMENT
Brilliance Scope attempts to measure in divided, mechanical terms what humans see together in nature. It uses lighting conditions under which diamonds are never viewed to calculate pixels and return separate numbers for qualities of beauty that are never viewed separately.
“To be meaningful, measurements of diamond beauty should be made in the typical illumination circumstances in which human judgment of that beauty is made. Measurements of beauty in atypical lighting can give high scores to cuts that have lower scores in typical illumination.” (Michael Cowing - “Describing Diamond Beauty”)
Brilliance and fire work in tandem to create the “life” of a diamond’s beauty. It is erroneous to separate them. Moreover, Brilliance Scope does not account for the contrast quality of brilliance in its measurements, nor does it use many small (distant) light sources so it cannot possibly evaluate scintillation in relevant or accurate terms.
2. SCIENTIFIC INACCURACY
Brilliance, fire and contrast dictated by light source(s), environment and even the viewer’s presence in the diamond’s panorama of illumination all work together to create the scintillation aspect of a diamond’s beauty when that diamond undergoes movement. Brilliance Scope cannot account for the many variables of the contrast aspect of brilliance, nor does the diamond being measured undergo movement. Therefore it has no chance of evaluating scintillation in relevant or accurate terms.
2a. INACCURACY DUE TO LACK OF DIAMOND MOVEMENT
Scintillation is a “quality” word used to describe diamond sparkle resulting from dynamic movement. A human observes scintillation when the diamond is moved back and forth. Sparkle occurs as different facets reflect light from various sources through the crown to the observer’s eyes as the diamond moves. Tolkowsky and others referred to this quality of light return as the “life” of the diamond. Today we call it scintillation or sparkle.
BrillianceScope cannot measure scintillation as the human eye sees it because the diamond is stationary while measured. Attempting to vary light sources instead of moving the diamond is comparable to asking a shopper to hold the diamond still relative to his/her eyes and jump up and down to vary how light is reflected through the crown.
Any meaningful measurement of scintillation would entail measuring white light and colored flashes coming through all of the crown facets over an accepted range of tilt (typically 30 degrees). This would require a separate measurement coefficient for the table, 16 star and bezel facets and 16 upper girdle facets. These coefficients would then need to be multiplied by all degrees of tilt. Of course, this would be a very simple starting point, as it does not take into account indexing, range of light sources, range of viewer, intensity of light, and especially contrast qualities of brilliance:
2b. INACCURACY DUE TO LACK OF CONTRAST BRILLIANCE
There is a definition of what we perceive with scintillation known as the contrast quality of brilliance (see Michael Cowing’s studies on contrast brilliance). In short, contrast brilliance is the diamond’s “static contrast,” whereas scintillation is “dynamic contrast” due to movement. Contrast brilliance is one frame or snapshot of the moving picture of scintillation. The change in contrast brilliance from one moment to the next with movement is scintillation. Mathematicians would recognize scintillation as the partial derivative of contrast brilliance with respect to movement.
Any assessment of contrast brilliance (and therefore scintillation) must take into account illumination and viewing conditions, as well as the physical presence of the viewer in the diamond’s panorama of illumination. Not only does Brilliance Scope fail to account for viewer and environment, its measurements are made in unnatural, atypical illumination circumstances (also addressed in 1b, above).
2c. INACCURACIES IN MEASURE
B2. Deceptive Returns
If Brilliance Scope is not measuring scintillation when the spectrophotometer is firing, what is it measuring? The following is information we strongly feel must be voiced about why BS gives deceptive readings for longer lower girdle facets, and the future of these diamonds in the 2005 GIA and AGS cut-grading systems.
LOWER GIRDLE FACETS
Our cut team understands why Brilliance Scope returns high “scintillation” values for stones with long lower girdle facets. We also understand why those returns are deceptive. As the percentage of the lower girdle facets increases the pavilion mains become thinner. Up to a certain percentage this may increase the brilliance of the diamond, but after 80% proper dispersal of light is compromised:
(please see this link for a diagram of diamond parts)
The pavilion mains are the mirrors of the diamond. They are the engines that drive light return. To acquire maximum efficiency, aesthetic spread and beauty within a diamond those mains are of paramount importance. The harmonious relationship between the mains and lower girdle facets is crucial. By increasing the lower girdle facets and thinning the mains you more narrowly focus light return, reducing dispersal and the contrast quality of brilliance within the stone.
Bias: BrillianceScope’s particular lighting scheme tends to assign higher scores to one type of facet arrangement. In our experience this arrangement does not result in a character of beauty with optimum visual balance. It has been widely observed that BS overlooks combinations of facet construction that may be considered equally as beautiful as its more “preferred” arrangements. It attempts to assign a value to beauty, but human taste is subjective. One diamond scoring slightly higher or lower than another cannot be termed as less or more beautiful, since humans see beauty differently. Generations of diamond cutters have worked to discover and refine several types of diamond beauty to suit humanity’s broad palate. A sudden mechanical interpretation of beauty is not acceptable as a replacement for the many variations in taste among humans who appreciate beauty at the highest level.
The reason “Scintillation” scores on BS are higher on diamonds with thin pavilions is because the light becomes more needle-like and concentrated. However, there is not increased light as BS would have you believe. As a matter of fact, the inner beauty (dispersion of white light into spectral colors) of the diamond is reduced in favor of a narrowly focused needle of returning white light. This is most tangible in soft lighting conditions, where “narrow focus” of thinner mains causes the diamond to suffer. Diamonds with thinner mains (lower girdle facets >80%) do not perform as well in soft light.
IS “BRILLIANCE THE ENEMY OF FIRE?”
No. Neither is fire the enemy of brilliance. However, the BS says differently.
Brilliance is a return of white light. Dispersion is the breaking-up of white light into spectral colors. Fire is the suite of colored flashes (chromatic flares) one sees within the diamond. The finest diamonds achieve a harmony of both brilliance and fire.
All diamonds have the same dispersion value (.044, which is one of the highest for any natural, transparent gemstone). Therefore, the amount of fire observed in a diamond is dependent on facet construction as much or more than lighting conditions. The cut will determine how much brilliance you see, how much fire you see and whether you can see both in the same gem.
Diamonds can be and are purposely cut to return more brilliance than fire (simply put: lower girdle facets >80%). Diamonds can be and are purposely cut to return more fire than brilliance (simply put: no light leakage and very thick pavilion mains). And of course, diamonds can be cut to unify and maximize brilliance and fire (simply put: true hearts and proportionate mains).
Unfortunately, the BS rewards brilliance over fire. This is why some of the best cut and well-balanced diamonds do not stand up to diamonds with over-long lower girdle facets on BS: It favors the “needles” of thin white light, even if the diamond is not ideally balanced.
Q. Where did the term ”Fire” as it relates to a diamond originate?
A. It referred literally to the reflection of “fire” (lantern, torch, etc.) in a diamond. Marcel Tolkowsky viewed diamonds under gas lanterns. An important aspect of the quality of light return is the dispersion of light into spectral colors, which are seen as fire.
Old European cuts and old Mine cuts had much shorter lower girdle halves: 72-75%, sometimes even shorter. Why? Because even in pre-Tolkowsky days the cutters knew this was the way to maximize spread of light dispersal inside the diamond. They cut by the gas lantern. The best diamonds robustly returned maximum fire under those conditions. They still do today.
Diamonds producing what has traditionally been considered the “best” light return have lower girdle halves <80%. Companies like Whiteflash (ACA) and Richard Von Sternberg (8*) still respect that proportion – which leads me to the next item:
CONSUMER BEWARE, PART 1
I am about to pull back the curtain on a controversial piece of truth-in-trade: Some cutters have discovered they can “max out” those scintillation returns on BrillianceScope by lengthening lower girdle facets to narrow and focus light return. Their over-thin pavilions return those ”needles” of light in great concentration and the machine rewards that with high numbers. This is like twisting a nozzle on a garden hose to acquire a thinner stream. There is not more water, it’s just more concentrated and appears stronger than it really is.
HOW TO TELL WHETHER LOWER GIRDLE FACETS ARE TOO LONG
We will assume that a stone cut for the Hearts & Arrows effect will have correct indexing and flat facets. Even if this is the case, stones with lower girdle facets of more than 80% will have splits/clefts in the Vs of the hearts (we call them “split hearts”). These are the hearts being rewarded by BrillianceScope. We do not believe this is a good thing. Those split hearts are an indication that the lower girdle halves have been made so long that the pavilion mains cannot achieve maximum light dispersal within the stone.
Hearts with lower girdle facets at 78%, 80% and 82%
A harmonious marriage of proportions between pavilion mains and lower girdle facets results in true hearts. These hearts have no splits in the cleft and are married to the eight pavilion arrowheads (no dead space between hearts and the pavilion arrowheads). These robust hearts indicate that the pavilions are dispersing light with maximum effect.
In A1, A2 and A3, the heart is well defined, the gap between the arrow head is distinct and clear, and the split at A3 is minimal versus F1, F2 and especially F3.
CONSUMER BEWARE, PART 2
Our sources believe that GIA’s new cut standards will reflect what has been presented in this document. They will reinforce the importance of lower girdle facets being 80% or less. There is a distinct likelihood that GIA will downgrade many diamonds with lower girdle facets over 80%. Additionally we are consulting with AGS. Diamonds with lower girdle facets >80% may be in trouble in their new system as well.
This means that if you bought a hearts & arrows diamond having lower girdle facets greater than 80% it could be DOWNGRADED a FULL GRADE if you ever have it resubmitted.
At the Basel show, before the International Cut Conference in Moscow, GIA advised people of what was going to happen in the cut grade system. That's when they said lower girdle halves longer than 80% would be downgraded. Garry Holloway alluded to this on PS before. Here is a photo from the GIA presentation:
The BrillianceScope, which rewards long lower girdle halves, is giving higher results for diamonds which may not be considered the best in GIA and AGS cut grade systems when the new cut standards are released.
This is a serious issue for BrillianceScope pundits and consumers alike. How will the people who purchased diamonds with split hearts react when they discover their diamond is now worth less, though they purchased it because of high BS returns?
Worse – what if BS returns caused a consumer to pass up a diamond with lower girdle facets <80% which will remain an ideal cut under the new system?
POST #3: GOING EVEN DEEPER: FACET “YAW”
Here is something which may pique the interest of purists: “Hot spots” talked about in BS reports can be explained by and correlated to facet “yaw” - caused by mere imprecision and “cheating” of a facet (which is not actually flat). This occurs when a facet face is polished in a direction from off-center. The face will not be flat, because the starting point (edge) is ground (polished) away “up” until the facet reaches the other side. The facet begins to yaw: One end is deeper than the other, therefore the facet is not flat anymore.
As we know, it takes a minimum of two pavilion facets, two lower girdle facets and one star facet to create the heart shape (two pavilion facets create 1 heart and 2 single sides of the next heart and so on until all the hearts are complete).
“Split hearts,” mentioned previously, are caused by lower girdle halves >80%. Though they cause a problem with light return, they can still be symmetrical. However, “yaw” sends light in unpredictable places. The result of “yaw” is poorly formed, distorted hearts, indicating a facet which is not flat and is not aligned properly with it’s opposite.
The simplest method to observe the error of “yaw” is by viewing optical symmetry with a H&A viewer.
Left: Examples of “Split Hearts.” Right: Examples of hearts with “Facet Yaw.”
CONSUMER BEWARE, PART 3
Even if a lab grades symmetry Ex/Ideal, it is only grading meet point symmetry, not overall physical symmetry. To judge a diamond's physical symmetry (large divergence of the angles, no yaw to the facets, flatness, each mirror aligning perfectly) we view its optical symmetry with the Hearts & Arrows viewer.
That being said, “hot spots” such as Rhino mentions on his BS readings can be explained if a pavilion facet has “yaw” relative to it’s opposite. The misalignment results in a focused beam of concentrated light. That brighter little shine on the machine is being read as being brighter, but that's a false reading. It’s just a spike which the BS sees. It has been termed it a “hot spot,” when it’s not truly “hot,” it’s just another manifestation of less-precise cutting.
The Holloway Cut Adviser serves the same purpose with more elegance and ease.
Choosing the “right” diamond depends on personal circumstance, philosophy and resources. No single choice is unequivocal or applicable for everyone. Diversity is humanity’s great strength and prescribes that what may be right for one does not necessarily befit another.
Two of the world’s most reputable gem labs, AGS and GIA, tested it and returned it because of its inconsistency.