The gemological institutes are guilty of denuding the diamond of the last bits of art that it had left and are leading the way to it becoming a cold technical product, says Amnon Amuel of the Caribbean Gemological Institute writing at www.israelidiamond.co.il. We must come together to stop this trend, which is closing the last space left between alienating parameters and a romantic product. The exaggerated importance the gemological laboratories assign to fluorescence and cut grade – the gemological certificate's newest grading parameter – are both responsible for the new fashion that is leading to the diamond completely losing its art and illusion.
On January 1, 2006, the Gemological Institute of America – the world's leading gemological laboratory – that it would be issuing new certificates for round D-Z colored diamonds with clarity grades from F-I3. The new certificates would bear a new grading parameter – cut grade. Other labs joined the movement. The HRD added the new grade at the beginning of 2009, as did other laboratories.
Cut grade is based on many parameters, including a diamond's brightness, fire, pattern, weight, table, facets, crown angles, girdle width, culet size, and symmetry.
To understand why the cut grade is only issued for a certain range of round stones, we must understand Snell's Law, the most important law of physics for giving a diamond a lively, scintillating appearance.
Snell's Law states that a ray of light that enters a diamond and hits a polished diamond surface at a certain angle will leave the surface at the same angle until it hits the critical angle of 24° and 26 minutes. Polishing can cause the desired refraction of light – this is done through polishing at proper angles, which guide the light ray toward the stone's crown (its table and upper facets) to produce a spectrum that will be expressed in the stone's fire and brilliance. When polishing fancy diamonds, the light ray can't be played with or manipulated as it can in round cuts. These cuts can't meet the new parameters of cut grade, and therefore do not receive one.
Fancy colored diamonds aren't part of the group that receives a cut grade, either, since the gemological laboratories acknowledge that the main purpose of cutting is to produce the optimal saturation of a stone's given color. To do so they must occasionally polish the stones at sharper or shallower angles than would otherwise be used. Such deviations improve the appearance of a colored diamond rather than detracting from it.
Moreover, cut grade is not applicable to many types of round diamonds, including older diamonds with 57 facets, which could lose receive a low cut grade and lose a significant part of their value. It would be interesting to know what would happen if the Queen of England were to send the crown jewels to be certified and receive back a certificate – doubtless in a formal ceremony – that declared the quality to be poor because the diamonds hadn't been cut according to the same proportions and symmetry accepted today.
In addition, we should note the possible damage to diamond manufacturers, traders, and investors, who are holding diamonds manufactured before 2006, when there was no cut grade.
The Stone's Brilliance
The most importance parameter in determining the best look for a diamond is its lively, scintillating performance of light (brilliance.) I will take this opportunity to make order out of the different terms used to describe the light a viewer sees when the ray of light inside the diamond leaves the table. The definition is based on the GIA's 2006 guide to cut grade:
•Brightness, Brilliance, Luster: These terms express all the reflections, interior and exterior, of the white light. The main measurements that determine the brilliance grade of a diamond are the proportions of the table and the angles of the crown and the pavilion. A large range of table proportions (52-62%), a relatively large range of crown angles (31.5-36.5°) and a only a very narrow range of pavilion angles (40.6-41.08°) can produce an attractive diamond.
•Scintillation: Scintillation has two factors – luster and pattern. Luster is the points of light that appear when the diamond, the viewer, or the light source move. Pattern is the relative size, order and contrast between light and dark areas, created due to the diamond's internal and external reflections when it is viewed through the table.
•Fire: A diamond's fire is visible as a result of the light ray hitting the crown's facet angles. Upon leaving the diamond, the light ray is refracted into a spectrum. The spectrum is so small that it appears to the human eye as a small sparkle.
Art and Precious Objects
The technical and technocratic digging into the depths of a diamond's soul is like evaluating a Picasso painting according to geometric parameters. As a gemologist and diamantaire, I am concerned that soon the day will come when gemological laboratories will set the prices of diamonds, as well. The gemological analyses have become too sophisticated, and do not account for the needs of the diamond dealers or the fact that diamond manufacturing is not only the product of calculating facet area and angles, but also – and mainly – the product of thought, imagination, and artistic vision.
Some manufacturing decisions cannot be calculated, and yet, maybe because of this, the final product will be special, beautiful, and more attractive and eye-catching.
Today's gemological institutes make independent decisions without considering those who deal with diamonds, who must, as the market dictates, send their diamonds for analysis and be answerable for every parameter or added parameters that the labs invent.
Cut grades increase expenses for the diamantaire and reduce or eliminate the illusion created for the buyer. This situation causes unnecessary damages and problems for both diamond manufacturers and sellers.
We must not let galloping technology override our knowledge and a diamond's illusion, which are the heart and soul of the industry in which we invest money, daring, initiative and no small trade infrastructures. We must put our faith in diamond manufacturers and encourage their creativity instead of shoving it to the margins.
Gemological institutes should concentrate on their real job: identifying the diamond, verifying its source and certifying its authentic data – not giving grades for production, other than grades for careful parameters, using known, accepted and exact measuring instruments, as was accepted until 2006.
