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Home > Diamond News Center > Features > Articles > Diamonds

Wanted: Another Parameter for Gemological Certification


Avraham Eshed

By Shira Ami

"These stones are smiling," says founder and owner of Eshed Diam and Gemstar Avraham Eshed as he places on a table box after box of round, pear-shaped, and oval pairs of diamonds weighing around 20 carats. (That's 20 carats each stone – not for the pairs.) Eshed wants the "smile" of a diamond – of any quality – to be recorded on its gemological certificate.  He isn't speaking as a gemologist, but rather as a diamond producer and exporter who is seeking a way to increase the amount and types of diamonds in high demand in the market. "Adding another parameter of brightness or brilliance to the certificate will allow us to 'boost' stones that have lower clarity grades but a strong 'smile,'" he says.

"Anyone who's ever entered a jewelry store knows what happens: when the salesperson shows the buyer the jewelry he opens the projectors in the ceiling above the display case. He shuts them off when a salesman comes in and asks to show him stones. The wholesaler knows that the projectors put a smile on a diamond, making it shine and sparkle, which could disappear under regular neon light," Eshed explains.

"The 21st-century customer buys the stone not only because of the projectors, or because of the yellow gold settings that give I, J, and K VS1-grade stones the look of a D Flawless, but in a large part because of the gemological certificate.  Today's consumers are hungry for knowledge. They want all the information about a stone. They know what the 4Cs are and what clarity and color fit their budget. Through the gemological certificate that accompanies the gemstone they're buying, they make sure they get what they want. So it can be a big embarrassment for them when they see a certificate for a beautiful, lustrous diamond with a SI1 clarity grade compared to a certificate for a cloudy diamond with a higher clarity – VS1, for example.

"There can be a few reasons for the discrepancy between how a stone looks and its certification: one is the different scales used by various diamond labs – a stricter lab will give a stone a comparatively low grade compared to a less strict lab. A stone with a GIA clarity grade of SI2 or even I1 that causes it to sell at 30% of the market price could be graded SI1 by a more liberal lab and sell at 60% of the market price – allowing the store to offer the customer a large discount.

"Other factors that lower a stone's clarity grade are internal graining, a kind of striped effect, or strong fluorescence, either of which can cause a stone to appear cloudier. We need to 'help' stones with a grade of SI1 which look like VS1 diamonds. We can do this at the wholesale market level by adding a new parameter to the gemological certificate – brilliance."

Diamond Sparkle


rough diamond sarin
 Sarin Enlarge
 Rough Diamond

In order to understand the idea proposed by Eshed, one of the founders and owners of Sarin Technologies, we should clarify what exactly constitutes the "brilliance" whose grade he is seeking to add to the gemological certificate. Basil Watermeyer defines brilliance as "the relative amount of white light that, when it enters the stone via the table and the edges of the crown, can be reflected twice – through the pavilion edge, and again back toward the table and crown edges. The rounded angles of the round brilliant cut and the proportions are calculated to produce the maximum possible amount of total reflection. Every change in the angle or proportion will result in light 'leaking' out from beneath the girdle in the area of the pavilion."

Svedermish and Mashiach define "internal brilliance" as a full internal reflection of light: "The light ray that penetrates a diamond enters material with a very high optical density and is therefore slowed to a speed of 120-124 km/sec compared to 300,000 km/sec, the speed of light in the air. At such a low speed the light ray tends to break on the diamond's back surfaces that are in the pavilion and not bounce back out of the stone. Only certain angles allow light to bounce back and only if the angle of the cut allows it. The cut of a diamond is angled so that the light that enters a diamond from its surface (through the crown) will reflect and bounce back out of the top of the diamond only, and not from the sides or bottom."

Eric Bruton says that "It can be said that the whiter a diamond is, the more brilliant it will be. This is correct, although many people say that a round stone in a good yellow color will be more brilliant than a white diamond. The reason for this is an optical illusion, similar to that which causes drivers to believe that yellow lights are safer in foggy condition. The illusion is the result of the mind's association of pale light with the color of the sun."

For Buyers, Too

"When I purchase an expensive stone, I first check to see if it seems brilliant to me. The brilliance of a diamond is one of the most important qualities, since it determines the first impression the diamond makes," Eshed says. "If an SI1-grade diamond 'smiles' and is bright, the consumer will prefer it to a VS1-grade dull stone. If the certificate responds to this preference, the number of stone of this kind bought by jewelry stores will go up.

"Grading brilliance will not only help to market the diamonds at the retail level but also at the level of internal trade. When I sit with a client at an exhibition, his impression depends on the lighting conditions of the place. He could say, 'The stone might have gotten a VS1 grade, but it's weak.' So I can tell him that he's mistaken because of the light, but if the certificate includes a brilliance grade, and the purchaser can see that on a scale of 1-100 the stone was graded 80 or 90 – there won't be any argument. And if I can show him a device that will confirm the certificate's grade I can make him confident in the purchase.

"We, the diamantaires, are here to provide solutions for the market. We want to return the business to what it was, not necessarily in terms of pre-crisis prices but mainly in terms of trust in our product. Grading brightness will bring us to another important marketing level in restoring the belief in diamonds in this period of recovery from the global financial crisis."


This article originally appeared in the HaYahalom magazine issue 199.

To read the latest issue of the HaYahalom magazine.

By: Shira Ami
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