Not so long ago, diamond traders believed all they needed to know about diamonds was what they could see through a loupe. Today, researchers at the Gemological Institute of America and De Beers are spending millions trying to unlock the innermost secrets of the diamond so consumers and the trade can benefit from better cuts, more accurate grades and advance warnings of gem treatments and synthetics before they slip undetected into consumers’ hands.
GIA, the foremost diamond research facility, devotes an estimated 60% of its considerable research activities to diamonds. James Shigley, who leads the research effort, says GIA’s diamond work is concentrated in four basic areas:
Identifying treatments of natural diamonds, such as clarity enhancement and color changes through irradiation.
Investigating quality grading issues, such as a recently introduced color diamond grading system.
Evaluating instruments, such as commercial grading machines, thermal diamond testers and new units that may be effective in identifying synthetic moissanite and other diamond substitutes that might fool traditional diamond testers.
Exploring differences in faceted diamond appearance in a quest for the ultimate cut. This is an enormously complicated project involving extensive computer modeling of how various diamond shapes and facet arrangements affect the way light travels through a diamond (see sidebar below).
Over the past five years, GIA and De Beers research teams have worked closely, even thoughantitrust laws bar De Beers from direct business dealings in the U.S. The big tie is a $1.5 million De Beers contribution to GIA’s research programs. This helped GIA to produce costly charts and videotapes on how to identify synthetic and fracture-filled diamonds. More money may be in the offing.
That flow of information back and forth is nearly constant, says Shigley. “I’m on the phone with their research people several times a week at least,” says Shigley. “We’ve had a great deal of interaction on many key issues, such as fracture filling and colored diamonds.”
Overall, De Beers’ gem defense program complements GIA’s research, says Martin Cooper, De Beers’ research chief. “We have a different set of skills. Most GIA researchers are gemologists while most of our staff members are physicists,” he says. Most GIA research centers on polished diamonds and gem treatments; De Beers concentrates on rough diamonds and synthetics. Here’s a closer look at what’s going on at both labs.
The overall research strategy at GIA is to be proactive so the industry can be warned of new treatments, synthetics and machines before they hit the market, says GIA President Bill Boyajian. But that’s not always easy, says Shigley, because many people who irradiate or fracture-fill diamonds don’t want GIA – or anyone else – to know how they do it. “It takes a great deal of detective work,” says Shigley. “But we can often figure out their methods and materials.”
Shigley shares De Beers’ view that gem labs are ahead of the potential threat from synthetics. This has been accomplished through joint efforts in creating and testing detection units and a wall chart showing differences between synthetics and naturals.
De Beers’ main mission, says Cooper, is to preserve consumer confidence in diamonds by creating easy-to-use devices that can spot synthetics easily. With that mission accomplished, scientists are concentrating on ensuring synthetic technology doesn’t get beyond the detectors.
These detectors work in two stages. The primary unit – called DiamondSure – is a small, relatively inexpensive machine that looks for the tell-tale spectroscopy lines present in all synthetics. However, a small percentage of naturals, especially D and E colors, may get flagged because there’s insufficient color for the machine to measure. In these cases, the unit’s display says “refer to lab.” Then the DiamondView comes into play. This machine is much more costly and sophisticated, seeking growth patterns unique to synthetics.
Cooper and Shigley are certain these two units have a handle on synthetics for the foreseeable future, but a cheap, reliable detector for fracture-filled diamonds remains out of reach.
“With synthetics, if you understand the physics involved, you can look for tell-tale differences in growth patterns,” says Chris Welbourne, a top researcher at De Beer’s high-tech research center in Maidenhead, a picturesque town about 30 miles west of London. “But fracture-filled diamonds are naturals with a very tiny part – 0.5 to 1 micron – filled with a foreign substance that makes the creation of a cheap, uncomplicated detection device unfeasible.”
For the time being, De Beers will limit its fracture-filled activities to funding GIA’s research in that area – the wall chart and a video that teaches jewelers and gemologists how to identify fracture-filled stones. “Looking for the flash effect is still the most reliable method,” says Welbourne. “The most distinctive thing about such treated diamonds is that the dispersion index of the filling is not quite the same as a diamond, and that creates the flash effect.”
Scientific criteria on cut
Meanwhile, GIA is focusing on establishing scientific criteria for diamond cut and proportion. Briefly, this research involves creating computer models of various diamond shapes and tracing how they interact with light. Shigley and Boyajian are tight-lipped on the findings thus far. Shigley does say there ultimately will be a number of cutting parameters that will yield maximum brilliance from a diamond.
One theory GIA is examining is a revision of the traditional explanation of how light travels through diamond – entering the stone, bouncing off the pavilion facets and exiting through the crown to cause scintillation and brilliance. GIA scientists are starting to believe a ray of light may bounce around the inside of the diamond many times, in many directions, before it exits the crown.
It’s still an unproven theory, says Shigley. But if it holds up, it could greatly alter common assumptions of optimum diamond proportion.
Researchers also have found a diamond’s finish plays a more important role in establishing brilliance than previously thought. “Most Ideal Cuts™ are very well-finished,” says Boyajian. “Perhaps that’s the secret of their beauty, not just their proportions.”
Another major diamond effort at GIA involves testing various lab instruments.
For example, GIA works with the Gran Colorimeter and its newer model, the Spectrophotometer, which color-grade diamonds. “We’re testing them with many, many stones to see what kind of results we get,” says Shigley.
Many questions remain about the Gran machines – chiefly whether they “see” exactly what the human eye sees. This is necessary to ensure the machines yield the same grade as GIA and other gem grading laboratories.
In addition, GIA helps De Beers to test some of its equipment to see how its works with heavy volumes of polished diamonds. “It’s one thing to test a unit with one stone, but another to see how it works over time with thousands of diamonds.”
Shigley freely acknowledges GIA’s research team may take too long for some in the trade – and even within GIA – who want instant results. But he is unapologetic. “It’s better to be thorough than wrong,” he says.
Some research institutes issue preliminary or interim findings on major projects, but Shigley says that’s difficult for GIA to do. “We’re halfway between the world of pure science and business,” he says. “Many important business decisions are based on our findings, including the prices of very costly diamonds.”
Shigley is aware the trade depends heavily on what GIA says and that putting out mistaken information or hastily drawn conclusions would undermine his lab’s credibility and cost dealers heavily.
Shigley cites the D-Z color grading system as an example, saying it’s as much a measure of diamond value as it is of diamond color.
It’s unlikely GIA gave any thought to such commercial considerations 40 years ago when it developed the D-Z system, says Shigley. Today, however, commercial implications can be as important as the science involved. “For instance, when we introduced our new colored-diamond grading system, we had to be sure to offer the trade something better and more marketable on the grading reports,” says Shigley.
Such pressures also require GIA to transform complicated scientific principles into practical, simple terms without overdoing it. “Things like our colored-diamond grading system or our ray-tracing project must be easily explained and used by the trade, but underpinned by very strong science,” says Shigley. “That’s often very difficult to do.”
De Beers research
De Beers devoted more than $5 million to diamond research last year. Projects at De Beers’ research center fall into two main areas – gem defense and diamond processing, says Cooper. The gem defense team is responsible for the synthetic
diamond detectors De Beers has placed at the ready in gem labs around the world in case man-made diamonds flood the consumer market. Welbourne, the lead scientist on the synthetic detector project, says the lab is trying to anticipate developments in synthetic diamond production to be certain DiamondSure and DiamondView offer a foolproof defense.
The synthetics come from De Beers’ Diamond Research Lab in South Africa, where techniciansconstantly change the recipes while creating gem-quality stones so the Maidenhead staff can continue to use them to test and improve the detectors.
Welbourne says the South African lab can re-create any known synthetic process in use today and has a good handle on how these processes may be changed in an effort to escape detection. “This gives us the confidence that we can stay ahead of developments in that area,” he says.
Though commercial synthetics have just now hit the market – virtually all in easily recognizable orange-yellow colors – the detectors are the culmination of a decade of research, says Welbourne.
The Maidenhead center also is devoted to improving diamond processing technology, speeding the logistics of processing millions of carats of diamonds from the mine to the dealer. This helps to move goods to market quicker and cheaper.
For example, the lab is working on improving automated sorting machines that can process millions of carats of diamonds yearly by color and clarity with speed and accuracy – particularly smaller goods, where it’s often uneconomical to pay sorters to look at them by hand.
Likewise, automated weighing machines developed at the lab process one diamond every two seconds – much faster than a human operator can. “With the volume of diamonds going through De Beers’ Central Selling Organisation, it’s very necessary that we have this,” says Cooper. Much of this technology isn’t geared for the general trade, which doesn’t need to process the same volume.
Another part of the lab concentrates on improving diamond working: sawing and cleaving by laser for its “prepared goods” sight boxes. These are rough diamonds that De Beers saws or cleaves for some sightholder clients. Even more work is required for De Beers-associated polishing plants in Namibia and Botswana. “Much of the material we send there is already sawn, bruted and tabled to reduce the skill required to get the best yield,” says Cooper. “This allows us to increase production and quality to make these factories economical.”
Because the requirements of diamond processing are so specialized, the Maidenhead center has its own engineering and computer-aided design units that can create their own equipment. Engineers design and test custom electronic circuit boards for most of their equipment and then, if necessary, send the specifications to a contractor for production.
This capability reduces development time and saves considerable money, says Cooper. The machine shop also uses computer-aided design to build and test prototype machines that eventually will be used in De Beers operations. “The emphasis here is on the practical, not the theoretical,” says Cooper.
After all the information on synthetics is ready to go, the challenge will be how to tell the industry of the findings without disrupting the market.
De Beers executives debated for months over how to introduce the synthetic diamond detectors. Some people worried that announcing the development would create consumer panic over synthetics. Others said holding back on development would allow synthetics to get into the market before De Beers could react.
GIA walks the same tightrope, says Boyajian. “Our challenge in reporting research results is to keep people informed but not alarmed,” he says. “It’s a very fine line, but thus far, we’ve all been able to walk it fairly well.”
GIA RESEARCHES CUT BUT DOESN’T PLAN TO GRADE IT
The Gemological Institute of America is working all-out to develop a scientific notion of what constitutes the best diamond proportions. But even when this information is in hand, GIA probably won’t add a cut grade to its diamond grading reports.
Some of the information eventually will be included on grading reports as a red flag for poorly made diamonds. But quantifying such information into a formal cut grade “would require oversimplifying very complex issues,” says GIA President Bill Boyajian.
It’s been nearly 80 years since Marcel Tolkowsky created the modern-day Ideal Cut™. While it proved to be a vast improvement over previous cuts, GIA researchers maintain Tolkowsky worked with incomplete information – the model he used was two-dimensional and the attempts at light tracing were inadequate.
Over the past seven years, GIA researchers, assisted by Cal Tech physicist Scott Hemphill, have run extremely sophisticated computer simulations of how light travels through a diamond to determine which proportions offer the best fire and brilliance. “It’s a challenging project because no one has ever done this before,” says Boyajian.
The key to success, he says, is keeping the project objective. That’s often difficult because of the financial and “prestige” premiums attached to the supremacy of the Tolkowsky model and Ideal Cut™ diamonds. “It’s a complicated optical and scientific issue, and its a complicated economic issue,” he says. “So many businesses are built on this issue that there’s a lot riding on it.”
For example, the American Gem Society gives its top cut grades to Ideal Cuts™. Diamond manufacturers, such as Lazare Kaplan International, New York City, have spent millions of dollars promoting such diamonds as the ultimate diamond cut. And top retailers have just started to convince an ever-growing number of consumers of the virtues of an Ideal Cut™.
Researchers at GIA don’t dispute the beauty of Ideal Cut™ diamonds. But preliminary indications show there will be
various cutting parameters that yield maximum brilliance and scintillation, says Jim Shigley, director of research at GIA.
The project to find these parameters involves creating computer models of diamonds of various shapes, proportions and facet arrangement, then testing how light interacts with the diamond considering factors such as the light source; the optical properties of diamond; the geometric relationships between the light source, the diamond and the human eye; and how the human eye works.
The model re-created a “virtual” round brilliant diamond in three dimensions. Construction of the model is technically complex but has many advantages, says Shigley, especially the ability to vary one or two proportions at a time while holding the others constant.
When the diamond parameters are established, researchers use algorithms (mathematical calculation procedures) to follow the paths of millions of rays of light within the
virtual diamond. The model also takes into account all of the physical properties of a diamond and how they interact with light to trace the multiple reflections of the rays until they are exhausted or exit the diamond.
The light tests are called ray tracing. According to Hemphill’s project notes, previous efforts using ray tracing neglected several important factors:
The three-dimensional fully faceted shape of a round brilliant, including a faceted girdle. Light travels through the diamond, bounces, disperses into various colors and leaks out in three dimensions.
The different paths taken by each color ray after the light disperses.
Tracking secondary rays until more than 99% of the energy has been lost.
The changes in the light ray that occur with each bounce off an internal surface. The amount of polarization affects the critical angle in a diamond and determines whether a ray is internally reflected or lost in leakage (polarization is the direction in which light waves vibrate in relation to the light’s source).
The most difficult challenge, says Shigley, is translating familiar and imprecise diamond terms such as brilliance, fire and scintillation into measurable, mathematical functions to establish a basis of comparison as the proportions of the virtual diamond are varied.
“We have managed to devise useful functions for evaluating brilliance and fire,” he says. Analysis of fire requires many more computations than calculating brilliance. Hemphill tested brilliance by systematically varying angles and table percentage relative to one another. He varied crown angles every degree between 20° and 40°, pavilion angles every degree between 38° and 43° and each percent for the table between 50% and 70% for a total of 2,000 calculations. Each one of these calculations is complex, tracing millions of rays of light and measuring results.
But Shigley says the results reinforce GIA’s impression that changing proportions relative to one another can yield two diamonds with equal brilliance but much different measurements. This, he says, will bolster GIA’s findings to skeptics who do not believe a virtual diamond can yield accurate test results.
These will be published in a forthcoming paper that describes the changes in “brilliance efficiency” (which is the light return through the virtual diamond’s crown as each crown angle, pavilion angle and table size is varied).
The project is continuing to add variables such as body color, finish and asymmetry of cut to determine how they affect the results. Research has found that diamond finish can be a very important factor affecting the way light enters and exits a diamond.
The computations for fire present greater challenges. Hemphill has worked for three years trying to streamline and reduce the time required for the computer to make all of the calculations. This is particularly crucial because calculations for fire take three times longer than those for brilliance.
Such complex concepts of diamond cut cannot be boiled down into simple grading terms such as “excellent,” “good” and “fair,” GIA researchers and executives agree. For this reason, coupled with opposition from the much of the diamond trade, GIA will not add a formal cut grade to its diamond reports, says GIA.
However, Boyajian says GIA reports can “flag the dogs” when the proportions of a diamond fall outside any accepted boundaries. “We can do this once we substantiate these boundaries and the trade agrees to them,” he says.