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In-Depth
Making the Grade
How the GIA developed the diamond grading system as we know it today.
By Ettagale Blauer
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Diamond Grader in a GIA laboratory.
Photo by
Valerie Power; ©GIA.
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How white is rare white? Is it whiter than exceptional white? What do River, First Water, Jager, Top Wesselton and Cape mean when it comes to pricing a diamond? There was a time when these traditional terms were the only language the trade had to describe white diamonds.
Before the Gemological Institute of America (GIA) introduced its D to Z grading system for white diamonds in 1953, dealers worldwide used such terms to describe and value their stones. But it was a very imprecise science. One man’s Top Wesselton could be an F, while another stone with the same label was a G. Small wonder, as Beny Sofer, of New York City’s Beny Sofer Inc., says, “We used to sit in the Diamond Dealers Club and fight with each other” over grades.
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Many of those original key diamond grading terms referred to South African geography, South Africa being the principal source of diamonds from the late 1800s. Wesselton was a kimberlite pipe that produced many fine white stones and became part of Kimberley’s underground operation, dating back to 1892. Cape referred to diamonds from mines in the Cape of Good Hope province that exhibited a yellow tint. Jager came from the Jagersfontein mine that was known for its blue white diamonds, a term used to describe fluorescence. General descriptives like River and First Water referred to alluvial diamonds.
The transition from those rather vague terms began to give way to letter-grade precision in the 1940s when GIA began using a new grading system as a teaching tool, according to Tom Moses, vice president and chief laboratory officer at GIA. “Richard Liddicoat was working on this,” explains Moses. “At the time, most diamond dealers referred to colors as A, then AA, AAA, etc., Liddicoat wanted to create something that was objective. He worked with the industry to establish the increments, selecting the master stones and setting the color scale. That scale was used primarily for gemology students learning how to grade diamonds until the 1960s. By the late 1950s and early 1960s, more dealers were coming to the GIA, asking the lab to apply the D to Z grading system it was using in the classroom to their stones. The GIA’s color grading scheme was evolving into a valuable tool for dealers. If the old term River referred to any stone between D and F, they wanted to know, ‘Is my stone a D or an E or an F?’”
The GIA system, with its more user-friendly alphabet nomenclature, in time eclipsed all the diamond grading systems that came before it. A certain amount of tinkering continued through the decades as dealers and the GIA itself sought to create the fairest and most specific and well-defined system possible.
In the meantime, other organizations continued to address the grading issue in their own way and from their own perspective. In 1966, the American Gem Society (AGS) devised a numerical system in the assumption that numbers would be most scientific. Its system, which AGS restricted to its members, started at 0 — equivalent to D — and inched down in half-point increments to 2 for H and 4 for L, culminating in a final grade of 10 for grades X-Z.
In 1975, two prominent industry organizations, the World Federation of Diamond Bourses (WFDB) and the International Diamond Manufacturers’ Association (IDMA), formed the International Diamond Council. The specific purpose of the council was to develop “a set of universally accepted standards of nomenclature for polished diamonds with the international diamond trade.” But the terms the council came up with hardly served to clarify or define diamonds. It used such vague designations as exceptional white, rare white, white, slightly tinted white and so on, down to tinted color 1, which corresponded to M on the GIA scale, and tinted color 2, which encompassed everything from N to R on the GIA scale.
Some of GIA’s initial work on its grading system, which evolved over time, was carried out in conjunction with the American Gem Society (AGS) in the 1930s. This grading system stood apart from the very beginning simply by starting at D. The first letters of the alphabet, especially A, had become so tarnished and misused by that point that Liddicoat wanted the new system to start over from a clean point. No one, he felt, would misuse D, which up to that time was a color grade that meant “nearly failing” to gemology students.
The earliest version of the system, designed for exclusive use by AGS members, was used by them beginning in the early 1940s. The system was taught to jewelers by Liddicoat and other GIA instructors, including Bert Krashes and G. Robert Crowningshield. It was at this point that the D to Z system began its rise in importance.
It is critical, of course, that a universal grading system is used in a consistent, uniform environment if the results are to be accurate and dependable. Leveling the grading field was an ongoing concern for dealers who, as early as the late 1880s, were aware of the impact of surroundings on the appearance of color in a diamond.
Lighting was the first issue to resolve. Even before there was a GIA, diamantaires were advised to use “good north light” to grade diamonds only between the hours of 10 a.m. and 2 p.m., and to always conduct the grading in the same location. One of the first changes implemented by the GIA system was getting away from good north light, itself a vague and inconsistent standard. The demand for consistency only increased, as more and more people came into the trade and as jewelers’ lighting conditions naturally varied from one location to another.
Over the decades, GIA refined and improved both the viewing environment and lights used in it to create the most consistent grading situation possible. Even the useful life of the lamps had to be considered because fluorescent bulbs tend to dim long before they burn out. While the average life of a lamp is around 5,000 hours, GIA has determined the useful life to be less than half that, and the institute replaces bulbs when they have burned for just 1,800 hours.
In 1941, George M. Shipley and Liddicoat introduced the GIA colorimeter, a visual color comparison instrument, a color scale that represented grade categories, a standardized light source and viewing environment. They also offered a service to grade reference or master diamonds for AGS jewelers. This formed the basis of today’s grading standards.
As GIA was designing and refining the D to Z grading system, dealers were facing the changes from a very different perspective: What impact did these letter grades have on determining the value of their inventories? Did the system take away the value of the dealer’s eye, his judgment as to whether a stone was Wesselton or Top Wesselton?
Just ask Sofer how he decided on a diamond’s color grade. “We had samples that we submitted to GIA,” he recalls. “We had 70-, 80-, 90-pointers; we couldn’t afford bigger. This was maybe in 1974 or ’75. We would compare these to our sample stones. This is how you do it. You look at the stone, count one, two, three, then put the stone on the other side of the sample, count one, two, three, then make a decision. If you look at it for too long, if you start switching stones, you will have a whole lot of confusion.”
Sofer says the grading is complicated by the fact that “With each eye, you see differently — the right and left sides — so you take the in-between medium.” Before the GIA’s grading system came along, he says, “There were three categories: white, commercial and top silver, which referred to yellow stones. White was blue white. Commercial was the whitest, but not blue white. The new system made it easier.”
Sheldon Kwiat, president of Kwiat in New York City, recalls switching his family firm over to the D to Z system. “What the GIA system has given us is a common language. It’s very effective when discussing the color of a stone over the phone or in an email. The GIA system is very consistent as long as someone is using the terms in the right way,” he says. He further notes that “Years ago, the retailer had to rely on his supplier’s understanding of diamonds for the difference between G and H. With a standardized grading system, retailers no longer have to rely on their suppliers’ knowledge.”
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| Master Stone Set. GIA master stones are located at the highest point in their respective grade range. A diamond equal to the G master is graded a G. If it has slightly less color, it would receive a grade of F. A diamond with more color than the G master and less than the H master would receive a G grade. A diamond with less color than the E master is graded a D. A diamond with more color than the Y-Z master is graded face-up as a fancy color. Photo by Robert Weldon; © GIA. |
In addition to consistent lighting, the grading system’s consistency is dependent on the use of a master set of comparison stones. Kwiat explains that “We select certain diamonds that are at key points on the grading scale. We have nine round diamonds ranging from a low D — borderline D-E — down to a low L — borderline L-M. The vast majority of diamonds that we send to GIA, we are in agreement on.”
What happens when a stone is on the borderline? “Someone has to make a call,” Kwiat says. “Within any grading system, you always run into issues of borderline color. Diamonds don’t come in finite colors; they come in a continuum of colors. For those that fall on the border line, by and large, GIA does a very good job.”
Trying to resolve those borderline stones led to an experiment sometime in the 1970s in range grading, applying two letters to the same stone such as E-F or G-H to indicate the stone fell in that color range, according to Moses. When he joined the GIA in the mid-70s, he says, “We did range grading. In some ways, it’s easier but you cannot turn back the clock to range grading today. There is a degree of tolerances in judgment. There are still going to be boundary issues.”
Bill Boyajian, former president and a 20-year veteran of GIA, says, “The best way to lessen the problem is to be sure the master sets themselves are consistent.” Referring to the “master master” set that resides in a safe at the GIA, he adds, “All the other sets in the labs have been made off that set. Master sets used by other labs likewise have been graded against the master set of the GIA.”
Marvin Samuels of Premier Gem Corp. in New York City began as a cutter in the 1960s, a time when the dealer’s eye meant everything in evaluating very large diamonds. He recalls an exchange he had with Harry Winston in Winston’s offices at Fifth Avenue and 56th Street, which were brand new at the time. “Going back to 1964 or ’65, I started to make some big stones. I made a 23.30-carat marquise, D color. We called them blue white at that time. It wound up being difficult to sell. I used to buy white rough from Harry Winston so I walked up to him and said I wanted to swap it for a rough.
“I told him, ‘It has a certificate from the GIA.’ He said, ‘What’s that?’ I said, ‘It’s a new lab.’ He said, ‘It means nothing to me. They are buying my name, not a certificate. It will never work; it will never fly.’ He laughed at me. He said, ‘Did you pay for the certificate?’ I said, ‘Yes.’”
To Winston, experience and a keen eye were the only grading tools a diamantaire needed; he scoffed at the idea of getting a piece of paper from the lab to validate a stone. But for most of the trade, that certificate was the Good Housekeeping Seal for a diamond and it made all the difference to a young cutter like Samuels. Up to then, he says, “I couldn’t sell it to a jeweler. The GIA certificates gave cutters like us the ability to compete with Harry Winston, Van Cleef & Arpels” by providing third-party certification of a diamond’s quality. “That opened up a whole different kind of business,” says Samuels. “That helped the industry. That leveled the playing field.”
Since 1955, when GIA issued its first grading report, it has issued reports for millions of diamonds. Yet, even with the best efforts, diamond grading cannot get past the human factor — or the very nature of diamond material. Moses says, “In my own experience, I look at a stone one day and then another day, I feel it’s a different grade and this is in that boundary area. We could do a better job if we made all diamonds parallel planes. But a diamond is cut to make light bounce around and that is contrary to the visual system, the art part of what we do and what makes diamonds more spectacular and desirable. That’s part of the mystique or art side of diamonds.”
The color grading system is the ultimate referee to the never-ending question: How much is this diamond worth? When the industry values a G over an H by 20 percent more, that judgment call carries a hefty price tag. It gives the industry as well as consumers a scientific basis on which to value diamonds. The universally accepted GIA certificate is the go-to document for diamond buyers around the world. The opinion of other labs is highly regarded, particularly in Europe where Gübelin and SSEF are well known, but international buyers expect an important diamond to have a GIA certificate. Article from the Rapaport Magazine - April 2014. To subscribe click here.
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