In its rough form, a diamond is a lusterless, translucent crystal that resembles a chip of broken glass. For it to be transformed into a jewel, it must be cut into a particular gem shape and then polished, facet by facet. When Sir Ernest Oppenheimer organized the diamond cartel, there were no machines that could cut and polish diamonds. The crucial transformation from rough stones to jewels had to be done by hand, and only a relatively few craftsmen, mainly in Antwerp and Amsterdam, possessed the necessary skills. Oppenheimer therefore set out to extend the control of the cartel to diamond cutting as well as to diamond mining. He realized that although outsiders might conceivably discover new sources of diamonds, they could not compete with De Beers unless they also had the means to cut diamonds. The art of diamond cutting was thus ingeniously incorporated into the diamond invention.

Until the late fifteenth century, diamond cutting had been a primitive business. Diamonds were first "cleaved" by placing a chisel at the stone's weakest point of molecular cohesion and striking it with a mallet. If the precise point was located on the diamond's structure, the adhesion would be so weak that the diamond could be separated with a fingernail. If pressure was applied to the wrong point, or in the wrong direction, the diamond would shatter. After the medieval cutter succeeded in cleaving the diamond into the basic shape of the desired jewel, he placed it in an egg shaped tin cup, called a dop, and attempted to remove any imperfections in it by striking it with another diamond, since only diamonds were hard enough to cut diamonds. This process, which was extremely slow and painstaking, was called bruting. Even though the medieval cutter could eventually give the stone a jewel like appearance through these methods, he was extremely limited by the natural shape of the diamond.

The situation suddenly changed at the end of the fifteenth century when a Jewish diamond cutter in Antwerp named Lodewyk van Berken invented the scaif. The scaif was simply a polishing wheel that was impregnated with a mixture of olive oil and diamond dust, but it completely revolutionized the art of diamond cutting. The rough diamond was clamped in a dop and held against this whirling disc, while the diamond dust on it ground away the diamond to the desired angle. With the scaif, it became possible to polish symmetrically all the facets of the diamond at angles that reflected the maximum amount of light. As disciples of Van Berken applied the laws of optics to these angles, they created sparkling gems that fascinated the princes and aristocrats of Europe. Charles the Bold, Duke of Normandy, became the patron of Van Berken and commissioned him to cut a 137-carat diamond, which became known as the Florentine.

Diamond cutters from all over Europe came to Antwerp to study Van Berken's methods, and orders for these light reflecting gems flowed in from all the royal courts, making Antwerp the pre-eminent diamond-cutting center in the world. At the head of the Pelikenstrasse, the street that winds through Antwerp's diamond district, is a bronze statue of Van Berken dressed in a jerkin and skull cap, with a holster full of diamond tools strapped across his waist. He holds in his right hand a diamond.

The next major innovation came in the twentieth century with the invention of the diamond saw. Cleaving diamonds, although an economic and efficient process, had limited cutters to shaping the stone according to its natural lines of cleavage. The diamond saw, a circular steel blade lubricated continually with oil and diamond powder, allowed the cutters to go against the grain of the diamond without shattering it. The diamond saw, moreover, allowed cutters to salvage jewels from badly misshapen and deformed diamonds. To be sure, sawing was a more expensive process than cleaving. It required about one-tenth carat of diamond dust for every carat of diamond sawed through. And it was also a much slower process than cleaving a diamond with a single stroke. Indeed, it took days to saw through a two-carat diamond. Despite such disadvantages, the diamond saw became t he common method of shaping diamonds in the postwar years. Since it was far easier to train workers to saw than to cleave diamonds, it quickly transformed diamond-cutting in Antwerp from an esoteric craft to a semi-mechanized machines to polish diamonds.

The final refinement of the process for cutting diamonds came in 1919 when a twenty-one-year-old mathematician named Marcel Tolkowsky calculated the formula for the ideal proportions of a cut diamond. Master cutters had achieved an inner light in diamonds by choosing angles that sacrificed some reflected light in order to get refracted light. They did this by relying mainly on intuition, trial and error, and experience. Tolkowsky's formula gave the optimum ratio between the angles of facets opposing one another in a diamond. Following this formula, a cutter would achieve the maximum refracted (or "inner") light with the least sacrifice of reflected (or outer) light. This formula led to the popularization of the so-called "brilliant cut" diamond, which had fifty-eight facets polished exactly to the tolerances of the ideal proportions.

With the reduction of diamonds to a mathematic formula, it became possible to devise semi-automatic machines to polish diamonds. In the early 1960s, a De Beers subsidiary introduced the Pieromatic diamond-cutting machines in Antwerp. Although these machines still required trained workers to guide diamonds through the polishing operation, they greatly reduced the need for master craftsmen or even long apprenticeships. According to the literature accompanying the Pieromatic machines, men could be trained to operate them in a matter of months.

As the diamond business expanded in the postwar years, Sir Ernest Oppenheimer made every effort to keep the cutting industry anchored in Antwerp. Not only was Antwerp just across the channel from England, and highly convenient to De Beers, but Sir Ernest considered it essential to maintain a special relationship with the Belgian government, which controlled the huge diamond deposits in the Congo. Under his express orders, Monty Charles provided the Antwerp diamond cutters with ample supplies of diamonds at the London sights while cutting back on supplies to their competitors.

Amsterdam, which had been a major diamond cutting center in the nineteenth century, gradually lost almost all its gem cutters to Antwerp. (Strict working conditions imposed on the Dutch diamond-cutting factories by the labor unions greatly accelerated the exodus in the prewar years.) But, despite all of De Beers' efforts, Antwerp did not achieve a monopoly on diamond cutting. The larger and more expensive diamonds were sent to be cut directly to New York, in order to avoid paying the tax on finished jewels, while the smaller diamond chips were sent to India to be polished by cheap labor. The "melees," or medium-sized diamonds, generally under a half carat in weight, tended to flow to Israeli factories. Nevertheless, Antwerp's cutters continued to receive most of the valuable diamonds and virtually all the difficult-shaped diamonds that required special skills.

To see how these diamonds were cut, I visited the Trau Freres factory in Antwerp. Founded in the nineteenth century, Trau Freres specializes almost exclusively in cutting a triangular-shaped twisted crystal known in the trade as a "macle." As Trau Freres is invited to De Beers' sights in London on a regular basis, it receives all its macles from De Beers. The factory employs about 100 workers, who receive on the average a salary and benefits of $400 a week, which makes them among the highest paid workers in Europe. Each worker was seated in front of a table cutting and polishing an individual macle.

The diamond I watched being shaped at Trau Freres started out looking like two triangles folded into one another. It took about ten hours for the craftsmen to saw it into its basic shape, which resembled a valentine heart. The heart shaped stone was then placed in a cup-like dop and rubbed against a second diamond in order to wear away the sharp and irregular edges. Finally, the craftsman began polishing the individual facets of the diamond on his whirling scaif. By the time this arduous process was completed, the diamond would have lost at least 40 percent of its original weight. This particular diamond had weighed io carats when Trau Freres received it in their box at the London sight, It cost them $4,000, or $400 per carat. The labor and interest costs on this individual diamond amounted to about $1,000. The final heart-shaped diamond that was cut weighed only 6 carats.

To break even, Trau Freres would have to sell it to a wholesaler for at least $ 5,000, or $ 837 per carat.

The thin margin of profit for specialty diamond cutters like Trau Freres depends almost entirely on the price they pay the Diamond Trading Company for the uncut diamonds in their box at the sights. If De Beers elects to raise the price even slightly or to provide them with an inferior selection of diamonds, these specialty cutters would be forced out of business. And according to at least one Antwerp specialty cutter, De Beers still uses its leverage over these cutters to prevent them from cutting diamonds from independent mines. By controlling the activities of these few cutters, De Beers makes it extremely difficult for any independent mine to sell the full range of its diamonds. Rather than forgo the profits from these poorly shaped diamonds, most potential competitors have been forced to sell their entire production to De Beers or one of its many subsidiaries. De Beers thus turned diamond cutting into an important element in its diamond invention.