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Roger Weller, geology instructor

Larissa Diamante Thurman

Physical Geology
Spring 2005

Diamonds: From Rough Rocks to Glamorous Gems

            Generally, the only thing a materialistic woman cares about is the size of the diamond on her hand, and how green it makes everyone else in the room. Is it bigger, flashier, and shinier than everyone else’s? Most importantly, is it the most expensive rock in the room? She gives little regard to the fact it may have taken hours of care and craftsmanship to construct such a thing. It took consideration of the shape of the natural diamond to determine which cut would fit it best, or which cut would cause the least amount of diamond to be lost. It took time, good eyes, special tools, and skill. She does not consider the diamond she is flaunting to be a masterpiece.

            In order to process a diamond, one must first know where to look and what they are looking for. “The main diamond bearing rocks are kimberlite, eclogite, and lamproite. Diamonds can be formed going down towards the mantle of the earth (subduction), going up towards the surface (obduction) and on impact (meteorites). Diamond crystalline shapes are numerous, the principal ones being octahedrons, cubes, dodecahedrons, rhombododecahedrons and trioctahedrons.” (Diamants Info)

Rough diamond shapes














                                                                 (Diamants Info)


Rough diamonds, like the ones shown above, are translucent crystals with little luster and very much resemble a chip of broken glass. In order for them to be of gem grade, they must be cut into shape and polished facet by facet. In the early days, this was not an easy task, or even half as simple as it is today. “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, 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.”(Epstein) After this, the diamond would undergo a process known then as bruting. In this process, the diamond was placed in a dop, an egg shaped cup made of tin, where the cutter attempted to remove any imperfections by striking it with another diamond.

            The abovementioned primitive process was used until the end of the fifteenth century, when a Jewish diamond cutter named Lodewyk van Berken invented the scaif, a polishing wheel saturated with a mixture of olive oil and diamond dust. With this invention, the diamond was clamped in a dop and ground against the whirling scaif, allowing the diamond to be cut at the desired angle and symmetrically polish all the facets of the diamond.

            Today, there are many ways to cut and polish diamonds most common being a five step process consisting of cleaving, sawing, bruting, cross working, and brillianteering. As demonstrated above, it took many years of trial and a “there has to be a better way to do this” style of thinking in order for this process to be as efficient as it is today.

Not all rough diamonds needs to be cleaved or sawed, as some are well formed and ready to be cut. In the first step of the process, cleaving, the diamond is placed in a quick-drying cement where a sharp groove is then carved in it using another diamond or a laser along the plane of weakness, in order to remove any impurities or irregularities. A steel blade is placed in the groove and a sharp blow to the blade splits the stone. The diamond is then removed from the cement.


In sawing, the second step of the diamond’s transformation, a diamond saw like the one above is used to cut against the cleavage plain. Much like the scaif, the diamond saw is a circular steel blade lubricated continually with oil and diamond powder, allowing 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. The saw requires about one-tenth carat of diamond dust for every carat of diamond sawed through.”

“Bruting is performed only for diamonds that are to be finished as round, brilliant stones. The diamond is placed in a lathe, and another diamond in the lathe is rubbed against it to create the rough finish of the girdle. (Diamants Info)” This is the third step in a diamond’s transformation.

The fourth step, cross working, lays the foundation of the diamond and follows instructions to obtain the optimum value for the finished product. At this point, a decision may be made to improve the quality of the finished product by making smaller diamonds. The work is done on a polishing disc driven by an electric motor. The disc is covered with diamond powder. The diamond is held in a clamp and the facets are polished one by one. Crossworkers polish eighteen facets to very stringent measurements and angles.

Brillianteering, the fifth and final step in the diamond process, “cuts and polishes an extra forty facets onto the previously polished facets to create a round brilliant cut diamond with fifty-eight facets unlocking the full brilliance and fire of light being reflected by the polished diamond. (Diamants Info)”

            When a rich woman is flaunting the diamond her husband old enough to be her grandfather recently bought, she probably could not tell you how many steps are in the diamond process or what tools were used to shape hers. Then again, neither can anyone else, except an expert. Much of the workload has been reduced by introducing complex automated beings to substitute for humans in tasks such as polishing. The process of transforming a diamond from a rough rock to a glamorous gem has been modified in the past and will probably continue to undergo change until the process is either perfected or completely performed with the use of robotics and laser technology. The techniques may be unknown and of little concern to her and the others in the room. All anyone cares about is the shiny scrap, which through this process and many skilled hands, has literally been carved and shaped into a masterpiece.


Work Cited

Epstein, Edward Jay. The Diamond Invention. 20 April 2005.

Diamants Infos. January 2005. 20 April 2005.
Fumeilong Import & Export Co., Ltd. April 2005. 20 April 2005.

Diamonds, their History and how to Ensure You are Getting What You Paid For. Mark, Benjamin. 20 April 2005. diamond.html