Although natural diamond crystals may look like tumbled rocks, most occur as eightsided crystals that took like two pyramids held base-to-base. Almost always, a single diamond crystal will yield two finished diamonds. They may be nearly the same size, or one may be large and the other small. 

An expert cutter studies and marks the crystal to determine the absolute best yield and then gives it to a sawyer. With the help of a special vice and a paper thin rotating saw blade, the crystal is sawn into two pieces, resulting in two square pyramids. Each of these is mounted into a different vice and as the diamond is rotated, another diamond is rubbed against it until the corners are worn off and the diamond is round. 

The diamond is then given to the cutter who will polish the shiny faces onto it. He starts with the largest face at the top of the diamond, then the four main faces on the upper part, then the four on the lower part. This person makes a critical decision about the angles of the faces. He holds the ability to create a lean, lively and brilliant gem or a lumpy, lifeless and dull gem. The angles he chooses in this step will govern how light will enter, mirror and depart a diamond. Once these angles are set, the cutter continues to work his way around the diamond, polishing 33 faces on the upper half and 25 on the lower half. 

The results of the labor of different diamond cutters can be as different as the results of two artist sculptors. One may render an exquisite, seemingly alive masterpiece that delights and mesmerizes the observer. The other may end up with an unappealing, clumsy, uninteresting object. A diamond's life comes from the interaction of light on its windows and mirrors. The placement and smoothness of those surfaces determines its ultimate beauty.