How Diamonds Are Cut
Once the manufacturer has determined the desired cut, the stone is sent to a gem cutter. Gem cutters have been in existence for over 600 years. The first formal cutters guild was formed in 1375 in Nuremberg, Germany, and was known as the Diamantaire. This guild was directly responsible for the development of the various cuts we see today. When a cutter receives a rough diamond, it resembles a small piece of dull crystal. It is the cutting, faceting and polishing that allows the stones full potential to be realized.
This Process Occurs In A Few Key Steps
Step 1 : Marking
At this point the cutter marks the diamond using a computer-aided design system, the machine analyzes the stone, and then marks the surface using a very precise laser beam. Prior to the use of computers cutters would use an indian ink pen to mark the stones for cutting.
Step 2 : Sawing / Cleaving
As diamonds typically form in the shape of an octahedron, a diamond will need to be sawn or cleaved into two or more pieces for each individual diamond to be cut. This can only be done with a blade charged with diamond particles or a laser, as there is no substance harder than a diamond. A diamond is most often cut in a parallel direction to the crystal grain in order to ensure a cleaner surface, and maintain structural integrity.
Step 3 : Bruting / Girdling
Bruting involves the shaping of the base of a diamond, to give it its form. This is a process that defines the circumference of a diamond by creating a narrow edged plane separating the crown and the pavilion of the diamond, other wise know as the girdle. This is typically accomplished by setting the diamond onto a spinning axle and grinding it against another that is spinning in an opposite direction. This can be a painstaking process, and while some cutters have computer-aided systems to help complete the task, others still prefer to complete this step manually.
Step 4 : Polishing
Polishing is the process of adding facets, or flat faces to a diamond. The angles of each facet determine how light passes through a gemstone. The ideal facet is positioned at such an angle to reflect the light back into the gemstone. When faceted perfectly a stone will display an optimum balance of internal reflections (brilliance), color dispersion (dispersion), and brightly colored flashes of reflected light(scintillation).
The process of transforming a rough diamond into a polished gemstone is both an art and a science. It requires specialized knowledge, tools, equipment, and techniques. A well-cut diamond will reflect light from within itself, bringing out its true brilliance.
Read the next article: How Diamonds are Graded