Diamond cutting is the process that takes a rough diamond and changes it into a shaped and beautiful gem. The process must be undertaken by a professional with expert knowledge, equipment and tools for the job since every single decision made will affect the outcome of profitability.
So, what are the main considerations a cutter take into account when planning to cut a diamond? The first choice to make is to decide on the shape itself; round, oval, pear etc. And secondly, the proportioning of facets and quality of the cut (i.e. symmetry and polish) are planned with computer simulations.
In this article, I’ll be showing you what really goes on behind the scenes when a plain looking rough gets transformed into a bright, shiny gem.
Did you know that almost 80% of all rough diamonds pass through different hands in the city of Antwerp, Belgium? Out of these rough stones that are traded, 92% of them will end up in India and are actually cut in the city of Surat.
This means whatever diamond you are buying in the market today has more than likely traveled around the entire globe before it reaches your hands!
Since diamonds are made of the hardest material in the world, only a diamond can be used to mechanically cut another diamond. Lasers are another alternative but their uses are largely limited to the cleaving and bruting purposes. Usually, the tools used in the workshop consist of diamond-bladed edges or discs that are lined in diamond dust.
The actual process of how diamonds are cut and polished can be broken down into five steps: planning, cleaving, bruting, polishing and inspecting.
Planning to cut a rough stone is one of the most important things to get right. While it can be a time consuming process, this is also the step that determines the final value of the finished products.
In the planning stages, the cutter will figure out the best possible shapes of the diamond in order to minimize waste and maximize the yield of the rough stone. Typically, the rough stone is mapped with a Sarin machine to generate accurate measurements.
With this data, a computer software is then used to formulate 3D models that will show the cutter the best ways to optimize the rough.
Copper disc embedded with diamond dust sawing a rough diamond.
The cleaving process is the part that involves splitting the rough into separate pieces. This will then allow the cutter to work on the pieces separately and also to utilize the rough fully.
Mechanical sawing can also be undertaken at this stage. In the case of oddly shaped roughs, the sawing process can also be undertaken with contactless cutting tools like lasers.
Mechanical bruting to form the outline of the polished diamond.
After the diamond is split, bruting is then performed to make the separated rough stones round. This is process is also known as girdling. What happens here is that two diamonds are placed on a spinning axle across each other. They will then turn in opposite directions and grind against each other to create a rough girdle finish.
A rough diamond being facetted on a polishing wheel.
Once the rounded shape of the rough is formed, the next stage is to create and form the facets of the diamond. The cutter places the rough on a rotating arm and uses a spinning wheel to polish the rough. This creates the smooth and reflective facets on the diamond.
Interestingly, this polishing procedure is further divided into 2 steps: blocking and brillianteering.
In the blocking process, 8 pavilion mains, 8 crowns, 1 culet and 1 table facet are added to make a single cut stone. The importance of this step is to create a template for the next stage.
The brillianteer will then finish up the job by adding in the remaining facets and bringing it to a total of 57 facets. He holds great responsibility as the fire and brilliance of the diamond is determined at this stage.
The last stage is the inspection process. This is where the diamond is checked to make sure it meets the specifications set out by the manufacturer. If need be, the stone would be sent back to the polishers for some touching up if it didn’t meet the quality control standards.
Once a diamond has been cut, they are usually sent to the gemological labs for a grading report to be obtained. This will not only increase the value of the diamond but will also help people buy the stone with confidence.
Take note: When buying online or via physical stores, AVOID any stones that don’t come with a reliable grading report from AGS or GIA.
Chances are, the diamond’s quality is really poor and the jeweler is banking on selling it to an unwary customer. You see, selling an uncertified diamond turns in a better profit as compared to sending the stone for grading only for it to return with a damning report.
If you are interested in picking up the craft or want to enroll yourself in a diamond cutting school, check out the following websites for more details.
American Institute of Diamond Cutting – Besides offering courses, they also sell useful textbooks for references on rough and colored diamonds.
Corlia Roberts Diamond Education College – Based in South Africa, they are one of the most recognized schools in the continent. Upon graduating with a certificate, the knowledge you had acquired will help you open doors to careers in the industry.
Harry Oppenheimer Diamond Training School – This institute is a joint project between De Beers and the Diamond Foundation of South Africa, Johannesburg. The courses offered prepare you for real life diamond cutting and skillsets to tackle problems in the industry.