diamond cutting

What techniques are used to cut a diamond?

Diamonds exist in many different shapes, cuts and sizes, but how exactly are diamonds cut once they have been mined? What different techniques are used in this process? In the article below we’ll explain more about what diamond cutting really is and how they are cut. Additionally, we’ll reveal the different stages in the transformation from a rough diamond to a beautiful cut diamond.

What is diamond cutting?

The transformation from a rough crystal to a faceted gemstone is fascinating in its own right. Cutting a rough diamond is the key that unlocks a diamond’s potential beauty, and arguably the most important step. It takes great skill to cut a rough diamond. Due to their extremely hard substance and other specific challenges, diamond cutting requires specialised knowledge, tools, equipment and techniques.

Centuries of technological evolution have shaped the art of precision that is achievable today. By adapting computer-imaging techniques, precision measurement systems, lasers, and other modern technological equipment, manufacturers have improved their ability to cut gem diamonds in ways unimaginable before. Understanding the process reinforces the way one perceives the full value of both the diamond and its visual impact.

How are diamonds cut?

Some people might ask, “If diamond is the hardest material on Earth, then how can they be cut at all?”. A good, simple answer is that diamonds are cut using other diamonds. When it comes to the mechanism of cutting, instead of slicing down as with a knife, it is more similar to filing or grinding.

Are diamonds cut by hand or machine?

Traditionally, cutters would cut diamonds by hand with the help of different tools. Cutters can now use either a combination of machinery and manipulation, or opt for fully automated processes. Modern laser technology offers more accuracy and better outlines, resulting in better symmetry of products.

A laser cutting system can cut extremely hard materials with highest precision

What are the initial diamond cutting process stages?

Planning the cut is the first part of the process, as the goal is to transform the natural features of the crystal into the best combination of 4Cs in the finished gemstone. For most diamonds, this process progresses quickly, but that doesn’t mean it’s haphazard. Similarly to a master chess player picking the best possible sequence of moves, the cutter analyses the rough stone, evaluates the variables, and decides what steps will be taken. Sometimes this can be done by marking, in other words, drawing points directly on the crystal with ink. Scanning devices and 3-dimensional models can also be used to find an optimal way to cut the stone.

What techniques are used to cut a diamond?

Once the crystal is assessed and the cutter is committed to a blueprint, it is separated into pieces before shaping and polishing.

One way to do this is using force to split the diamond in a weak crystal direction, called cleaving. This is the simplest technique, and probably the oldest. The diamond is mounted in a dop or holder and a groove is carved along the plane (called a kerf). The cleaver then inserts a steel blade in the groove and strikes it with a controlled blow, cleanly separating the rough diamond in two parts.

Another technique used is sawing, which is the standard method used today as it allows greater control of the final shape and weight. Initially, diamond saws were simple tools made of metal wire strung on a bowed wooden frame. The invention of the rotary diamond saw improved the process speed, as it consists of an electric motor driving a circular phosphor bronze blade at about 4000 revolutions per minute. The diamond is mounted in a dop and the sawyer clamps the diamond to rest on top of the blade. The rim of the saw is charged with diamond dust, so that as the sawing continues, the blade continues to recharge itself with diamond from the crystal being cut. The saw can cut through a 1-carat rough diamond in 4 to 8 hours, but it can take much longer if it hits a knot.

In more recent laser sawing units, the diamond sits in a dop (similar to conventional sawing) on a computer-controlled platform. The cutting pattern is programmed into the computer by a technician, and progress is monitored on a screen. Once engaged, the platform moves the diamond precisely along the programmed path until complete. The high intensity beam of the laser burns through the diamond, separating it into two pieces. Even though equipment is relatively expensive and the technique results in more weight loss than mechanical sawing, some important advantages are to be considered. For instance, sawing time can be reduced by over 50%, grain pattern restrictions and inclusions are eliminated, and greater precision allows production of novelty shapes (flowers, butterflies, crescent moons, etc).

What techniques are used to shape a diamond?

After the sawing or cleaving, the next step is shaping the diamond’s girdle outline.

Bruting (sometimes referred to as girdling or rounding) is a process giving a diamond its shape. Like cleaving, it is an old but effective method that has benefitted from the application of modern technology.
For bruiting by hand, a cutter uses a stick-like instrument with dop to hold the diamond. The diamond is inserted with just one corner exposed. Two of these sticks are rubbed against each other to wear them away. In the mechanical process, two diamonds are mounted on separate lathes and spun so they brute each other at the same time.
Laser bruting is another more modern technique and works much like laser sawing.

To create the diamond’s finished look, faceting and polishing is required. There are several separate tasks involved known as blocking, cross-working, and brillianteering. All of these are performed using similar equipment. The crystal is placed onto an arm or mechanical clamp above a rotating polishing wheel. The wheel is coated with an abrasive diamond dust that smoothens the diamond as it is pressed against the wheel.

Finally, the diamond is cleaned with acids, followed by a thorough examination process for grading its cut, colour, clarity, and carat weight.

You now have a full overview of how a diamond is transformed from a rough stone to a beautifully shaped diamond. Do you have any more questions regarding our specific techniques, or are you interested in buying unique Uniglo Diamonds? Contact our team today.

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