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How Diamonds Are Cut

Diamond cutting is the art, skill and, increasingly, science of changing a diamond from a rough stone into a faceted gem. Diamond cutting requires specialized knowledge, tools, equipment, and techniques because of its extreme hardness.

Cut has two meanings in relation to diamonds. The first is the shape: round, oval and so on. The second relates to the specific quality of cut within the shape, and the quality and price will vary greatly based on the cut quality. Since diamonds are very hard to cut, special diamond bladed edges are used to cut them.

The process of how diamonds are cut includes these steps; planning, cleaving or sawing, bruting, polishing, and final inspection.

Planning - How Diamonds are Cut

Diamond manufacturers analyze rough diamonds from an economic perspective, with two objectives steering decisions made about how a faceted diamond will be cut. The first objective is that of maximum return on investment for the piece of rough diamond. The second is how quickly the finished diamond can be sold. Scanning devices are used to get 3-dimensional computer models of the rough stone. Also, inclusions are photographed and placed on the 3D model, which is then used to find an optimal way to cut the stone. How diamonds are cut is becoming an extremely advanced process.

Maximizing Value - How Diamonds Are Cut

The process of maximizing the value of finished diamonds, from a rough diamond into a polished gemstone, is both an art and a science. The choice of how diamonds are cut is influenced by many factors. Market factors include the exponential increase in value of diamonds as weight increases, referred to as weight retention, and the popularity of certain shapes amongst consumers. Physical factors determining how diamonds are cut include the original shape of the rough stone, and location of the inclusions and flaws to be eliminated.

Weight Retention

The weight retention analysis studies the rough diamond to find the best combination of finished stones as it relates to per carat value.

How diamonds are cut always results in a dramatic loss of weight; rarely is it less than 50%. Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the weight.

Color Retention - How Diamonds Are Cut

In colored diamonds, how diamonds are cut can influence the color grade of the diamond, thereby raising its value. Certain cut shapes are used to intensify the color of the diamond. The radiant cut is an example of this type of cut.

Turnaround Minimization - How Diamonds Are Cut

The other consideration of in how diamonds are cut is how quickly a diamond will sell. This consideration is often unique to the type of manufacturer. While a certain cutting plan may yield a better value, a different plan may yield diamonds that will sell sooner, and thereby returning the investment sooner.

Cleaving or Sawing - How Diamonds Are Cut

Cleaving is the separation of a piece of diamond rough into separate pieces, to be finished as separate gems.

Sawing is the usage of a diamond saw or laser to cut the diamond rough into separate pieces.

Bruting - How Diamonds Are Cut

Bruting is the process whereby two diamonds are set onto spinning axles turning in opposite directions, which are then set to grind against each other to shape each diamond into a round shape. This can also be known as girdling.

Polishing

Polishing is the name given to process whereby the facets are cut onto the diamond and final polishing is performed. The process takes the steps blocking, faceting, and polishing.

Final Inspection

The final stage of how diamonds are cut involves thoroughly cleaning the diamond in acids, and examining the diamond to see whether it meets the quality standards of the manufacturer.

The Process of How Diamonds Are Cut

It is possible only because the hardness of diamond varies widely according to the direction in which one is trying to cut or grind.

The process of how diamonds are cut, such as the simplified round brilliant cut, includes the following stages:

Sawing the rough stone.
Table setting where one facet is created. The table facet is then used to attach the stone into a dop.
Bruting the girdle.
Blocking 4 main pavilion facets.
Transferring to another dop. This is done to rotate the stone.
Blocking 4 main crown facets.
Cutting and polishing all pavilion facets.
Transferring to another dop.
Cutting and polishing all crown facets.

This is just one method of how diamonds are cut, although a fairly common way of creating a round brilliant cut. The actual process of how diamonds are cut also includes many more stages depending on the size and quality of the rough diamond. For example, bigger stones are first scanned to get the 3-dimensional shape, which is then used to find the optimal usage. The scanning may be repeated after each stage and bruting may be done in several steps, each bringing the girdle closer to the final shape.

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