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How diamonds are actually cut

Most people know that the diamonds they see inside a jewellery store look nothing like what was pulled out of the mine weeks, months, or years before. There’s a complex process that occurs between the stone’s retrieval from the Earth and the brilliant finished product that rests in a jeweller’s case.

But, what exactly is involved in this process of diamond cutting? How are diamonds transformed from rough, shapeless blobs into shiny, beautifully shaped cuts that will serve as a focal point on a stunning piece of jewellery?



Before a diamond is cut, considerable planning goes into just how the gem will be shaped. Expert diamond cutters evaluate the rough to determine which cut, or shape, is best suited for the stone. The goal is to create a finished product that maximises the rough and leads to the least amount of waste. A special machine, called a Sarin, is used to gather the stone’s exact measurements. These figures are then input into computer software that creates a 3D rendering of the diamond that helps the cutter determine the best possible cut.


Cleaving and sawing

Once a plan has been formulated that will take advantage of most of the rough, the diamond is cleaved. During this stage, the diamond cutter uses special equipment to split the diamond at its weakest point into more workable pieces. Sometimes, diamonds must be sawed if there is no plane of weakness where they can be cleaved. Because diamonds are the hardest natural material on Earth, only other diamonds can cut them. Diamond-bladed edges are used on the equipment to make the cuts. In some cases, special lasers may be used to assist in this process.



Bruiting, also known as girdling, occurs next in the cutting process. This step involves shaping the diamonds in round pieces that will undergo further shaping and polishing later on. Bruiting is performed by placing two cleaved stones on opposite sides of a lathe, or spinning axle. The diamonds are then turned in opposite directions, grinding against each other with each revolution to create the desired rounded shape.



After bruting, the diamond’s facets are carefully formed during the polishing stage. A diamond polishing wheel is used to smooth the stone into the various facets and create the flat and reflective surfaces of the gem. A coarse diamond powder is used during this process to give the stone its final polished appearance.



The final stage of diamond cutting involves no cutting at all. This is the inspection stage, where the finished product is evaluated to ensure it meets the manufacturer’s specifications. If it doesn’t, then it’s back to the polishing wheel for touch-up work. Once the diamond is approved, it is sent to a gemological lab where it is graded and assigned value. From there, the stone continues its journey to a jeweller, where it will ultimately end up as a ring, earring, necklace, bracelet or another piece of jewellery that someone will choose to treasure for years to come.

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