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Have you ever wondered how diamond roughs are cut and polished? For those of you who do not know, the diamonds you see in jewellery are not how diamonds are naturally found in the earth, nor grown in the lab. All diamonds start out as a diamond rough which is a shapeless, non shiny object. And today we will find out how we turn something like that, into the shiny faceted diamond we are all so familiar with. Don’t worry, this isn’t one of those articles like learning how chicken nuggets are made where you won’t want to eat nuggets for the rest of your lives; that reaction might be more applicable about the natural diamond mining industry, but that’s another story for another day.

Rough Valuation

There are a few steps to the diamond cutting process, but before any of that can start, the diamond roughs are sorted according to their carat, colour and clarity, also known as rough valuation. As the diamonds are not yet certified, this initial sorting process is only a rough gauge of the diamond’s potential specifications and value. After the roughs are sorted and well organised, the diamond cutting planning process begins.


This is an extremely important step as it sets the plan out for what diamond(s) to cut out of the rough. There is one main objective, which is to maximise the financial return on the rough. A skilled planner will be able to identify what diamonds can be cut out of the rough, taking into consideration how to yield the largest size, whilst at the same time maximising its clarity. For example, 2 high quality 0.5ct diamonds cut out of the same rough versus a poorer quality pair of 0.8ct and 0.3ct diamonds can have a higher return on investment. Traditionally, this is done via polishing out windows on the rough so you can look into the diamond to plan out the best diamonds to be cut out of the rough, but technology has taken this to the next level using a Sarin machine which plans out all the best potential diamonds that can be cut out of the specified rough.


This is sometimes combined with planning as it is also part of the process. Marking is essentially using a marker to mark out sawable planes to help with the maximisation of the diamond rough’s yield before it is cut.

Sawing or Cleaving

As the name suggests, the diamond rough is then sawn or cut according to the initial plan. Traditionally, the diamonds are cut using a physical saw, but nowadays, lasers are often used to cut the diamonds with more automated precision. The latter is a safer and faster way to achieve the optimum diamond(s) from the rough. A neodymium YAG laser (Yttrium Aluminium Garnet) is often used to cut diamonds and it utilises infrared light instead of visible light, and can cut a diamond in just 2 passes. The first pass converts a 20 micron layer of diamond into graphite which can be easily burned away in the second pass.

Sometimes, a process called cleaving can also be carried out. Cleaving is where the diamond rough is cleaved into smaller pieces via the tetrahedral plane where it is the weakest. A sharp groove is first carved into the diamond via a laser, and then a sharp blade is inserted into the groove where it is then forcefully struck to cut the rough into two. This process however cannot be carried out on a plane with no weakness; that is where you would then have to resort to sawing.


The previous steps merely separate the planned diamond from the rough.The actual shaping of the diamond comes in this next step called Bruting. Traditionally, this process is done by hand where diamonds are used to cut diamonds. For example, to get a round shape, you would spin 2 diamonds against each other so that they both cut each other into a symmetrical round shape. However, with modern technology, bruting or cutting can be done much faster and accurately using laser beams to shape the diamond. Round diamonds have to be round within a tenth of a millimetre to qualify as ideal or excellent cut diamonds, so laser cutting technology is a game changer when it comes to improving the cut quality of modern diamonds.


This is the penultimate step of cutting before you get a polished diamond. The blocker, who is the lead cutter and supervisor of the diamond from rough to finish, is then in charge of laying out the diamond into a number of sections depending on the shape being cut - 1 for the table, 8 in the pavilion and 8 in the crown. 

Brillianteering and Polishing

The remaining facets of the diamond are then added on by a brillianteer - 8 stars, 16 pavilions and 16 crown halves - to create a total of 57 facets (excluding the culet) on a typical diamond. This step is concurrent with the polishing process where each individual facet is polished via a polishing wheel coating in abrasive diamond powder.And here you have it, a polished diamond - shining, shimmering, and splendid! A lot of the work has already been modernised with technology, but many parts of the process still require a skilled professional to execute it. Just imagine how incredibly complicated it was to cut and polish something as hard as a diamond without the aid of the technology, especially since the first cut diamond dates back over 2000 years ago. Nowadays with the aid of technology and machinery, a 1ct diamond can be cut in the matter of 4-8 hours. Before that, it used to take weeks to cut the very same diamond by hand as you need to avoid overheating the diamond when cutting it which can cause your precious diamond to warp or even burn.With technology, the precision of diamond cutting has also been taken to the next level. As majority of natural diamond roughs tend to be lower in clarity with more natural inclusions, diamond cutters often have to maximise profits by opting for less than ideal cut proportions of the diamond. With lab grown diamonds, a bit more care and attention can be put into the cut proportions of the diamond, making a perfectly brilliant diamond to be more attainable. While it is important to honour and respect traditions, it is also important to look ahead at how we can improve the way things are done, both in technical and social aspects. And thus, our quest to find The Better Diamond will never end.