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How Are Diamonds Cut and Polished for Engagement Rings?

Published by MarlowsDiamonds at Sep 01, 2023
How Are Diamonds Cut and Polished for Engagement Rings?

Diamonds are the shimmering centrepiece of engagement rings. Before a diamond can crown your engagement ring, it must go through a transformation from a rough stone to a glittering gem. This transformation, achieved with expert cutting and polishing, is what gives diamonds their signature radiance and allure.

In this guide, we explore how diamonds are cut and polished. We also look at the qualities of a well-cut diamond that is perfect for your engagement ring. 

How Diamonds Are Cut and Polished

Diamond cutting and polishing is the process of transforming a rough stone into a faceted diamond, ready to be set into an engagement ring. This process requires expertise and specialised equipment to ensure a brilliant result. 

We outline how diamonds are cut and polished: 

Rough Diamond Evaluation Process

Whether it is a mined or lab-grown diamond, the transformation journey of a diamond starts with an evaluation of the raw stone. 

During the evaluation process, the rough stone is scanned by a Sarine machine. This machine provides a precise 3D model of the rough diamond. 

The 3D model provides detailed insight into the diamond’s characteristics, including any inclusions and estimates of the clarity and colour. This helps to determine the optimal way to cut, shape, and facet the diamond to maximise its value and aesthetic appeal. 

Rough Diamond Cutting Process: Cleaving and Sawing

The diamond cut is one of the important elements of the four C's for diamond characterisation. To achieve a stunning diamond cut, diamond cutters will either cleave or saw the rough stone. 

Cleaving is a traditional diamond-cutting method that involves splitting a rough diamond along the diamond grain, or where there are structural weaknesses. A steel blade is placed in a sharp groove along the grain. This steel blade is then hit with a controlled blow, causing the diamond to cleanly split. 

While cleaving is still a useful method in certain circumstances, it does come with some risks. A misjudgement during this process can result in damage to the diamond or unnecessary wastage. 

Sawing involves cutting the diamond without any regard for the natural grains, offering greater flexibility for achieving specific diamond shapes. Sawing can be done with diamond-tipped saws or lasers. The sawing method allows for enhanced control and precision in diamond cutting, making it a preferred method. 

Rough Diamond Shaping Process: Bruiting or Girdling

Post cleaving or sawing, the diamond moves to the bruiting stage, also known as the girdling stage. During this stage, the diamond is shaped into the desired form that was decided during the evaluation process. 

During the bruiting process, the diamond is mounted on a lathe and its edges are ground down by another diamond. This shapes the diamond and establishes the girdle, which is the thin perimeter that divides the top (crown) and bottom (pavilion) portions of the cut stone. 

Diamond Faceting Process

Diamond facets are the angled flat surfaces on the diamond. Each facet is meticulously crafted to capture and reflect light perfectly, enhancing the diamond’s brilliance. The number of facets a diamond will have will depend on the diamond's shape and the cut quality. 

The faceting process is pivotal to the diamond's final look. The shaped diamond is placed in a specialised holding tool and run along a spinning wheel called a Scaife that is coated in diamond dust. The craftsman or machine will then create each facet by pressing the diamond against the Scaife at specific angles. 

Diamond Shining Process: Polishing

After faceting, the diamond is polished using a spinning wheel coated in fine diamond powder. This process smooths out any scratches and gives the diamond its iconic shimmer. 

Diamond Inspection Process

Once the diamond has been cut, shaped, faceted, and polished, it undergoes a final inspection. Experts will thoroughly inspect the diamond with magnifying tools to determine the diamond’s cut and polish quality. If the diamond passes this rigorous inspection, it's ready to be set into a beautiful diamond engagement ring.

Qualities of a Well-Cut Diamond

During the inspection process, experts will examine various characteristics of the diamond to determine the overall quality of the cut. 

We highlight the qualities of a diamond that has been expertly cut and polished: 


Brilliance refers to the reflection of white light that gives a diamond its signature glow. When light enters a diamond, it should bounce internally from facet to facet and then reflect out through the top of the stone. A diamond that is cut too deep or too shallow will look dull, while a well-cut diamond will sparkle with unmatched brightness. 


Fire, or dispersion, is the ability of the diamond to split white light into its spectral colours, creating a mesmerising rainbow effect. A masterfully cut diamond will exhibit vibrant flashes of red, blue, yellow, and other colours, especially under direct light.


Scintillation is about the flashes of sparkle on the diamond’s table and facets. When you move the diamond, there should be a play of light and dark areas. A good cut ensures a captivating sparkle of light between these areas, making the diamond come alive.

Facet Arrangement

The arrangement and symmetry of facets matter as they determine how light interacts with the diamond. A diamond with a well-arranged facet pattern enhances the brilliance, fire, and scintillation.


Though diamonds are hard, a good cut also ensures they are resistant to chipping or breaking. Durability is an essential factor, especially when the diamond is adorning your engagement ring. A well-cut diamond will not have any visible structural weaknesses that could jeopardise the longevity of your diamond’s beauty. 

Find Your Bespoke Diamond for Your Engagement Ring with Marlow’s Diamonds

Marlow’s Diamonds promises engagement rings with perfectly cut diamonds. Every diamond, whether mined or lab-grown, is carefully selected for its high-quality brilliance and beauty. This ensures that our diamond engagement rings are ready to symbolise your eternal love. 

Explore our collection of brilliantly cut diamonds for your engagement ring.

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