Engagement Rings with Sparkling Diamonds, Polished by Master Craftsmen

The story of the diamond’s enchanting brilliance starts with the skills of gemstone polishing artisans



 Known as the "king of gems," diamonds symbolize enduring radiance, making them a perfect emblem for wedding and engagement rings.


The raw, uncut diamonds, a gift of nature, are formed deep within the earth over billions of years, eventually brought near the surface by volcanic activity, and mined from diamond mines.



These rough diamonds don’t start out sparkling. They undergo a transformation through skilled cutting and polishing before they become the brilliant gems we all recognize.



So, how is this mesmerizing brilliance achieved?


Let’s explore the lesser-known process of diamond polishing.



Capturing the Essence of the Raw Stone in the "Stone Removal" Process



The first crucial step in diamond processing is "stone removal."


Each rough diamond is unique.


The challenge is to meticulously determine how to cut the stone to maximize its weight and brilliance while minimizing any inclusions.




Witnessing the Stone Removal Process



We had the opportunity to learn about this rarely seen process from Mr. Sekine of Eiwa Material.


Initially, the raw diamond is traced using specialized machines. Before these machines were developed, this process was done manually – a labor-intensive task that has since become much more efficient and accurate.



The machine scans the raw diamond and displays its three-dimensional information as a traced image.



Then, the machine suggests how to best position the diamond for cutting.



This data acts as a diagnostic report, guiding the optimal way to cut the diamond, considering inclusions and the internal structure of the stone.



Each raw diamond varies in shape and internal structure, affecting the number and size of stones that can be obtained. In the displayed case, the machine proposed cutting out two differently sized diamond roughs.


Following each diagnostic result, skilled craftsmen cut and polish the diamonds, creating the ideal finished stones.




Understanding the Best Stone Removal Process



Optimal stone removal means maximizing the use of the raw diamond. This requires the high skill level of experienced polishers.



For example, if a 2.0-carat diamond can be obtained, the priority is to maintain its size. For smaller stones under 0.5 carats, the focus shifts to brilliance and color, making it vital to consider inclusions.


Such discernment, highlighting each stone's unique charm, is the mark of a skilled polisher.



With expert hands, the following types of diamond roughs are produced:




Polishing without loss, retaining weight


→ large carat diamonds are produced

→ additionally, loose diamonds (small diamonds under 0.1 carats) are obtained




Avoiding inclusions and scratches for effective light entry and reflection



→ enhancing clarity and brilliance




Understanding Inclusions (Internal Imperfections)



Natural diamonds, formed deep within the earth, develop inclusions – mixtures of other mineral crystals or irregular atomic structures during their growth. These inclusions and surface blemishes can obstruct the diamond's brilliance.


The cutting of a diamond is precisely calculated to allow efficient light entry and reflection, minimizing the impact of inclusions while retaining as much of the raw stone as possible, resulting in larger, more brilliant stones.




Seeking Greater Brilliance



In Japan, the preference is for smaller diamonds with greater brilliance, making the quality of the cut crucial.



Among various diamond shapes, the Round Brilliant Cut is renowned for its exceptional sparkle.




The Round Brilliant Cut



When people think of diamonds, the Round Brilliant Cut often comes to mind.


Developed in the 20th century, this cutting technique involves creating 58 tiny facets, enhancing the diamond’s ability to reflect light.



The facets, including their shape, size, symmetry, and angles, are all precisely calculated to maximize brilliance. This delicate process is performed by hand.



Artisans with control and precision can produce Triple Excellent (3EX) diamonds, while only a select few can achieve the Five Excellent (5EX) standard.




Only experienced polishers can discern the subtle differences in hardness and characteristics of each diamond, using tactile feedback and sound during the polishing process. These delicately polished diamonds exhibit high symmetry.






One feature illustrating symmetry is the “Hearts & Cupids” pattern. In the video, the 5EX diamond on the left displays eight evenly shaped and spaced white arrows.


Compared to the EX cut diamond on the right, the difference in both shape and brilliance is evident. Diamonds displaying both arrows on the crown and hearts on the pavilion side are known as Hearts & Cupids diamonds, indicating high symmetry.




The Skill of the Artisan in Enhancing Diamond Brilliance



Having discussed the diamond cutting process, let's delve into the actual work involved, demonstrated by Mr. Sekine, an expert diamond cutter, with support from ith's representative, Ayu Takahashi.




The Diamond Polishing Experience




The tools used for polishing are surprisingly simple, resembling a record player. The diamond is set at the tip of the "needle," while the polishing disc acts as the "record," rotating to smoothly grind the diamond.



Though the process appears simple, correctly setting the diamond to align with the desired cutting direction is crucial. The mechanism is straightforward, but the process demands high-level artisan skills.


Smoothly polishing the diamond into a 58-facet structure requires careful attention and setting the stone at optimal angles.



The actual polishing process involves the diamond gradually being cut down, with vibrations transmitted to the fingertips.


However, determining how much has been cut and whether it's smooth is not easy, based solely on sound and touch.



Professional craftsmen repeatedly adjust the stone while polishing, gradually enhancing the diamond's brilliance.



When a skilled craftsman like Mr. Sekine works on the diamond, the interaction between the diamond and the polishing disc polishes both, resulting in a smoother disc post-polishing.


However, when a novice polishes, additional deep grooves in the direction of the disc's rotation can be seen, in addition to the intended radial lines.



Crafting the tools is another sign of an excellent artisan. Beyond just polishing discs, craftsmen often create and maintain their tools.



Key Points Supporting Superior Cutting Techniques



Assessing the raw stone
Determining the direction of polishing
Understanding the crystal structure (identifying cuttable and harder parts)
Creating and maintaining tools/discs
The skill level of the polisher





The Brilliance that Illuminates Life



Understanding how diamonds are processed can make these gems feel more accessible, even if you feel unsure about discerning their differences.




The high grades and prices of diamonds, such as 4C ratings or 5EX diamonds, reflect the careful work of artisans. As you learn more about the evaluation criteria, choosing a stone that feels more beautiful and valuable to you becomes easier.


Like meeting people, each gemstone possesses unique allure. At ith, our primary focus is ensuring that the chosen diamond is truly desired by the wearer. We offer a wide range of high-quality diamonds, each with distinct characteristics.


When you visit our atelier, enjoy the experience of finding the diamond that feels destined for you. Our concierges eagerly await your arrival.


Learn more about Diamond Features

View ith's Engagement Ring Collection

List of ith Ateliers



Engagement Rings with Sparkling Diamonds, Polished by Master Craftsmen