Modern Mogul Cut Diamond – a Fast Forward (R)evolution

May 3, 2021

Introduction – Revolutionizing of the Mogul Cut Diamond~

For those who have been following my recent Lab Grown Diamond (LGD) journey “Mughal (Mogul) Cut Diamonds – Reviving the Mountain of Light!” which tells my experience on the interpretation of the historic Mughal Cut diamond design, this next journey of mine is a natural evolution of my current affairs. Shouldn’t come to anyone who knows me as a surprise.

I do warmly suggest to first read my previous blog article which will mend naturally into this continuation article.

Initially, when I selected the few LGD’s from Lusix, I didn’t have any set plans for them but figured I have quite a few ideas which I would like to materialize with LGD’s. Little did I know that my journey bringing the historic Mughal Cut back to life will spark up a new gem concept (no pun intended).

After realizing its optical capabilities, my next natural reaction would be to attempt and refine the Mughal faceting technique into a 21st. Century potential design. Meaning utilizing my optical knowledge and lapidary skill to further research and explore and see where this takes me…

Since a definite play-of-light was determined on my “new” historic version, discovering its light potential translated into an appetite for more… For this to materialize, three dimensional optical precision was to become the basis for this next journey of mine.

This article offers excerpts of my recent journey.>

First Dilema – Shape & Form

Since facet design was not questionable as I am adopting the actual historic Mughal faceting design, my primary dilemma was to which shape and/or form to design.

In my nature, my first reaction would be to explore a unique shape, most of my professional life, I have been swaying away from the popular round brilliant cut diamonds.., naturally my first instinct was a curved, albeit non-rounded form.

After more thoughts on the subject, I came to the conclusion that starting with a non symmetrical faceting/fold design would complicate the way forward on such a multifold facet design. I chose the safer, more efficient route and simplified what will turn out as a very complicated journey. For the first time, I was about to design a round shaped diamond…, albeit based on a 400-500 years old design.

The Cutting Journey Begins – Preliminary Shaping the Rough

As mentioned in our previous two articles on LGD’s, currently most LGD rough are grown to service the most commoditized diamond shape, the round brilliant. This fact actually came to my favor as all I needed to pass our first obstacles was eliminating the various surface irregularities caused during the growth process (mostly bordering the main rough diamond).

As can be noticed in fig 1, we started grinding away and cutting out some irregularities which will naturally get us closer to a rounded outline. Video 1 displays it more clearly.

Contrary to the more common practice of preparing and planning rough diamonds by virtual 3D design and allocation of the polished model inside the rough volume, this new journey did not allow such advanced luxury and we had to hand-cut this first prototype from start to finish subsequently designing my way forward.

Dark irregularities – the border between diamond & polycrystalline materials

Fig 1 – Dark irregularities – the border between diamond & polycrystalline materials

Video 1 – Dark irregularities contouring the whole lab diamond

Locating the Lights Within

Cutting the first historic version just a couple of months ago gave me the advantage of learning the relative facet slopes required to move into this new journey. After grinding approx. twenty five percent of the weight-mass just centering the model I already located the light effects I am looking for (see videos 2 – 3).

Video 2 – Identifying total internal reflections (TIR) 

Video 3 – ASET translation of video 2 – red: direct light return

Next came the subdividing of the contour by hand cutting until we got to the designed fold denomination depicting a rounded shape, in our case a sixteen fold design. This stage is so crucial it will become the base that determines the achievable 3D optical precision level. It is a long painstaking process that requires plenty of experience to achieve manually. (see fig 2)

Precise divisions, from a 8 to 16 fold symmetry

Fig 2 – Precise divisions, from a 8 to 16 fold symmetry

As we were moving forward with the contour shaping I kept following and learning the physical cutting effects of the light paths within the diamond. It was really interesting to learn that every additional facet affected its light behavior. (see fig 3)

Light return dynamics in motion (change of color = different light capturing directions)

Fig 3 – Light return dynamics in motion (change of color = different light capturing directions)

Precision Faceting the Modern Mountain of Light

Once the outline was precisely completed we could move on to the next stage, the placing of the first layer of facets covering the whole dome which required another long and strenuous process. I must admit it was a more efficient process than we encountered on the shapeless historic version because we were working on a symmetrized form with three dimensional logic.

With its completion, the faceted dome would entail three rows of 16 trapezoidal facets each, 16 long rectangular girdle facets at the base of the dome and 16 additional tiny trapezoidal facets on the underside of the base. A total of 80 facets (not including two additional base & table facets).

Executing such a precision craft is just so far away from any mainstream cutter today that only specialized hands with great three dimensional knowledge and experience can tackle such a task. The mind needs to work constantly while the hands keep steady and more importantly calm.

It’s a long orbiting process, you start with one facet by cutting it to an exact angle and azimuth (index) measurement, then final-polishing and move on to the next facet repeatedly…, at the same time staying within precise facet junction symmetry, an art executed by eyesight only .

This is by far a more complicated task than cutting high precision standard brilliant or step-cut designs. (see fig 4)

To elaborate more – what physically happens is…, once you orbit the diamond with precisely placed facets, all the inevitable miniscule errors endured along the way accumulate at the ending/starting point and this is something we try to avoid. This is only possible when executed by the mind, hands and eyes of an experienced lapidary with great three dimensional understanding.

Unique & precise orbital facet placements

Fig 4 – Unique & precise orbital facet placements 

Discovering a 360 Degree Play of Lights

Again, throughout the process, I kept following the lights, both virtually and realistically. The big difference this time as compared to the previous historic version, I was studying this LGD on all its directions focusing mainly on the top view (e.g. small mogul polished table on top of the dome) and bottom view, through its large polished base. (see fig 5 and fig 6 )

Studying light behavior in ASET environments – top of dome

Fig 5 – Studying light behavior in ASET environments – top of dome

ASET light reflections as viewed from its base – tilting

Fig 6 – ASET light reflections as viewed from its base – tilting

As hinted by me during my previous article, the Mogul Cut design holds a 400-500 year secret within itself. It has the capability to demonstrate wonderful play of lights from both its polar sides, albeit different optical objectives & tastes.

The following is a simplistic laymen term explanation on both.

From its domed side, light enters the diamond from the top reflecting upon its singular and large base facet returning back to the viewer while splitting itself upon exiting the multifold faceted dome. (*see fig 7)>

Light ray entering from the domed side reflecting upon the internal base facet

Fig 7 – Light ray entering from the domed side reflecting upon the internal base facet

From its base side, light enters directly through the singular base facet (as opposed to being split by crown facets on regular cuts) and reflects back from the multifold inner facet world of the Mogul Cut dome (*see fig 8). The play of light revealed is just astounding!!

*raytracing tested in fig’s 7 & 8 are on the completed modern Mogul Cut.

Light ray entering through the base facet reflecting upon the internal faceting of the dome

Fig 8 – Light ray entering through the base facet reflecting upon the internal faceting of the dome

For realistic photographs depicting this stage, I have only a few cell phone videos and pictures I captured on the spot so please excuse the quality of these pics and videos. They were taken and collected for my records which I share with you in this article.

Video 4 shows the LGD covered with its preliminary facets confirming total internal reflections (TIR) while fig 9 gives a top viewing snip confirming spectral effects.

Video 4 – Bright internal flash events confirming Total Internal Reflections 

Confirmed spectral effects (diagonal marks = unpolished base facet)

Fig 9 – Confirmed spectral effects (diagonal marks = unpolished base facet)

Brillianteering the Modern Mogul Cut

At this stage I had a three dimensional balanced faceted dome covered with precisely placed trapezoidal facets (except for the rectangular girdle facets).

It was time to replicate the historic Mogul Cut’s unique triangular facets that will ultimately cover the whole diamond form and allow the dancing of the lights within itself. An orchestra of lights lost hundreds of years ago and which I believe is not physically physically known presently. 

During the preliminary faceting I had a chance to test by polishing two adjacent triangular facets to better study and understand their optical effects. Fig 10 shows a sequence of viewing positions showing part of their optical effects (cell phone pictures).

Triangular facet – internal & external optical effects

Fig 10 – Triangular facet – internal & external optical effects

Obviously a similar effect will be noticed when viewed through its base side, although the picture is not clear as I would like but fig 11 demonstrates the triangular facets are reflecting white/bright light in the middle of a darker obstructed environment.

Triangular facet effects (red surround) as viewed through the diamond’s base facet

Fig 11 – Triangular facet effects (red surround) as viewed through the diamond’s base facet

This repeating orbital procedure again challenged our cutter because it was to be fully executed by *hand based on the precision levels of the preliminary base facets. It was to be a symmetrical chain of events repeated super-precisely thirty two consecutive times. Unfamiliar territory to your usual diamond cutter. (see video 5)

*unaided by any non-contact measuring scanners/tools

Video 5 – Three dimensional precision – Mogul style faceting

The historical Mogul Cuts usually possessed out of form bases (widest & heaviest part of the dome) lacking any girdles which required special lapidary considerations and design to allow a flowing with the unique overall symmetry of the already out-of-balanced dome.

Since I was engaged in reinterpreting a modern version, I needed to invent a girdle/base design to compliment the unique overall three dimensional symmetry of the diamond while conforming to the ancient Mogul style. In an attempt to keep it simple as possible, I thought a smaller mirrored replication of the historic kite-shape would fit beautifully. (see fig 12)

Innovating with traditional mogul style kite shaped facets

Fig 12 – Innovating with traditional mogul style kite shaped facets

Again, applying by polishing sixteen such small & precise kite shaped facets required both specially tooling aides (executed at very steep angles) and a repeatable calm cutter’s state of mind. We just couldn’t afford to not do it right! The smallest faceting error would require a long strenuous repairing process which was to be avoided as much as possible.

Last Minute Touches

Just like with any three dimensional precision cut design, it always entails some more “last minute touches” that never seem to end. I always say there is no such thing as a perfectly cut diamond (period).

In our case, since this is a completely new multifold-facet design (albeit a reinterpretation) it required more attention than your usual…, I needed to put a stop somewhere and it did come at a cost of near perfection!

The most crucial and final element for me was to finetune the very small and thin trapezoidal facets we incorporated on the outer edges of the base of the dome. (see fig 13) This was done mainly to keep in line with present safety protocols such as setting & faceting limitations.

A row of thin facets contouring the outer edges of the large faceted base

Fig 13 – A row of thin facets contouring the outer edges of the large faceted base

As mentioned above, this is all new to me, this first specimen is my learning notepad. Just when we were certain we locked the facet angles in an exact configuration, our last minute touches reminded us how sensitive light is and it moved us a bit off-course…, nothing major but still a true curiosity. It’s a bit too technical so I choose not to get into it in this article.

The new modern interpretation of the historic Mogul Cut design was ready to be introduced! Technically it’s a symmetrical feat, fig 14 shows parts of the dome top faceting angle measurements…, these measurements are based on a three dimensional scan so error limitations are present. But anyone familiar with such measurement maps will understand the effort behind the creation of this new modern interpretation of the historic Mogul Cut diamonds.

Partial dome view of the facets and their corresponding angle precision

Fig 14 – Partial dome view of the facets and their corresponding angle precision

Introducing the Mogul Cut – 2021

After twenty days, the first modern Mogul Cut diamond was ready to display its unique optical play of lights. The problem…,the more I experimented with photographing this modern version or its historical version the more I got to reveal the deeply rooted optical secrets this long lost cut was hiding deep within itself.

After forcing myself to stop photographing these two mysterious diamond designs (BTW, all photography done by me personally) I turned to a professional videographer to try to film some videos to relay what I have learned and noticed.

Ironically the videographer and myself found ourselves transfixed to the display screens which delightfully prolonged our sessions. The light show illuminated from these two LGD’s were outstanding and from another world…, long lost and still presently unknown in our little industry as of yet.

High Quality Video and Gallery

Video 6 – Modern Mogul Cut Diamond Completed

About Yoram Finkelstein

About Yoram Finkelstein

Mr. Finkelstein a proud second generation Diamond cutter. In 2010 He founded GemConcepts Ltd. which specializes in designing and cutting unique Diamonds using a new approach, a new philosophy. GemConcepts design Diamonds that mix the “old world” approach with the newest cutting-edge technologies.

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