Diamond Facets – The windows to light

Aug 1, 2019

The beginnings: Diamond facets – a window into a diamond

The first optical diamond facets ever applied onto a diamond was when table cut (fig. 1) diamonds started appearing in Europe around the 14th Century.

The large table facet which characterized the table cuts allowed for the first time in history an internal look into a diamond reflecting the octahedron or Point Cut (fig. 1) four fold symmetry.

Around the same period mainly in India, randomly applied faceting was more utilized to shape out irregular rough diamond forms and to cut and polish out unwanted internal inclusions.

There wasn’t really any optical objective except perhaps some shimmering obtained by the accidental and disorganized application of facets and movement.

Cutting a table facet which acted as a large window into the diamond revealed the optical splendor diamonds offered when met with light, and when in motion revealed the play-of-light phenomena which still today causes humans to lose a heartbeat with certain excitement.

Figure 1 First diamond cuts

Second step of cutting – the first diamond facets planning – rose cuts

Before cutting and polishing was discovered, cleaving was the only way to cut or divide a diamond, this also allowed an internal view of the diamond when observing through the cleavage planes but the optical effects were not noticeable as with the table cuts.

The art of cleaving produced flatish formed diamond cleavages as a bi-product. In time, these cleavages developed into flat-domed Rose Cuts. Naturally the first faceted Rose Cuts didn’t possess neatly placed facet arrangements and wildly covered the dome of the cut offering some mild light shimmerings.

The main larger diamond after the cleaving would be cut en-Indian, usually to forms and shapes which populated the period like Mughal and Tavees cuts, such were actually the preceding cuts to the Old Mine and Briolettes cuts, and with progression received their more arranged and beautiful faceting styles.

Rose cut diamond

Mughal cut diamond

The next step – faceting reaches Europe bringing cuts to the next level – old mines

When Diamonds began reaching Europe around the 14 & 15th centuries, a few cutters started gaining reputation for themselves thanks to their unique skills, capabilities and knowledge in the new mineral.

As time evolved, a few cutters were already building a name for themselves and were being credited in some literature’s of the era. One such example, Ludwig van Berquem who supposedly studied diamond cutting in France in the 15th century and was considered as someone who mastered the art for that period.

Around the 17th. century, a Venetian diamond cutter named Vincenzo Peruzzi was credited with the development of the first 58 facet brilliant faceting design which preceded the standard brilliant.

At that period, this cut was called the triple cut and followed the natural octahedron outlines resulting of the square and rectangular shaped brilliants better known today as Peruzzi Diamonds.

The popularity of the Peruzzi Diamonds which lasted for quite a few centuries, was eventually improved into the rounder shaped Old Mine Cuts and when mechanicalized brutting was invented their production volumes were minimized and the standard modern round brilliant was born.

Step and brilliant facet designs – the normal

Natural rough diamonds come in all sorts of forms and textures, and polishing facets require the flattening of small proportional multiple surfaces, cutting larger facets means greater amount of weight loss which most cutters avoided and is still very true in the present day.

Two basic faceting designs have been practiced by diamond cutters over the centuries, the brilliant-style and step-style cuts, over time, some hybrid cuts have come and gone, but all and mostly cut on the foundations of either the brilliant and/or step cut designs.

Elongated octahedrons or other elongated raw shapes required a different faceting composition than the more rounded and squared shapes. The former would require multiple elongated facets which would cover substantial parts of the diamond surface form and length.

Table cuts were considered the first polished diamond cuts, after the cutting of the table facet, the next natural progression was to apply facets to the four natural crown & pavilion octahedron planes.

Faceting directly parallel to the natural diamond planes is practically impossible, an angle is required in order to cut through the material because its hardness and grain directions.

Polishing the four crown facets contouring the table cut’s table was accidentally the first experimentation leading to the step-cut design. On elongated rough shapes, cutters would further break up the single crown facet by adding additional elongated and trapezoidal shaped facets parallel to each other.

The step-cut was born, a faceting design supported on the foundations of horizontal facet divisions parallel to the girdle.

Step cut diamond

On shorter square and rounded rough forms cutters would apply shorter and smaller facets covering the sections of the rough diamond surface.

Such faceting required a different method and symmetry than the elongated shapes and were based on vertical facet divisions perpendicular to the girdle plane.

These faceting methods evolved with time into the brilliant cut and were made of a myriad of smaller lozenge, trapezoidal and triangular facet shapes and forms. The brilliant faceting style allowed a completely different appearance than what step cut designs offered.

Brilliant cut diamond

Modern Brilliant & Step cuts

At the end of the 19th century and more than 200 years after Vincenzo Peruzzi’s brilliant cut development, Henry Morse from Boston developed the first standard ideal round brilliant cuts.

A few decades later Marcel Tolkowsky wrote his thesis “Diamond Design, A Study of the Reflection and Refraction of Light in a Diamond, 1919”.

For the next century, cutters around the world would cut round brilliants based on their formulas with minute but significant differences offering numerous visual flavors.

It depended on where geographically the diamonds were cut, names such as the Amsterdam, Lisbon cuts etc… starting to pop up as differentiation’s.

At around the same time 1902, Joseph Asscher of Amsterdam took the step cut design further and developed the square Asscher Cut diamond, a formulaic square octagonal shaped step-cut design which was built on the foundations of the eightfold symmetry (four main and four corner breaks).

The Asscher cut took after the green emeralds that were produced to step cut designs mainly because of the Beryl mineral form (long octagonal cylinders). The main and major difference was that cutting diamonds into such cuts would require optical calculations for light behavior, the results granted the Asscher firm a justifiable patent.

The Asscher Cut was the first signature diamond cut to ever be patented, rumors tell the patent lasted to about WWII and today is considered a generic cut. (Not to be mistaken by the newly patented “Royal Asscher Cut”).

It wasn’t until another full century passed by that the round brilliant cut moved into its next modern era (still relevant today), this happened thanks to two gemological laboratories who after extensive research on cut disrupted the majority of the cutting industry worldwide by implementing a unique cut grade.

These two laboratories are AGSL (American Gem Society Laboratories) and GIA (gemological Institute of America) who developed cut grades parameters forcing cutters around the world to adapt and deliver a better more visually precise design body that took real light calculations and considerations into account.

AGSL later converted from a two dimensional cut grading system into a three dimensional system based on actual ray tracing technology for each facet individually. AGSL is the current leader in cut research & grading.

Diamond Facets roles – the relation between facets and light

This is a very complicated subject and I will try to touch on it in general layman terms.

Facet surfaces when applied to diamonds & gems in their raw forms actually allow a flat entry window for light waves to enter, travel and exit the diamonds & gems medium.

In diamond material, light enters the diamond through a facet (usually from above) while slowing down its speed and bending its rays, light continues its journey inside the diamond until it hits the bottom part or what is known as the pavilion facets. Light then bounces-reflects back white light or refracts into spectral colors radiating its play-of-light back to the viewer.

Cutters must take combined crown (upper) and pavilion (lower) angle combinations into account when cutting diamonds (they are interconnected).

Diamonds have a critical angle meaning that if the relation between the angles are not placed correctly, the light entering the diamond will leak out through its pavilion and fail to reflect back to the viewer. In such a case viewers will notice a see-through (worse-case) or bright mushy-like appearance better known today as “crushed ice”.

On the other hand, correct light reflected angles are very sensitive and require precision of facet placements. Light can reflect back if angles are chosen correctly, if not, the facets will reflect objects in the environmental space (like the viewer itself, furniture etc…).

Such reflections are called light obstructions and if overly localized will cause diamonds to appear dark and lifeless.

Some obstruction is important and allows the contrast necessary to exhibit the (on-off) play-of-lights diamonds are famous for when in motion. There is need for obstruction which must be balanced in order to let the diamond exhibit its optical splendors.

In plain terms, pavilion facets act as mirrors and will reflect back the environments they catch, this is why the relation between facet angles and light entry are critical in order to produce a well balanced cut and beautiful diamond.

Single ray journey through a diamond – Photo courtesy of DiamCalc

Multi rays journey through a diamond – Photo courtesy of DiamCalc

Diamond Facets Structures: Trapezoidal, Triangular and Lozenge

Depending on the length to width ratio of the rough, cutters would determine which faceting design would economically favor the particular shape being cut.

When step cut facet designs are considered, practically the majority of the diamond surface is polished with multiple long and narrow trapezoidal shaped facets reflecting slower, longer and narrower flash events.

As mentioned above, brilliant faceting designs were built on vertically fold facets (perpendicular to the girdle) which allowed easier subdivisions of the main facets and translated into multiple lozenges and triangular shaped facets.

Such smaller facets shapes and surfaces allowed the multiple splitting of the lights into smaller-faster flashing events which differed greatly from the step-cut display of lights.

trapezoidal diamond facets

Trapezoidal diamond facet

Triangular and lozenge diamond facets

Lozenge and Triangular diamond facets – Lozenge in red and Triangular in blue (total of 4)

Diamond Facets surface sizes – candle lights vs. modern lighting

As we know understand, diamond faceting is a few centuries old and began well before the invention of the electricity. Naturally diamonds cut pre-electricity periods were cut to compliment warmer-lower light derived from candle lighting.

After the electric invention, cutters needed to take stronger lighting environments into account forcing them to adapt their cutting styles and techniques to accommodate these new lighting environments.

Funnily, the base of the cut stayed structurally the same, in brilliant cuts that means the single cut (Fig. 1) or the eight crown, eight pavilion facets before the brillianteering stage. The main differentiations between brilliant cuts from pre & post electric time is the applied angle formulas and way the brillianteering was applied.

In the older versions, crown heights were significantly higher than in their modern peers, this translated into larger crown facet surfaces. Same with the pavilion facets, cutters applied very short triangular lower girdle facets to allow large pavilion main facet surfaces. Such were required to allow the catching and reflecting of the low lights which candle lights offered.

In the modern version the opposite applied. Stronger lights required smaller facet surfaces in order to split the lights into smaller but faster flashing events delivering the required brilliance, fire and scintillation such modern cuts display.

Crown heights were lowered significantly which created smaller crown facet surfaces while the triangular lower pavilion girdle facets were cut much longer and produced long and thin facet shapes dividing each of the eight pavilion mains into three elongated facets from girdle to almost reaching the culet.

More diamond facets = more life?

There is a long philosophical discussion amongst industry professionals about the preferred number of facets needed to deliver maximum brilliance, fire and scintillation. Some say the more the merrier, some the opposite.

I personally belong to the later group but there is no avoiding some designs which possess more than the standard 57/58 facets are actually beautiful diamonds.

My preferences come from experience and the optical knowledge I absorbed through the three decades I have been in this industry. As a scientific fact, I know that a spectral colored flashes must be large enough for our human vision to notice the colors.

This mere fact means that the more faceting you apply, the smaller their facet surfaces which scientifically wont allow us humans to notice colorful fire but we will be able to notice the bright brilliance translated into much smaller white flash events, a definite scintillating affair.

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Peruzzi Diamond displaying Large facet surface flashes


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Modern style Cushion Brilliant exhibiting Smaller facet surface flashes

GemConcepts approach to cutting in general and diamond facets in particular

I much prefer lower numbered – larger facet styles and surfaces which naturally produce larger & slower flash events allowing significantly larger refractions of spectral colors. Our human eyes will get to enjoy this optical phenomena to a greater extent. And in “my book” this phenomena is inseparable from the beauty of diamonds.

Twenty years ago I made a strategic decision that all my diamond works will possess significantly higher crowns returning to diamond design roots. Higher crown heights would produce significantly larger facet surfaces in conjunction with a smaller table.

Producing higher crown heights would allow not only larger facet surfaces but also distinct slope and azimuth deviations between the facets. This eventually changes the whole optical potential and the way diamonds appear and play their lights.

Basically, we at GemConcepts utilize both historic and modern planning and cutting techniques to bring beautiful diamond cuts which play the lights in a unique fashion, both old and new cut worlds created in this ultra modern era.

This allows us to offer a plurality of diamond cut options which were developed over the course of diamond cut history spanning well over four centuries.

The options are really unlimited !

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.

  1. Elizabeth

    Very informative. Thank you.

  2. Logan Haase

    This was an incredibly informative and easy to understand read! Thank you!


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