Diamond Expert

The name diamond is derived from the ancient Greek  Adámas, meaning "proper", "unalterable", "unbreakable “or "untamed".

Diamonds have been known to exist for at least 3000 years from what we know from ancient Indian history, however they only became well known and popular in the 19th century with the advent of increased supply during the Industrial Revolution.

Two key characteristics of a diamond are its ‘Hardness’ and high ‘Dispersion of Light’ making the gemstone useful for industrial application in relation to its hardness and adornment in jewellery through its ‘High Refractive Index’, or what is known as ‘Fire’ in the diamond.

Diamonds are most popularly known to be used as the gemstone in engagement rings, and this custom of using a diamond in an engagement ring dates back to the 15th Century.

With increased popularity in the 19th and 20th centuries, diamonds have become a highly traded commodity with many factors such as grading, cutting and source determining the value.

Diamond Source

Diamonds are mined throughout the world but the main countries where diamonds are found are Central and Southern Africa, Canada, Russia, India and Australia. 

Diamonds were originally found in alluvial deposits in Southern India, making it the leader in diamond production up until the 18th century. Now, diamonds are found in Kimberlite and Lamporite volcanic pipes.

A Kimberlite or Lamproite volcanic pipe is a subterranean geological structure formed by deep volcanic eruptions. These eruptions create a long carrot-shaped pipe, usually consisting of Kimberlite or Lamporite rock, and within this rock diamonds are found. 

There is a group of 4 key mining companies that control rough diamond production throughout the world: Dominion Group, Rio Tinto, Alrosa and Debeers. The Australian mining company BHP Billiton was also a major player in diamond mining with its ‘Ekati’ Canadian diamond mine, which it developed in the mid 1990’s.

BUNDA was approached by BHP Billiton at this time to exclusively market and sell BHP’s ‘Ekati’ diamonds to the Australian market under ‘License Agreement’ with the added benefit of the diamonds then unique ‘Known Source’ hallmarking system. 

This program of ‘Known Source’ marketing of diamonds has now also been developed and progressed by some of the other diamond mining companies in various forms, enabling BUNDA to supply many diamonds with the knowledge of their original origin. 

Some of the key mining companies, such as DeBeers still do primarily continue to consolidate their rough diamonds from all their various mines before sorting and selecting for cutting, therefore not enabling the ‘Origin’ of the stone to be known. 

BHP Billiton completed the sale of ‘Ekati’ to Dominion in 2013 however all the ‘supply chain’ processes established by BHP Billiton have been maintained and, as said above, developed further by the other major miners. BUNDA now refers to its diamonds with known source as ‘Eligible Mine of Origin’ (EMO) when selecting for its customers. 

Historically, BUNDA has been at the forefront of ‘Known Source’ gemstone supply and marketing. Prior to the BHP Billiton ‘Ekati’ deal, BUNDA did something very similar with Robert Wan, the world’s largest Tahitian Pearl farmer, with the introduction of ‘Tahiti Perles’ to the Australian market in 1998. This introduction to the Australian market of an exceptional selection of the world’s best Tahitian Black pearls direct from the farmer revolutionised the Tahitian Pearl business in Australia at that time, and was one of the primary forces in shaping the Australian South Sea Pearl business into what it is today. 

In all precious gemstone markets the ability to deal directly at the source, with the major miners or producers, enables the best value and quality to be passed onto the customer, and BUNDA continues to replicate this model of vertical integration, establishing key relationships with the world’s best sources of gemstones.

Diamond Cutting

Diamond cutting or faceting is the process of taking a ‘Rough Diamond’ crystal and ‘Polishing’ it down to a faceted gemstone. Because diamonds are one of the hardest materials on earth, other diamond coated wheels are used to grind/polish a diamond to the desired shape. 

The first step in the process of cutting a rough diamond crystal is to assess the crystal and what diamond/s can be cut from it. The assessment of each rough diamond takes into account what value in polished diamonds can be achieved from each rough crystal. It is important to note that not all cutters are looking to achieve a higher value in each polished diamond. To achieve a high value in a polished diamond, sacrifices in carat weight ‘yield’ must be taken. Some diamond cutters choose to cut lower value/higher weight ‘yield’ diamonds. At BUNDA we have always chosen to sacrifice carat weight ‘yield’ in order to have a beautifully cut stone and this starts right at the beginning of the planning process when assessing the rough crystals. 

After the planning process a diamond is ‘Cleaved’. Cleaving is where a rough diamond is sawed into pieces to then be further polished. ‘Polishing’ is the process by which facets are polished onto the diamond. ‘Bruting’ is a process where two diamonds are rotated against one another in order to create a round shape. In the past decade round brilliant cut diamonds have mainly had this bruted edge, then further polished or faceted to improve the finish in the diamond.

History of Diamond Cuts

Diamond cutting can be traced back to the 14th century when the point cut was first developed by the first known guild of diamond cutters based in Nuremberg in the Bavarian region of Germany. The point cut is simply polishing the existing octahedral shape of the natural diamond crystal, revealing the diamond crystal's natural adamantine lustre. Adamantine lustre is a rare occurrence in translucent minerals that have a very high lustre. Adaptations to the point cut were then made, firstly with the cutting of the top point off the point cut to create the ‘Table’ cut. The importance of the culet then became better understood, and cutters continued to modify the point cut by cutting the corners off the table cut creating the ‘old single cut’. What we know today in terms of the ‘fire’ or ‘high refractive index’ of diamonds was not yet known by the first diamond cutters but in the 15th century the concept of absolute symmetry was invented by a Flemish diamond cutter named Louis van Berquem. This theory was then progressed by other diamond cutters in the diamond cutting centres of northern Europe into the development of the Mazarin cut or what could be described as the original brilliant cut by the 17th century.

It is important to note that during this period Indian diamond cutters had also developed their own particular style of cutting, essentially known today as the ‘Rose’ cut. Due to the then divine status of diamonds in India the preservation of carat weight was of utmost importance and many of the original large and famous diamonds featured the rose cut style of a series of triangular facets in a symmetrical pattern on the top half with a flat base. A good example of this style of cutting is shown in the image below of what is now known as the Orlov diamond and is described as having the shape of half a chicken’s egg.

The concept of symmetrical cutting pioneered in the 17th century in Europe is what has lead to the classical understanding of diamond cutting as we know it today. By the 19th Century the Old European Cut was developed, the forerunner to the modern brilliant cuts we know today.

At the beginning of the 20th century new technology and machinery was being developed in the diamond cutting industry such as saws and lathes, enabling a more precise and complicated level of cutting to be applied to diamonds. With these developments emerged the ‘round brilliant cut’ and in 1919 a polish diamond cutter by the name of Marcel Tolkowsky (engineer by education) analysed the round brilliant cut making assumptions about the brilliance (White light) and fire in a diamond and balance between the two. Tolkowsky’s work and calculations, revolutionary in their day, have served as the benchmark for all future modifications to the modern round brilliant cut. Widely acknowledged as the father of the Modern Round Brilliant, Tolkowsky’s work was the tipping point into a new understanding of the fire and life uniquely held by diamond crystals, and how diamond cutting design and proportion can accentuate this incredible beauty.

Diamond Cuts (Shape)

As we have learnt from the previous chapter on Diamond Cutting, the cut (shape) that the diamond cutter chooses to create is generally determined by the shape and size of the rough crystal and the size and location of the inclusion in the rough crystal. 

Diamonds crystals are part of the cubic crystal system and generally occur in two shapes. Most commonly rough crystals form in the shape of Octahedra (two pyramids joined at the base) and these are generally then cut into round brilliant cuts as there is a good opportunity to cut two stones from the one crystal due to its shape. The other shape diamond crystals form in is a Macle (this shape occurs when the diamond crystal has malformed or ‘twinned’ creating a lozenge or longer flatter crystal. These Macle crystals are often used to cut fancy shape diamonds.

Therefore, we have two specific categories within diamond cut shapes. Round Brilliant Cuts and Fancy Cuts. Round Brilliant cut diamonds are the most commonly cut diamond shape and as a rough estimate would consist of 50% of the total polished diamond market. Fancy shape diamond cuts make up the remaining 50%. Round Brilliant cut diamonds, by nature of their round shape being cut out of a square crystal, are generally priced about 20% more than the equivalent fancy cut diamond due to their lower yield in carat weight from the original rough.  

Round Brilliant cut diamonds are also popular as they enhance the natural ‘fire’ diamonds have through the crystals ‘high refractive index’. We know that proportion and symmetry in diamond cutting enhances the fire in a diamond and the round brilliant cut does this extremely well due to its round shape. There is a lot of information in the market provided by various sources such as gemmological laboratories and diamond brands about the level of fire and brilliance coming from various variations in proportions of round brilliant cuts. At BUNDA we look at a wide range of data through our DNA reports prior to a diamond going off for certification at a laboratory in order to assess the cut quality and in turn beauty of a diamond.  We will cover this area in more detail in future chapters. 

Fancy cut diamonds are all the diamond cut shapes other than round brilliant cuts. Generally, fancy cut diamonds are cut from the malformed roughs (Macles) that occur when the diamond crystal ‘twins’ and does not form in the classic Octahedral shape. 

You will know the names of most of the classic fancy cut diamonds: Emerald, Cushion, Princess, Oval, Square Emerald, Marquise etc. All fancy cut diamonds are categorised into 4 groups.  The first group is ‘Modified Brilliant’. As the name suggests these cuts are all derived from the classic round brilliant cut but they are modified. A good example of one of these cuts is the Princess Cut. It is a cut that has a square shape from the top but the crown and pavilion have brilliant style faceting. 

The second group within fancy cut diamonds is ‘Step Cuts’. Steps cuts are fancy shape diamonds where the facets do not cross each other in a diagonal fashion in the pavilion or crown. Again the name of the group of cuts is a good description for the category, when you look at a step cut the facets look like steps. Step Cuts date back prior to the brilliant cut and are admired by diamond connoisseurs all around the world. If we look at the original ‘Table Cut’ or ‘Single Cut’ these are essentially step cuts and it is this history of diamond cutting style that makes step cuts a key category within the polished diamond market. The most common step cuts are the Emerald Cut or Square Emerald Cut (Asscher Cut).

Thirdly we have Mixed Cuts. As the name suggests this is where the cutter has mixed the brilliant and step cutting styles together in one cut. These hybrid cuts are rarely seen at BUNDA as they are usually cut to simply yield more weight from a particular rough crystal or to hide a significant inclusion by adding brilliant cut facets to a particular face of a diamond. 

And the final group within fancy cuts is the ‘Rose’ cuts. As we have learnt previously Rose cuts were developed by Indian diamond cutters where they applied a series of triangular facets in a symmetrical pattern on the top half of the diamond crystal with a flat base. Ancient Indian Mogul diamonds were cut in the rose cut style and sometimes rose cuts can be described as ‘Mogul’ cuts.

Gemmology, Labs & the 4C’s

Gemmology is the science relating to natural and artificial gemstones. It is related to mineralogy and many professionals who work within the jewellery industry academically train in order to gain qualification to identify gems. 

Basic education in the field of gemmology began in Great Britain in the 19th Century. The first known gemmological qualifications came in 1908 from a gemmological committee set up within the National Association of Goldsmiths of Great Britain (NAG). This subcommittee then matured into the Gemmological Association of Great Britain (GEM-A) with the aim of offering the jewellery trade the best possible education and qualifications around gemmology. 

At the beginning of the 20th century the creation of synthetic gemstones such as rubies and emerald and the progress being made in cultured pearls meant it was essential there was formal education available to the industry. In 1929 the first American graduate of the GEM-A Diploma in the Gemmology was Robert Shipley, who then went on to establish the Gemmological Association of America (GIA) and the American Gem Society (AGS). Shipley’s initial work at the GIA is the foundation of what gemmology is today and in 1953 his diamond grading system (The 4C’s) was adopted as the international standard by which all diamonds are graded. 

BUNDA has always had a strong connection with Gemmology, starting with Veronica BUNDA pioneering the use of gemmological certification for all estate and antique jewellery BUNDA was dealing in the 1980’s. This was not a common practice at this time with most antique and estate jewellery being traded simply without any guarantees. 

Over time, BUNDA has employed and trained many staff as gemmologists and Ben Bunda is a graduate gemologist. This strong connection and learning within gemmology enables BUNDA to always be at the forefront in the field of diamonds and gemstones, offering our customers an exceptional level of knowledge and warranty on all pieces we create.

The 4 C's

BUNDA Diamond DNA Data 

In the previous chapter we have reviewed how the classic understanding of diamonds has been formed over the duration of the 20th Century. The pioneer gemmologist Robert Shipley lead the GIA to the forefront of Gemmological standards and established the 4C’s as the foundation for the diamond industry and consumers to have a simple system to grade and evaluate diamonds. 

Although an excellent grading system, there are many more factors that affect the value and beauty of a diamond and the generic diamond certificate does not have enough information to truly inform us or the buyer about the stone. Over the past 20-30 years there has been a significant amount of work done by various gemmological labs in trying to understand how the cut of a diamond affects the performance of light (Brilliance/Fire) in a stone and BUNDA has always been at the forefront of these learnings. 

Over the past 25 years, Ben Bunda has read extensively and also widely travelled participating in diamond industry learning events to gain a comprehensive understanding of diamond cuts. This, combined with actual trading experience like no other, forms the essence of a BUNDA Diamond. Like any profession, it takes years of dedication and experience to attain industry wide recognition as an expert in the field.

At BUNDA we seek to combine this knowledge and experience along with advanced technology into a clear and succinct framework for our customers so they can have the opportunity to truly understand what makes a diamond a great stone over another. At BUNDA we call this our Diamond DNA Data. 

BUNDA Diamond DNA Data is what we know about a polished diamond before it goes to the laboratory for grading. As noted before, classic diamond certificates are set on the foundation of the 4C’s and do not provide all the information required to obtain a full understanding of how well or bad a diamond has been cut. Therefore at BUNDA we use diamond DNA data to select our diamonds and we also share this data with our customers in order to help guide them in the selection of the very best possible diamond for their needs.

Diamond Treatments (Enhancement)

Diamonds can be treated like any other gemstone in order to improve or enhance its gemmological characteristics. Unlike other gemstones, no treatments/enhancements are deemed to be acceptable within the category of diamonds. 

Unlike in coloured stones, it is essential for any treatment/enhancement applied to a diamond to be disclosed at the time of sale. Government agencies such as the US Federal Trade Commission, in partnership with industry bodies like CIBJO (The World Jewellery Confederation) enforce this process. 

Diamond enhancements/treatments are highly controversial due to the fact that essentially they alter/improve the clarity or colour of a diamond. With a standardised global grading system being in place for nearly 80 years underpinning the industry and global trade of diamonds it is essential the industry is always completely transparent regarding enhancements or treatments in order to protect consumer confidence in diamonds.

Clarity Enhancements

The clarity, or purity, of a diamond refers to internal inclusions of the diamond, and is a key factor in determining a diamonds' value. Common inclusions that appear inside diamonds are black carbon spots and small cracks, commonly referred to as fractures or "feathers".

Laser Drilling

The development of laser drilling techniques has increased the ability to selectively target, remove and significantly reduce the visibility of black carbon inclusions on a microscopic scale. The laser drilling process involves the use of an infrared laser  to bore very fine holes into a diamond to create a route of access to a black carbon crystal inclusion. Once the location of the included black carbon crystal has been reached by the drill channel, the diamond is soaked in sulphuric acid to dissolve the black carbon crystal. After soaking in sulphuric acid the black carbon crystal will dissolve and becomes transparent (colourless).

Fracture Filling

Fracture filling as a method to enhance gems has been a known process in gems over 2,500 years old, however a diamond's high refractive index requires a more advanced solution than simple wax and oil treatments. Fracture filling became available roughly 20 years after the time the laser drilling technique was developed. Fracture filling makes tiny natural fractures inside diamonds less visible to the naked eye or even under magnification.

Following laser drilling and acid-etching of inclusions and/or if the fractures are surface-reaching; a specially-formulated solution with the same refractive index approximately to that of a diamond is applied with some pressure to fill the fracture and make the inclusion(s) in the diamond more difficult to see. 

Colour Enhancements

There are three major methods to artificially alter the colour of a diamond: 

• Irradiation
• Coatings
• HPHT (High Pressure Heat Treatment)

The first two methods can only modify colour, usually to turn an off-colour ‘Cape’ (Light Yellow) series stone into a more desirable fancy-coloured stone. Conversely, HPHT treatment is used to modify and remove colour from either rough or cut diamonds, however not all diamonds are treatable in this manner.  

Irradiation

The irradiation method (exposing the diamond to radiation) essentially produces a thin "skin" of colour, therefore it is applied to diamonds that are already cut and polished. This irradiation method makes diamonds become a more distinct fancy colour (not white) and then generally a further application of annealing is applied to turn the colour into more distinct shades of orange, pink or yellow. 

Coating

Coating a diamond is where a thin layer of laboratory grown diamond and or plastic is applied to a diamond in order to improve the appearance (brilliance) or colour of the diamond. 

HPHT (High Pressure Heat Treatment)

HPHT is the process of applying High Pressure and High Heat to alter the colour of a diamond. This process can make diamonds more white and/or more fancy in colour; Pink, Yellow or Blue.

Diamond Treatment Summary 

At BUNDA we do not sell or trade in any treated diamonds. In the case where we may buy a diamond without any gemological report (estate and or antique diamond) we will subsequently have the stone tested geologically to confirm there has been no treatment or enhancement of the stone.   

References

• Gem-A, The Gemolgical Association of Great Britain  https://gem-a.com/
• GIA, The Gemological Association of America https://4cs.gia.edu/en-us/