Diamond cutting is the practice of shaping a
diamond
Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the Chemical stability, chemically stable form of car ...
from a rough stone into a
facet
Facets () are flat faces on geometric shapes. The organization of naturally occurring facets was key to early developments in crystallography, since they reflect the underlying symmetry of the crystal structure. Gemstones commonly have facets cut ...
ed gem. Cutting diamonds requires specialized knowledge, tools, equipment, and techniques because of its extreme difficulty.
The first
guild
A guild ( ) is an association of artisans and merchants who oversee the practice of their craft/trade in a particular area. The earliest types of guild formed as organizations of tradesmen belonging to a professional association. They sometimes ...
of diamond cutters and polishers (Diamantaire) was formed in 1375 in
Nuremberg
Nuremberg ( ; german: link=no, Nürnberg ; in the local East Franconian dialect: ''Nämberch'' ) is the second-largest city of the German state of Bavaria after its capital Munich, and its 518,370 (2019) inhabitants make it the 14th-largest ...
,
Germany
Germany,, officially the Federal Republic of Germany, is a country in Central Europe. It is the second most populous country in Europe after Russia, and the most populous member state of the European Union. Germany is situated betwe ...
, and led to the development of various types of "cut". This has two meanings in relation to diamonds. The first is the shape: square, oval, and so on. The second relates to the specific quality of cut within the shape, and the quality and price will vary greatly based on the cut quality. Since diamonds are one of the hardest materials, special diamond-coated surfaces are used to grind the diamond down. The first major development in diamond cutting came with the "Point Cut" during the later half of the 14th century: the Point Cut follows the natural shape of an octahedral rough diamond crystal,
eliminating some waste in the cutting process.
Diamond cutting, as well as overall processing, is concentrated in a few cities around the world. The main diamond trading centers are
Antwerp
Antwerp (; nl, Antwerpen ; french: Anvers ; es, Amberes) is the largest city in Belgium by area at and the capital of Antwerp Province in the Flemish Region. With a population of 520,504, ,
Tel Aviv
Tel Aviv-Yafo ( he, תֵּל־אָבִיב-יָפוֹ, translit=Tēl-ʾĀvīv-Yāfō ; ar, تَلّ أَبِيب – يَافَا, translit=Tall ʾAbīb-Yāfā, links=no), often referred to as just Tel Aviv, is the most populous city in the G ...
, and
Dubai
Dubai (, ; ar, دبي, translit=Dubayy, , ) is the most populous city in the United Arab Emirates (UAE) and the capital of the Emirate of Dubai, the most populated of the 7 emirates of the United Arab Emirates.The Government and Politics of ...
from where roughs are sent to the main processing centers of India and China.
Diamonds are cut and polished in
Surat
Surat is a city in the western Indian state of Gujarat. The word Surat literally means ''face'' in Gujarati and Hindi. Located on the banks of the river Tapti near its confluence with the Arabian Sea, it used to be a large seaport. It is now ...
,
India
India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...
and the
Chinese
Chinese can refer to:
* Something related to China
* Chinese people, people of Chinese nationality, citizenship, and/or ethnicity
**''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation
** List of ethnic groups in China, people of ...
cities of
Guangzhou
Guangzhou (, ; ; or ; ), also known as Canton () and alternatively romanized as Kwongchow or Kwangchow, is the capital and largest city of Guangdong province in southern China. Located on the Pearl River about north-northwest of Hong Kon ...
and
Shenzhen
Shenzhen (; ; ; ), also historically known as Sham Chun, is a major sub-provincial city and one of the special economic zones of China. The city is located on the east bank of the Pearl River estuary on the central coast of southern province ...
.
India in recent years has held between 19–31% of the world market in polished diamonds and China has held 17% of the world market share in a recent year.
Other important diamond centers are
New York City
New York, often called New York City or NYC, is the List of United States cities by population, most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the L ...
and
Amsterdam
Amsterdam ( , , , lit. ''The Dam on the River Amstel'') is the Capital of the Netherlands, capital and Municipalities of the Netherlands, most populous city of the Netherlands, with The Hague being the seat of government. It has a population ...
.
Diamond cutting process
The basic diamond cutting process includes these steps; ''planning'', ''cleaving'' or ''sawing'', ''bruting'', ''polishing'', and ''final inspection''.
[''Diamonds and Diamond Grading: The Evolution of Diamond Cutting'' ]Gemological Institute of America
The Gemological Institute of America (GIA) is a nonprofit institute based in Carlsbad, California. It is dedicated to research and education in the field of gemology and the jewelry arts. Founded in 1931, GIA's mission is to protect buyers and se ...
, Carlsbad, California, 2002 A simplified
round brilliant cut process includes the following stages:
* Planning – Modern day planning of a diamond is done using computer software.
* Marking – Outlining the best possible shape and cut of the diamond.
* Sawing the rough stone – depending on the shape of rough diamond as not all diamonds are sawn.
* Table
* Bruting the girdle.
* Blocking 8 main pavilion facets – these facets are divided into 4 corners and 4 pavilions as the corners and pavilions run in different directions due to the atomic structure of the diamond.
* Crown – the crown consist of 8 main facets and are divided into 4 corners and 4 Bezels.
* Final bruting – ensuring the diamonds girdle is perfectly round and smooth.
* Polishing all 16 main facets.
* Brillianteering – Adding and polishing 8 stars and 16 pavilion and 16 crown halves.
* Quality control – checking for symmetry, polish and cut (angles) after the diamond is completed.
This is just one, although a fairly common way of creating a round brilliant cut. The actual process also includes many more stages depending on the size and quality of the rough stone. For example, bigger stones are first scanned to get the three-dimensional shape, which is then used to find the optimal usage. The scanning may be repeated after each stage and bruting may be done in several steps, each bringing the girdle closer to the final shape.
It is possible only because the
hardness
In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...
of
diamond
Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the Chemical stability, chemically stable form of car ...
varies widely according to the direction in which one is trying to cut or grind.
Planning
Diamond manufacturers analyze diamond rough from an economic perspective, with two objectives steering decisions made about how a faceted diamond will be cut. The first objective is that of maximum
return on investment
Return on investment (ROI) or return on costs (ROC) is a ratio between net income (over a period) and investment (costs resulting from an investment of some resources at a point in time). A high ROI means the investment's gains compare favourably ...
for the piece of diamond rough. The second is how quickly the finished diamond can be sold. Scanning devices are used to get a 3-dimensional computer model of the rough stone. Also, inclusions are photographed and placed on the 3D model, which is then used to find an optimal way to cut the stone.
Maximizing value
The process of maximizing the value of finished diamonds, from a rough diamond into a polished gemstone, is both an art and a science. The choice of cut is influenced by many factors. Market factors include the exponential increase in value of diamonds as weight increases, referred to as ''weight retention'', and the popularity of certain shapes amongst consumers. Physical factors include the original shape of the rough stone, and location of the inclusions and flaws to be eliminated.
=Weight retention
=
The weight retention analysis studies the diamond rough to find the best combination of finished stones as it relates to ''per carat'' value. For instance, a 2.20-carat (440 mg) octahedron may produce (i) either two half-carat (100 mg) diamonds whose combined value may be higher than that of (ii) a 0.80-carat (160 mg) diamond plus a 0.30-carat (60 mg) diamond that could be cut from the same rough diamond.
The round brilliant cut and square brilliant cuts are preferred when the crystal is an octahedron, as often two stones may be cut from one such crystal. Oddly shaped crystals, such as
macle
{{no footnotes, date=April 2009
Macle is a term used in crystallography. It is a crystalline form, twin-crystal or double crystal (such as chiastolite). It is crystallographic twin according to the spinel twin law and is seen in octahedral cryst ...
s are more likely to be cut in a ''fancy cut''—that is, a cut other than the round brilliant—which the particular crystal shape lends itself to.
Even with modern techniques, the cutting and polishing of a diamond crystal always results in a dramatic loss of weight, about 50%.
Sometimes the cutters compromise and accept lesser proportions and symmetry in order to avoid inclusions or to preserve the weight. Since the per-carat price of a diamond shifts around key milestones (such as 1.00 carat), many one-carat (200 mg) diamonds are the result of compromising ''cut quality'' for ''carat weight''.
=Color retention
=
In colored diamonds, cutting can influence the color grade of the diamond, thereby raising its value. Certain cut shapes are used to intensify the color of the diamond. The radiant cut is an example of this type of cut.
Natural green color diamonds most often have merely a surface coloration caused by natural irradiation, which does not extend through the stone. For this reason green diamonds are cut with significant portions of the original rough diamond's surface (''naturals'') left on the finished gem. It is these ''naturals'' that provide the color to the diamond.
Turnaround minimization
The other consideration of diamond planning is how quickly a diamond will sell. This consideration is often unique to the type of manufacturer. While a certain cutting plan may yield a better value, a different plan may yield diamonds that will sell sooner, providing an earlier return on the investment.
Cleaving or sawing
Cleaving is the separation of a piece of diamond rough into separate pieces, to be finished as separate gems. During the planning stage, diamond manufacturers identify
cleavage planes, and use those planes to decide how to split the diamond. Diamond manufacturers cut a groove in the diamond with a laser or saw, and then split the diamond with a steel blade.
Sawing is the use of a diamond saw or laser to cut the diamond rough into separate pieces. Unlike cleaving, this step does not involve cleavage planes. This step gives diamonds their initial shape.
Bruting
Bruting is the art of cutting a diamond round. In the modern era diamonds are rounded using either a laser, a diamond disk impregnated with diamonds, or two diamonds cutting against each other. Industrial diamonds can also be used for bruting a diamond round. Modern computer software measures the roundness of each diamond and ''ideal cut'' diamonds have to round within a tenth of a millimeter to qualify as an excellent cut diamond.
Diamond polishing
![Diamond Polisher](https://upload.wikimedia.org/wikipedia/commons/2/25/Diamond_Polisher.jpg)
Diamond polishing is the final polishing of the diamond. In a diamond factory, one would find a diamond ''crossworker'' who first places the main facets on a diamond (blocking the diamond). This is done to ensure maximum weight, clarity and best angles for the specific shape of diamond. After initial crossworking is complete, the diamond is finalized by smoothing the main facets by the crossworker, which is known as polishing the diamond. After the main facets have been polished by the crossworker, the final facets are polished onto the diamond by a ''brillianteer''. The facets added are the stars, top and bottom halves are also known as upper and lower girdle facets.
Final inspection
The final stage involves thoroughly cleaning the diamond in acids, and examining the diamond to see whether it meets the quality standards of the manufacturer.
Recutting
Due to changes in market desirability and popularity, the value of different styles of diamond fluctuates. All diamonds can be recut into new shapes that will increase value at that time in the market and desirability. An example of this is the ''marquise'' cut diamond which was popular in the 1970s to 1980s. In later decades, jewelers had little success in selling this shape in comparison to other shapes like the oval or pear shape. The ''marquise'' can be cut into an oval diamond by any diamond cutter with a loss of 5 to 10% in total weight. For example, a 1.10-carat marquise shape would be a 1.00 oval cut diamond by rounding the sharp points and creating an oval which currently in the market has a much greater desirability and resale value. The same marquise shape also could become a pear shape instead by only trimming and rounding the side which will be turned into the base of the pear shape.
In the 18th century there was a trend for recutting Indian diamonds to suit English tastes. The
Koh-i-Noor
The Koh-i-Noor ( ; from ), also spelled Kohinoor and Koh-i-Nur, is one of the largest cut diamonds in the world, weighing . It is part of the Crown Jewels of the United Kingdom. The diamond is currently set in the Crown of Queen Elizabeth The ...
's original cut weighed a little over 186.00 carats. When it was recut to an oval-shaped brilliant, almost 80 carats were lost.
Other aspects are affected in recutting for value as well, such as the clarity. If an original shape contained inclusions on the tips, the recut would yield an increase in clarity since trimming down to a new shape would yield a cleaner overall finished diamond.
See also
*
Cut (gems)
When a gemstone is desired to be used in jewelry, it is cut depending on the size and shape of the rough stone, as well as the desired piece of jewelry to be made. As a general rule, a cut gemstone will reduce the mass (described in the carat) b ...
*
Diamond
Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the Chemical stability, chemically stable form of car ...
**
List of diamonds
Diamond (gemstone), Diamonds become famous typically for some combination of their size, color and quality. Diamonds occur naturally in many different colors, so the largest diamond of a particular color may not be large in absolute terms, but it ...
*
Diamond cut
A diamond cut is a style or design guide used when shaping a diamond for polishing such as the brilliant cut. Cut does not refer to shape (pear, oval), but the symmetry, proportioning and polish of a diamond. The cut of a diamond greatly affects ...
**
Brilliant (diamond cut)
A brilliant is a diamond or other gemstone cut in a particular form with numerous facets so as to have exceptional brilliance. The shape resembles that of a cone and provides maximized light return through the top of the diamond.
Even with mo ...
**
Princess cut
The princess cut (technical name 'square modified brilliant') is a diamond cut shape often used in engagement rings. The name dates back to the 1960s, while the princess cut as it exists was created by Betazel Ambar, Ygal Perlman, and Israel Itz ...
*
Faceting machine
A faceting machine is broadly defined as any device that allows the user to place and polish facets onto a mineral specimen. Machines can range in sophistication from primitive jamb-peg machines to highly refined, and highly expensive, commercial ...
*
Gemcutter
Lapidary (from the Latin ) is the practice of shaping stone, minerals, or gemstones into decorative items such as cabochons, engraved gems (including cameos), and faceted designs. A person who practices lapidary is known as a lapidarist. A lap ...
*
American Gem Society
The American Gem Society (AGS) is a trade association of retail jewelers, independent appraisers, suppliers, and selective industry members, which was founded in 1934 by Robert M. Shipley.
The Society is based in Las Vegas, Nevada, along with th ...
References
{{Reflist
External links
Antique Jewelry University – A History of Diamond Cutting Marcel Tolkowsky. Web edition as edited by Jasper Paulsen.