Cutting and Polishing

Once the rough diamonds are sorted, they are sent off to be cut and polished. Despite the importance of this step in the diamond’s final appearance, according to a 1997 GIA study the cutting and polishing step contributes the least to the cost of manufacturing. The figure below illustrates the manufacturing cost of a diamond worth $100. While the cut and weight of the diamond will have the largest impact on the diamond’s cost, the actual mark-up from this stage is only about 2% of the final value (Caspi, 1997).



The remaining processes can be split into four steps: marking, cleaving/sawing, bruting, and polishing.


This is arguably the most important step in determining the diamond’s final worth. This step decides where the rough stone will be sawed or cleaved, a decision that determines the rest of the manufacturing process of the stone. Since a diamond’s final worth is largely influenced by its weight, properly marking the most advantageous place to cut so as to maximize the final weight and  shape of the diamond is crucial and is often done by only the most experienced cutter or specialist (Caspi, 1997).

Right-wrong decision

In modern times, computer programs offer great insight into the possibilities of where to mark, and markers rely heavily on these programs.

Modern-Diamond-Cutting-and-Polishing (1)


Based on the shape and inclusions of the rough diamond, a manufacturer will choose to either “cleave” or “saw” the diamond (Caspi, 1997). Both processes split the rough stone into two or more parts, but cleaving is done along a different grain orientation than sawing. Both mechanical or laser cutting can be used in this step. Computers often guide both forms of cutting, although mechanical cutting (or using a diamond-bladed edge as opposed to a laser) is still sometimes done manually. Laser cutting is faster and more efficient, but is also more expensive.


The bruting process is when the diamond finally begins to take its finished form. In order to do this, two diamonds are spun against each other along computer-determined axes of symmetry, wearing away at each other until the desired shape is achieved. Before computers, this process was long and arduous as the bruter had to stop frequently to adjust the stones and the axes of symmetry based almost solely on trial-and-error (Rudnicka, 2010). With the advent of new technology, however, it is largely automated and relatively unsupervised.


In the polishing stage, the polisher uses a tang and a scaife to polish facets onto the cut stone. The tang holds the diamond in place while the scaife spins to wear away the stone into the facets, as shown in the figure below (Caspi, 1997). This stage was also once done manually but now relies heavily on computers to produce proper size, angle, and symmetry of the facets.


The Changing Face of the Cutting Industry

Traditionally, diamonds were cut in only a handful of cities around the world: Antwerp, Amsterdam, Johannesburg, New York, and Tel Aviv. Recently, however, due to low labor costs, there has been an increase of diamond cutting centers in Thailand, China, and India. Surat, India in particular has grown to cut and polish an estimated 92% of the world’s diamonds, according to a 2009 NBC report. Anymore, it is rare for diamonds less than 10 carats to be cut in traditional diamond-cutting cities like Antwerp or New York (Hussain, 2009).

India’s rise in the diamond cutting industry is due in part to its large, well-trained, yet cost-efficient workforce. When compared to China’s manufacturing cost of $17 per carat and South Africa’s $50 per carat, India’s $10 per carat gives them an undeniable advantage in the global diamond manufacturing industry (Wharton School of University of Pennsylvania, 2011). Many diamond producing countries are moving to in-house manufacturing, however, which has the potential to pull India back in the global race since India mines no diamonds of its own. In response to this, India is reaching out to countries such as Angola, Canada, Ghana, and Russia to create a more direct flow of rough diamonds into India. Currently, most diamonds go through Tel Aviv or Belgium before reaching Indian cutting centers (Hussain, 2009).

In many ways, this rising sector is incredibly beneficial to India’s economy. Roughly 500,000 jobs have been created in Surat alone, allowing many people in more rural areas to rise above the poverty line–an opportunity they otherwise may never have gotten (Hussain, 2009). The average diamond cutter makes up to five times the average per capita income. Training in diamond cutting offers otherwise unskilled laborers a highly sought after and marketable skill. The globalization of the diamond industry also encourages India to adopt more cutting edge technology and to improve their business practices.

But while all of these developments are good, there is a shadowy side to diamond cutting in India. Because diamond cutters need to have good eyesight and nimble fingers, child labor has become common in the industry despite national laws against it.Diamond factory Furthermore, workers from rural areas live in small bunk-houses or in the factories themselves, a hazardous practice that results in a number of accidents.And while reports claim that workers make much more than the average income, there is some question as to whether these reports are accurate. Even so, workers only make about $50 U.S. dollars a week (Hussain, 2009). Finally, mass diamond cutting can have negative impacts on health. Aside from the danger of the cutting instruments, air filtration systems are often inadequate and fail to remove all of the carbon particles produced by cutting and polishing the diamonds.

Former centers for diamond polishing and cutting, such as Israel and Belgium, have lost much of their business to eastern-based industries. Twenty years ago, Israel’s diamond industry employed 25,000-35,000 people. Now it employs less than 1,000 (Wharton School of University of Pennsylvania). Antwerp, traditionally the best diamond-cutting city in the world, is also being outsourced by India in particular. The number of polishers in the city has fallen from 20,000 to a few hundred now that almost all small diamonds are polished in India and Antwerp is left with only the largest, most expensive stones (Hussain, 2009). Neither Israel’s nor Belgium’s diamond industries are in any danger of collapsing because of this recent shift, but in order to cope with the changing market many companies are now moving or setting up new centers in India, China, and Thailand, further increasing the globalization of an already global industry.


The globalization of diamond cutting and polishing, specifically in recently industrialized areas, has also led to an increase in illegal diamond trade, money laundering, and tax evasion as newer industries ignore or are incapable of handling the increase in crime. Due to the complexity of the commodity chain, the international community also struggles to guard every aspect of diamond production and enforce justice.

Nevertheless, as the industry modernizes and its practices continue to become more ethical and beneficial to local and national communities, the diamond industry brings a lot of hope to developing countries and their futures.



One thought on “Cutting and Polishing

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