Rough to Polish

A raw diamond appears unimpressive when it is initially discovered: a clear pebble or rough crystal damaged by its journey from deep under the earth's crust. The diamond cutter's art is required to release the diamond's brightness, fire, and scintillation. The process of turning a raw diamond into the glittering stone on your ring finger is surprisingly complicated, requiring decades of technological advancements.

 

Diamond Cutting Through the Ages

​Diamond is the most difficult jewel to cut because it is the hardest substance on the planet. Diamonds couldn't be polished until the 15th century, when it was found that they could be polished by their own dust. Before that, the only way to wear this jewel was in the form of diamond rough and polished crystals. The potential for sparkle was awakened via faceting.

The scaif was designed in 1475 by a Flemish cutter named Lodewyk van Berquem: a diamond polishing wheel coated in oil and diamond dust with an arm above it to hold the diamond. He could not only polish diamonds but also cut facets and generate brilliance with this particular cutting wheel.

Cutters continued to innovate after discovering the brilliance of faceted diamonds, beginning by polishing crystals, then cutting off the top of the crystal to create a table cut, and finally step cuts. Faceted rose cuts were invented in the 16th century.

Mazarins, the first brilliant cuts with additional facets to maximum brilliance, were created for the French court of Versailles in the middle of the 17th century. The mine cut was developed in the eighteenth century to optimize the weight and beauty of cut gems made from diamond crystals newly available from Brazilian mines. Brazil became the "old mine" when diamonds were discovered in South Africa. The cushion shape of an old mine diamond is rounded square with a high crown and deeper pavilion, similar to the shape of an octahedral diamond crystal.

Then, in the late 1800s, the industrial revolution changed diamond cutting forever. The round diamond was formed as a result of new steam-powered machinery and motorized saws that allowed cutters to shape gems like never before. The Old European and English round cuts each have 58 facets, which is the same as today's round brilliants.

Cutters have tweaked the proportions and angles over the years to increase light output. Marcel Tolkowsky, a young Belgian student studying match in London, wrote Diamond Design, his thesis on the perfect proportions for round brilliant diamonds, in 1919. His work established the foundation for the contemporary round brilliant and the ideal diamond dimensions that are still appreciated today, despite the fact that his calculations overlooked the girdle and needed to be rectified.

 

The Diamond Cutting Process in Steps

Rather than being cut by hand, diamonds are increasingly being cut in sophisticated factories using high-tech equipment. The majority of large diamonds, as well as practically all little diamonds, are cut in India. Israel, Belgium, and China are also key cutting centers.

The majority of today's cutters labor for relatively little margins, only one or two percent. To ensure that each piece of rough is cut to unlock the best possible value, old-fashioned expertise is required.

Diamond rough has a 30 percent yield, which indicates that a one-carat rough diamond will cut a one-third carat polished stone. The majority of gem-quality diamonds mined each year are polished away as dust during the cutting process.

Sorting the raw, planning for manufacturing, cleaving or sawing the rough into a preliminary shape, shaping the girdle, and polishing the facets are the five fundamental phases in cutting a diamond. The value of the finished polished gem is influenced by decisions made at each stage of the process.

To appraise diamonds for sale, they are categorized by hand and machine into groups based on form, size, color, and clarity after they are mined. Experts separate rough diamonds from the mine into 12,000 different value categories at De Beers' world-leading diamond sorting facility in Botswana, which examines them in diffused sunshine.

The manufacturing process varies depending on the type of rough: makeable rough, which will be polished into a single stone; sawable rough, which will be sawn in half before polishing; near gem or cleavage rough, which will be cleaved into two or more pieces before polishing; and last (and least) industrial grade diamond rough, which will be cut into tools or crushed into powder.

​

Cutting Diamond Rough Evaluation

​The most complicated step in the diamond cutting process, as well as the step that demands the greatest experience and technology, is analyzing the diamond rough. Should you cut a single huge round that will sell for a higher price per carat but will waste more rough? Two smaller pears that sell for less money but produce less waste? What will provide you with the highest return? What is the current market value of all of the gems that could be made from this rough?

The marker, a highly trained cutter who weighs all the variables and determines whether a diamond should be sawn or cleft into pieces, then marks exactly where the cuts should be made, performs these complex computations. This phase can take months when dealing with huge, costly stones.

Today, advanced three-dimensional scans from Sarine machines are used by diamond cutters to produce precise measurements, three-dimensional visualization, maps of inclusions, and estimates of the final gem's color and clarity. Cutters can compare the size and quality of gems that can be cut from each piece of rough with incredible precision thanks to the scan.

There is no room for error once the cutting begins, regardless of the form chosen by the cutter - round, princess, emerald, pear, heart, marquise, oval, or baguette.

​

Diamond Rough Sawing or Cleaving

​If the goal is to cut multiple jewels from the rough, the diamond must first be sliced into pieces.

Do you remember those ads where a cutter smashes a raw diamond in half with a chisel and a hammer? This is known as cleaving: diamond crystals contain a grain, and a well-placed impact can cause the diamond to shatter between the crystal's planes. Going against the grain, on the other hand, is extremely tough. Cutters utilize a circular saw with diamond dust for hours on end to cut against the grain, or, increasingly today, a laser, which can quickly burn through a diamond.

​

Making the Diamond Form

​Following that, a process known as bruting or girdling is used to form the shape of each gem's final outline. A computer-controlled bruting machine spins diamond against diamond to create a round diamond.

The contour of a fancy shape takes longer to create than a round diamond. The heart-shaped diamond, with its varying curves and deep chasm, is the most difficult to create.

Faceting and polishing are the final phases in the cutting process. Each facet is ground into the diamond by holding it in a tang against a spinning wheel covered in diamond powder called a scaif or scaife. The process is repeated for each facet, with the diamond being moved and angled precisely to keep it completely symmetrical.

Faceting used to be done by hand, but computers now play a big role in determining the size, angle, and symmetry of each facet. Precision is essential to the beauty of the final gem since an error in the angle or positioning of a single facet might result in light leaking out of the gem instead of being reflected back to your eye as brilliance.

After that, the diamond is polished with fine diamond powder to smooth the facets, erase any polishing marks, and ensure that each facet reflects light evenly.