The physicochemical composition of the diamond makes it possesses particular optical properties, which with its hardness have helped to make it an exceptional precious stone and certainly the most coveted until today.

Possessing a high index of refraction and a strong dispersive power, the diamond sharply diverts the light penetrating it and disperses this light in a rainbow of color as do drops of water to produce the rainbows in the sky.

diamond cut

Photo showing diamonds of similar diameters, one raw and the other two cut. The best cut diamond on the left appears to be the largest while it is actually the lightest, its weight expressing itself in carat. (source photo)


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The quality of the diamond's cut and polish has a great influence on the brilliance of the diamond, the brilliance called "diamond fire" and on the colors returned by it. Of the 4 quality criteria of diamond, the cut quality depends directly on the diamond cutter and is an important factor on the visual aspect of it.

While diamond buyers often focus on the weight, purity and color of the diamond, it's the cut quality that determines its brilliance.

Different shapes of diamond cuts

The different shapes of diamond cuts are presented in the following diagram :

shapes diamond cut

The most popular form of cut is the brilliant round cut that of all, is the one most studied by scientists and diamond dealers.

If the diamond is used and carved for centuries by men to crimp it on jewels, it wasn't until 1919 and the work of Marcel Tolkowsky to discover a "perfect" diamond cut exploiting its brilliance at best.

Diamond anatomy

This brilliant round diamond cut includes 58 facets including the culet. (source photo)

In the past, the diamond cuts were far more simplistic and didn't exploit the brilliance of the diamond at all, so that some old cut diamonds look darker than they are brilliant. To learn more about the subject, I advise you to read this article on old cut diamonds.

Ancient diamonds cut

Ancient diamond cuts (source photo)

Diamond cut quality 

If cutting gives shape to the diamond, it's also and above all it determines the quality of the diamond's interaction with the light, maximizing (or not) its brilliance which is so sought after.

The shape, ie the pavilion depth and the angle of the facets determines the behavior of the light inside the diamond, thus making it possible to maximize the light re-emitted by the table facet or allowing it to escape through the sides of the diamond.

diamond cut

Gemology laboratory GIA has developed a classification scale of the diamond cut quality that refers to all.

GIA scale qualityQuality scale of the diamond cut, identical to that of polishing and symmetry.

Other criteria intervene to judge the quality of a diamond, these criteria are the polishing, the symmetry of the diamond which are also part of the cut process carried out by the diamond cutter.

How are the diamonds cut ?

This is indeed a very good question.

Diamond being the hardest known material, how can it be cut and shaped ?

Traditional techniques use diamond cleavage planes to "break" the rough diamond with a well-located impact, creating two rough diamonds with a flat surface. Each will then be cut using diamond slurries with diamond powder.

It's a long and expensive process that is very well explained through these videos that I invite you to watch. These reports are well done and you'll see enough to understand how are cut diamonds.


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You'll discover all you need to know to buy diamonds jewelry online or in store.
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August 06, 2019 — Hugo Maherault

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