A Story of Diamonds: Cutting a Round Brilliant

A special thanks to Andrea Robinson, who had provided us with this article on The Story of Diamonds, which was originally written and published at 

starvingartiststeam.blogspot.com

First, the planner starts with a diamond crystal.  The planner decides what is going to happen with the crystal.  One stone, two, three, what shape?

The marker then marks where the diamond needs to be sawn or cleaved.

If the diamond is to be cleaved, a kerf (small groove) is cut into the crystal with a laser.  Then, some extremely skilled person gets to whack it with a mallet.

The crystal is more likely to be sawn, these days.

The next step is bruting which rounds out the stones and gives the initial cone shape to the pavilions.  In this step, two diamonds are used to shape each other.  This can be done by hand or machine.

Next, the diamond is blocked.  The table plane is cut, and the pavilion mains and crown facets are placed.  The brillianteers then add the remaining facets and do the final polishing.

This video shows most of the process:

A Story of Diamonds: Marcel Tolkowsky and the Modern Brilliant

A special thanks to Andrea Robinson, who had provided us with this article on The Story of Diamonds, which was originally written and published at 

starvingartiststeam.blogspot.com

The Modern Brilliant was born in 1919 from the mathematical calculations of Marcel Tolkowsky.  As a member of a family of Belgian diamond cutters he had a certain interest in making beautiful diamonds.  As an engineer, he studied the way light behaves within a diamond and determined the combinations of angles, facet sizes and shapes needed to maximize both the fire and brilliance that a diamond displays.
 

Fire is the term applied to the spectral colors reflected out of the heart of a diamond.  Brilliance is the amount of light returned to the viewer.  Sparkle, or scintillation, refers to the combination of these two factors.

 

He determined that if a diamond is cut too deep or too shallow, light will leak out and the diamond will not be as bright or fiery as it could be.  Moreover, the shape and size of each facet is important to the amount of light returned to the viewer.

 

The Modern Brilliant cut consists of 58 facets, or 57 if the culet is excluded: 33 facets on the crown and 25 (or 24) on the pavilion.  Contemporary diamonds are usually cut without a culet.

Tolkowsky's model is the basis of every new round brilliant cut.  Over the years, advances in science have allowed us to refine these guidelines into spectacularly sparkly diamonds.  Some, like the Hearts and Arrows cut, rely on exacting specifications regarding pavilion and crown angles, table size, girdle thickness, facet sizes, and alignment.  Alignment refers to how well the crown and pavilion line up.  Perfect alignment is when, at the girdle, the points of the kite and crown facets match up with the pavilion mains and lower girdle facets.

 

You can see in this next image that the precise cutting is somewhat visible in the finished stone without the special viewer.  The red viewer images show that the cut is not exactly perfect, as the hearts are not uniform and the arrows are a little off.

 

This fancy vivid yellow is a stunning example of excellent cutting by Eight Star, the company that pioneered the Hearts and Arrows cut.

Next time, we see how a round brilliant diamond is made.

A Story of Diamonds: Cuts through the Ages - Old Mine Cut

A special thanks to Andrea Robinson, who had provided us with this article on The Story of Diamonds, which was originally written and published at 

starvingartiststeam.blogspot.com

The next metamorphosis in diamond cutting proved even more brilliant than the last.  By tripling the number of facets, diamond cutters released more brilliance and fire from the depths of their diamonds than ever before.  It also preserved a good deal of the weight of the original crystal.

The girdle profile still mimics the squared shape of the crystals these were fashioned from.  You can see, also, the form of the single-cut before it was embellished with extra facets.  In the diagram below, I have colored the new facets pink.

The proportions are different, but this cut possesses all of the facets of the modern round brilliant as shown in this diagram:

The Old Mine cut is deep with a small table and often squarish in shape.  The depth allows light to leak out of the gem, so they are less bright than modern stones.  The facet arrangement and small table, however, encourages a good deal of dispersion which is the breaking up of light into spectral colors.  You might call this fire.

A couple more things worth noting about antique diamonds: because these were fashioned from well formed octahedrons, the clarity is often quite good.  The Old Mine is also the precursor to modern cushion cuts.

The Starving Jewelry Artists do not endorse the Three Graces in any way, the website just happen to have a lovely collection of fascinating specimens.  You may click on the images to visit their website for more information on these antique jewels.

Edwardian earrings set with blue moonstone and old mine cut diamonds:

Edwardian pendant set with old mine and old European cut diamonds and a pearl:

A very unusual piece - portrait diamond surrounded by old mine cut diamonds and emeralds: