History of the Round Diamond Cut

DIAMOND CUTTING STYLES

Diamond is a mineral made of essentially pure carbon.  It is the only gem made of a single element.  This pure carbon crystallizes in an isometric or cubic structure.  Most diamonds in the rough are in the form of an octahedral crystal.  You could picture this as two four sided pyramids stuck together at their base.  Diamonds are typically cut in an effort to maintain as much of the original rough diamond weight as possible.  A prime example of this is the Old Mine Cut.

OLD MINE CUT

This cut was originally developed in the early 1800’s and probably used well into the 1870’s.  These diamonds were cut solely by hand in the beginning.  Steam power enabled diamond sawing and sped up the cutting process around the 1840’s, however most of the cutting was still done by hand – and the public still preferred the Old Mine Cuts.  The Old Mine Cut diamonds most notably possess a cushion shape as a result of maximizing the octahedral outline, and retaining weight.  Along with the squarish outline this cut typically had a very small table, open or large culet, and often very clumsy symmetry.  These extreme variations in angles and proportions resulted in diamonds ranging from very brilliant to very blocky light return, and fishy, watery and sometimes dead appearances.  It could be said that this gave each diamond a unique personality and distinct beauty just as the bygone era in which they were fashioned, compared to the cuts of today.     

EUROPEAN CUT

Sometime around 1875 the steam-powered lathe, invented by Charles Field, considerably sped up the cutting process and made it much easier to cut a round girdle outline.  About this time the European Cut had emerged and continued into the 1920’s.  Older European cuts were still quite lumpy, probably due to a transition in cutting style from the Old Mine.  There are diamonds out there that are clearly transitional cuts exhibiting influences from both cutting styles.  The European cut typically had a table sometimes as small as 45% up to 57%, a high crown, a large culet, and a thin girdle.  It is common to see chipping around the girdles of these older stones.  The biggest visual difference between the Old Mine and the European is the change to a round outline and a much more symmetrically balanced cut, which improved toward the end of the this cutting style.    
 

TRANSITION CUT

Also known as the Early American Cut and the Early Modern Cut, this style had a lower crown, more medium table, shorter pavilion and smaller culet.  Girdles were not faceted yet.  The most significant diamond cutter of the time was Henry Morse, perhaps the first person to begin to consistently cut diamonds into shapes that were different from the prevailing European cuts.  Morse and his partner Charles Field cut diamonds with smaller tables, shallower crown angles, and smaller culets than the European Cut. Rather than cut diamonds only to retain weight, Morse and his cutters attempted to cut every diamond to fairly consistent proportions.  Morse most likely found through practice what Tolkowsky would attempt to determine mathematically.  This cutting style is seen from around 1918 through the mid to late 1920’s.

MODERN CUT

In 1919, Marcel Tolkowsky described in a book entitled "Diamond Design" a specific mathematical computation of angles and proportions that would allow maximum brilliance and dispersion of all light striking a diamond.  His formula includes the following:  Given the diamond’s diameter to be equal to 100, the table should be 53%, total depth 60 to 61%, crown depth 16.2%, and pavilion depth 43.1%.  Also ideal crown angle should be 34.5° and optimum pavillion angle 40.75°.  This new cutting style was becoming increasingly popular in his time, especially in America. Different versions of this style would become known as the Tolkowsky Cut, the Modern Brilliant Cut, and the American Ideal Cut. Although Tolkowsky wasn't the first to suggest diamond proportions in these ranges, he was the first to publish a mathematical foundation that supported them.  These proportions might not have been too different from those that had been used by Morse and others in America.  Along with the Transition Cut, Tolkowsky’s cutting style led to different appearances than those of Old European and Old Mine cuts that were prevalent at the time.

Unfortunately these proportions proved to be quite expensive to produce.  This led to more spread stones with tables sometimes reaching 65% and larger as most cutters would cut a diamond to retain maximum carat weight regardless of the proportions, while still attempting to produce a brilliant diamond.  For many years very few cutters were cutting the recommended 53% - 57%  table.  The majority of cutters were cutting table sizes larger than 60%.  Plus the majority of the buying public seemed to prefer the 60% tables as this gives the appearance that the diamond is actually larger even though the beauty is somewhat diminished.

In the past twenty years the public seems to have become more educated.  More and more consumers are expecting a diamond certificate with their significant diamond purchases, and more often are interested in better proportions.  Diamonds are being cut today more frequently within what’s become the Ideal Cut range.  It is rare to find a diamond that meets Tolkowsky's original standards, however the Ideal range for a round brilliant diamond typically would include a depth of 59% to 61% and a table of 53% to no more than 59%. These proportions theoretically will handle most of the light that enters the surface of the diamond's crown and return it with maximum brilliance and dispersion to the observer's eye! 

But Wait!  The Gemological Institute of America recently concluded a study that encompassed 15 years of intensive research of more than 38 million proportion combinations and over 70,000 human observations on 2300 diamonds to prove that there were many proportion combinations other than Tolkowsky’s that potentially provided maximum brilliance and dispersion.

New Round Brilliant Diamond Cut Grade

The proportion formula, originally described by Marcel Tolkowsky in the year 1919, was purported to allow maximum brilliance and dispersion of all light striking a round brilliant cut diamond.

From my perspective of selling diamonds for more than 28 years, the most common downside to a consumer who focuses on finding a diamond with these exacting proportions is that he or she has forgotten the most basic premise of buying a diamond:  beauty and romance.  If you get so completely caught up in the numbers you tend to analyze and worry yourself throughout the whole diamond shopping experience and forget that it all comes down to how brilliant and pleasing the diamond is to the eye and even more importantly that it is a symbol of your unending love and devotion. 

I have seen hundreds of diamonds over the years that did not fit exactly into the Ideal Cut mold yet were incredibly beautiful, brilliant diamonds.  Apparently so have the Gemologists and Scientists at GIA. 

GIA began a study in 1989 using a computer model to determine how light behaves within a round brilliant cut diamond.  They only recently concluded that 15 year study, at a cost of millions of dollars, involving intensive research of more than 38 million proportion combinations and over 70,000 human observations on 2300 diamonds. 

Essential findings as reported in the Fall 2004 Gems & Gemology include:

Proportions need to be considered in an interrelated manner.  The combination of proportions is more important than any individual proportion value.
Attractive diamonds can be manufactured in a wider range of proportions than would be suggested by historical practice or traditional trade perception.
Personal preference still matters.  Diamonds with different appearances can be found within each cut grade, so individuals need to look at the diamond itself, not just its grade, to choose the one they like the best.
The conclusion of this study provided GIA with the knowledge that there are many different sets of proportions for top grade diamonds and an even wider set of proportions for very pleasing upper grade and middle grade diamonds. 

As a result GIA has developed a new cut grade system that considers the combination of seven components: brightness, fire, scintillation, weight ratio, durability, polish and symmetry.  This new cut grading system includes five grades: EXCELLENT, VERY GOOD, GOOD, FAIR, and POOR.  The new GIA Diamond Grading Reports will include an overall cut grade of the diamond and expanded proportion information.

What does this mean to you?  You should know what you are buying when shopping for a diamond.  The four C’s, Cut, Color, Clarity, and Carat Weight, remain the best way to compare diamonds. The new expanded cut grade system gives you a better understanding of the overall beauty of a given diamond from a grade of Excellent to Poor.  Use this knowledge in combination with the Color, Clarity and size you are interested in to make your decision.  But most importantly – after you have considered all these factors you should simply choose the diamond that you like the most!

Perry's At SouthPark, Not your typical jeweler!