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A Brief History of Cut Diamonds
By Gary Dutton

Diamonds, known for over 3000 years, were probably first found in India as loose stones associated with the sand and gravel of riverbeds (alluvial deposits). For centuries they were thought to posses magical powers, no doubt because of their hardness and luster, and were kept, uncut, as sacred objects or important treasures of state by the religious and political leaders of the day. Being regarded as talismans, it was thought that they would lose their powers if they were altered in any way.

It wasn't until the 11th century that diamonds were first worn, in their uncut form, as adornments. However, with the use of diamonds in jewelry, sometime in the 13th century it became known that a diamond's appearance could be enhanced by grinding and polishing [later by cleavage (below)] along the four octahedral faces (below) of the rough crystal. This was achieved by polishing with diamond dust at angles varying slightly from those of the original octahedral faces to form a point cut (below). (It had been discovered early on that the planes parallel to these faces are the hardest and can't be polished.) Point cuts were seen from the Middle Ages until the Renaissance period.

The table was the first major facet to be fashioned on a diamond crystal. Thus, the table-cut (below) diamond was formed by grinding down the top octahedral point to form a square facet using a recently discovered technique called bruting. This table facet was then finished off by polishing with diamond powder. (Bruting is the process where a diamond or diamond chip is used to wear away a portion of another diamond crystal. This method is still applied in modern cutting to form the rounded shapes of the girdles and pavilions of various shaped stones.)

Later, table-cut diamonds were further modified by adding a smaller facet to the lower octahedral point to form a culet at the bottom of the stone. These culets were often large, as much as half the size of the table, and designed to reflect light and add brightness to the diamond. (We now know that the planes of the table and culet are oriented in one of the three cubic planes of the diamond rough, which are called the sawing directions, and are known to be the softest in the crystal.)

With time, many of the older point-cut stones were converted to table cuts because of their popularity. Subsequently, table cuts themselves were further modified by adding eight narrow facets, one to each edge of the table and pavilion, in order to improve the brilliance of the stone.

A major advance in faceting came about with the introduction of the polishing wheel, or scaife, in the middle of the 14th century. This led the way for manufacturing brighter diamonds with increased facet pattern complexity. In this same era the rose cut (below) appeared. Its shape is basically flat and usually circular, with a faceted, domed top and plain bottom. This cut was well suited to the use of diamond fragments and the thinner forms of diamond rough called macles and flats. The major sources of this cut, which had many variations, were the diamond centers of Amsterdam and Antwerp, and were common until the early 1900's.

By the mid-seventeenth century the old single cut (below) emerged. This design was formed by producing a more rounded overall shape with an octagonal-shaped table and eight facets on each the crown and pavilion. This cut eventually evolved into the brilliant cut with the complete rounding of the girdle and the application of additional facets to the crown and pavilion. Today round diamonds of less than 0.20ct. (used largely as accent stones in jewelry), called melee, are frequently cut as single cuts because smaller stones require fewer facets.

The term "brilliant-cut" was coined at the end of the 17th century and was represented by several forms of faceted diamonds based on the shape of the commonly found octahedral form of the rough crystal. These cuts were round, rounded or cushion-shaped in girdle outline. During the early 18th century, Brazil, the new center of world diamond production, gave rise to the cushion-shaped old-mine cut (below), a forerunner of the modern brilliant cut having 33 crown and 25 pavilion facets, the same 58 facets as today's round brilliants. These cuts are still seen in some older estate pieces.

With the 19th century came the rounded cuts like the old European cut (OEC, below) and the English round cut (not shown), both of which also have a total of 58 facets of the same type as today's round brilliants. Old-mine and old European cuts are deep-cut with small tables and relatively large culets, whereas the English round cut has a shallower crown and pavilion and larger table. Theses cuts are still commonly seen in estate jewelry of that era.

The early modern Tolkowsky brilliant cut (below) emerged with Marcel Tolkowsky's published thesis entitled, "Diamond Design: A Study of the Reflection and Refraction of Light in Diamond", in 1919. This was a theoretical work describing the best proportions of a round brilliant diamond which would provide a balanced return of light (brilliance) and dispersion. As a result, many cutters were led to fashion many of the larger, high quality goods in the range of these proportions. These proportions are also sometimes called the "American Ideal Cut", even though the work originated in Europe. Subsequently, the American Gem Society adapted proportional ranges for their "Ideal" (zero, 0, best) cut grade, based on this work and they are still used today. (For a detailed description of the meaning of what is an Ideal Cut round brilliant diamond, please read our Free Article on this subject.)

Today's modern round brilliant (below) cut diamond, produced largely since World War II, differs in several ways from the Tolkowsky cut. The Tolkowsky brilliant had a larger culet, visible through the table, whereas today's round brilliant has either no culet, or a very small or small culet. Also, the table size range is larger in today's round cuts (about 53-57%, as a % of the stone's average diameter), but still include Tolkowsky's calculations which called for a 53% table. Finally, the lower girdle facets are now cut much deeper (about 75%) down the pavilion compared to earlier patterns, where they were cut to only about 1/3 of the pavilion depth.


CUT IS KING!
Now that you have a little insight into the history of diamond cuts, remember that it is largely the quality of the cut, which releases the beauty of the diamond to your eyes. Thus, the most important guideline to remember when selecting any diamond is, "Find the stone with the best cut quality you can afford." In short, "CUT IS KING!", for it really doesn't matter if you have chosen a stone with D color and Flawless clarity, if it is not well proportioned, you will forever have a dull, lifeless looking diamond! On the other hand, if you select a diamond which appears colorless to your eye (usually D to I color) and whose inclusions you can't see with the naked eye (usually Fl to SI1 and sometimes SI2) and then go for the best cut quality you can afford, you will have a bright and lively diamond forever!

For the round brilliant, there are ranges of proportion and grades of finish (polish and symmetry) which are widely recognized as "Ideal" by the trade and are part of the grading system of the American Gem Society (AGS). These criteria can also be applied to diamonds graded by the Gemological Institute of America (GIA), which doesn't offer a cut grade in their report. These criteria require that GIA-graded diamonds have polish and symmetry grades which are "excellent", and that the proportions fall within the AGS Ideal (or zero) ranges as measured by a proportion analyzer called a Sarin instrument. It is important to make sure that you have this information before selecting a diamond.

Dutton's Diamonds specializes in Ideal cut AGS0 (sometimes erroneously called AGS triple zeros) and GIA Ex/Ex branded and unbranded round brilliant diamonds (many with Sarin reports). These diamonds are cut to superior proportions and finish, giving you the best in brilliance, dispersion and scintillation. And as a final bonus, many also show the coveted Hearts & Arrows pattern, which is the mark of outstanding cut symmetry!

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Gary Dutton, Ph.D., G.G.
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