The first great name in European diamond cutting is Louis de Berquen. Certainly the first regular cut was the table cut. It was originated in India and one point into a table and the opposite point into a smaller table called the culet and then grinding the four ribs above the girdle to provide facets on the upper part the crown and the four below to form facets on the lower part, the pavilion.
Another cut that tended to follow the shape of the rough was the rose cut. Flat underneath the upper and convex part was covered in facets: twenty four for a Holland rose, eighteen to twenty for a Half Holland and six to eight for an Antwerp rose. There were many variations on the cut, largely depending on the shape of the rough. A Double Rose was a diamond faceted in a dome on both sides, the first use of which is attributed to Louis de Berquen, when he cut the Florentine for Charles the bold. Rounded stones were suitable for a bead cut and pear shaped ones would become pendeloques.
One of the earliest faceted cuts which marked a step toward the modern brilliant was the Mazarin cut named after Cardinal Mazarin of France in the mid seventeenth century. It was a cushion shaped cut with 17 facets above the girdle and 17 below but it still lost a great deal of light through the bottom and the sides. A later variation called the triple cut or the old mine cut was the immediate precursor of what we know as the modern brilliant.
The brilliant cut or round cut diamond is deservely popular as a result of its brilliance its regular shape and standardization and because most rough diamonds lend themselves to the cut with an average weight recovery of the order of 50 present. But it is not the only cut. Approximately 2 present of rough diamonds, because of their shape or flaws, cannot be cut into a round brilliant without an unacceptable loss of weight. It is these stones that are cut into the shapes known as marquise, pendeloques (pear shaped) oval, emerald, triangle & square cuts. As a group these are all classed as fancy cuts. The pendeloque is far and away the most rare. These cuts are more expensive than the ordinary round brilliant cut because their cost of manufacture is high but higher weight recovery should be more than compensate for this factor. The emerald cut is used for long rough diamonds and although weight recovery is above average at approximately 60 present, the cut sells at up to 25% less than a round brilliant because its long parallel facets fail to show the same degree of brilliance.
Processes done on rough diamonds or gems:
There are five processes used in the creation of a polished gem from the rough:
splitting a stone along the cleavage plane. The art of the cleaner has always been regarded as the greatest talent in the diamond cutting industry.
dividing a crystal by using a diamond saw. Clean regular octahedral are normally divided by sawing. The diamond cutter is said to “saw grain” that is he cuts in a non-cleaving direction.
shaping a diamond by removing part of it by rubbing against another diamond. The next step is to shape the sawn or cleaved stone into a circular outline. The result of this very skilled operation should be a diamond with a perfectly rounded girdle set exactly parallel to the table. The diamond used as a tool is usually itself a rough and will be bruited in its turn.
4. Grinding or Blocking
Making a flat surface by holding the crystal against a rotating wheel applied with diamond powder. First he grinds the table of the diamond and then a crown or bezel facet between the girdle and the table. The stone is then turned over and four pavilion facets are ground below the girdle. These eight facets are followed by four more on the crown and four more on the pavilion.
5. Brillianteering or Polishing
Preparing the finished gem by a more refined application of grinding techniques. The brillianteerer completes the whole operation by adding the remaining forty facets. First he cuts eight star facets where the crown facets meet the table and then 16 girdle facets where they meet the girdle. Finally he cuts two long facets called halves into each of the pavilion facets. All the facets are then polished.