GEM DIAMOND MANUFACTURING (CUTTING, POLISHING)

 

 

STAGE ONE

At first the experienced staff at OUR CENTRE inspects the rough diamonds we have purchased. They determine exactly how to maximize the beauty and value of each stone through the polishing process. The polishing process begins with determining the ideal shape and size for each diamond. Windows are usually polished on the girdles of the rough crystal in order to locate any flaws, spots or knots. Our expert designer marks the stone with India ink to show where it should be cut.

 		  


 

  STAGE TWO
The decision has been made, the stone is marked and now it is ready for sawing.

The marked diamond is mounted into a special holder located at the end of the machine's arm so that the diamond rests on the sawing disc.

Diamonds are machine cut by a very thin disc (0.014-0.024 inches) forged from a special bronze alloy. Since no material is harder than a diamond, ground diamond powder must be applied to the edge of the disc so that it will cut the stones. A driving belt turns the sawing blade at the speed of about 5,000 R.P.M., while the diamond rests atop the spinning disc.

A sawer tends a bank of machines and keeps a close watch on stones being sawed, examining them carefully with a lens throughout the procedure.

 
  STAGE THREE
BRUTING

The bruting machine works on both sawed and whole stones. It shapes them into a circular outline, removing the edges yet retaining as much as possible of the original rough diamond. This process requires 2 diamonds, one diamond must be used to brute the other.

 

 

  STAGE FOUR
The bruted diamond is placed into a dop or holding arm for the final stages of polishing. The polisher rests the dop against a polishing wheel, which is made of a cast iron disc coated with diamond paste, and spinning at 2500 R.P.M. While the stone is on the wheel, he closely inspects the diamond every few seconds, constantly readjusting and aligning the dop angles to ensure polishing precision.

 

IMPORTANT POINTS TO ENSURE THE BEST CUT

Checking the Pavilion Angle
The most important angle on a diamond is the pavilion angle. This angle must be exact to properly reflect back to the eye the light which enters the stone. This light will exit the fashioned stone as brilliancy, dispersion, and scintillation- the qualities of diamond that we most appreciate. It is for this reason that the pavilion angle is constantly checked for precision.

 
The Blocked Pavilion
The blocker may choose to facet either four or eight pavilion facets before working on the crown. If he decides to make only four facets at this time, the cutter will complete the remainder after making four crown facets.

This dopped stone exhibits a completely blocked pavilion with eight facets. These will eventually be called pavilion mains.

 
First Crown Facets
This stone exhibits its first crown facet. These facets are the only ones that touch both the table and the girdle, and will later be called bezel facets. All eight crown facets will be made at this time, or only four, leaving the remainder to be placed after the completion of the pavilion.

Notice the dop that is holding the diamond during this sequence of the fashioning operation. It is very different from the one that holds the stone for the cutting of the pavilion. A great variety of tools will be needed before the completion of this diamond.

 
Checking the Crown Angle
Diamond cutting is a very exacting craft that demands constant attention. The blocker uses a simple gauge to check the angle of the crown facets, but he relies equally on his expertise and judgement. The angle must be correct for maximum dispersion- the ability of a stone to break up white light into its many spectral colors.

 
The Blocked Diamond
With 17 or 18 facets, the diamond has assumed its basic outline. But more work remains to bring out the full potential of this beautiful gemstone.

 
Rondisting
At this point, the blocked stone will probably have a girdle that is too thin. To correct this potential durability problem, the girdle may be enlarged by a second bruting, called rondisting. The cutter will try to produce a very smooth girdle, one that approximates the look of waxed paper. There may then be a second polishing or lapping of the blocked facets to bring out the superior polish of diamond.

 
Polishing Directions
To polish diamond, a cutter must take into account the hard and soft directions. Other gemstones have such directional hardness, but it is not nearly as important as in diamond, the hardest of all substances. Without an adequate command of this information, the cutter could never expect to fashion a diamond.

This slide shows the polishing of directions of a stone with its table cut parallel to a cube face. This is called a four-point diamond. If the table were cut parallel to another face, these arrows would be pointing differently.

 
Brillianteering
An important feature of fashioned gems is the play of light off the numerous facets, a quality called scintillation. To take advantage of this, the brillianteerer adds a complement of 24 more crown facets and 16 more pavilion facets as a finishing touch.

 
Brillianteering the Crown
The brillianteerer first grinds eight triangular-shaped star facets around the table, as he has started to do here. Eight pairs of upper-girdle facets around the girdle will follow to complete the crown. In contrast to the cutting of other species of gemstones, each facet is placed and polished in one step.

 
Inspection by the Brillianteerer
Careful attention to detail is necessary to be certain that each facet is in its correct position and that the best polishing directions are adhered to. The brillianteerer constantly picks up the stone to judge its progress, as each facet goes on quickly at this stage.

 
Pavilion Completed
The final step in the fashioning is the placing and polishing of the eight pairs of lower-girdle facets, completing the 58 total facets.

The fashioned diamond will now be cleaned by boiling in acid, and lastly inspected for perfection.

 
The Round Brilliant
It is now a product of artisans, ready to grace a coveted piece of jewelry. As light plays off this jewel, its beauty released, we can all appreciate this long process of true craftsmanship.