Where diamond cutting all started
After all is said and done, diamond cutting is what makes the difference between the uncut diamond in the rough and the final polished sparkling gemstone.
The raw diamond appears like a lump of molten glass that is coated with a translucent film.
Uncovering its great beauty depends on man’s skill to take maximum advantage of the physical laws of optics.
It has taken a long time to learn how to cut a diamond so as to maximize its brilliance.
By the mid-1700s, the science of optics and the understanding of cutting diamond converged.
The result was the development of the brilliant round cut….the most popular diamond cut to this day.
The brilliant cut diamond represents the highest advances made in the art of diamond cutting.
It brings out the most brilliance and fire from the diamond’s natural properties.
There has continued to be some debate in diamond cutting cirlces on how to simultaneously maximize brilliance, sparkle and fire in a diamond…also know as the “ideal cut”.
Enter a mathematical approach
In 1919, master gem cutter and mathematician Marcel Tolkowsky calculated a compromise.
A perfectly symmetrical diamond cut with 58 facets and precise proportions.
The most widely accepted proportions for diamonds cut today have evolved from Tolkowsky’s model.
The transformation of a rough diamond to a cut one is simply amazing.
There are a few basic steps that are required in order to transform a piece of rough diamond into a cut & polished one.
These steps require a tremendous amount of skill and patience on the part of the diamond cutter…who has to make many calculations & decisions before the work begins.
The initial step is to choose the shape and size of the final diamond which will be created from a particular piece of diamond rough.
This is a very complicated decision, since it involve trade offs to avoid inclusions & cracks.
This will make the diamond smaller but less included and possibly more valuable.
The only exception is for Internally flawless diamonds as they contain no inclusions.
Once that is decided, the cutter marks on the stone with ink what part of the stone shall be removed by cleaving or sawing, in order to get it in proper shape for further work.
Diamonds can be cleaved or sawn.
The expert must decide which option to choose.
This will depend on whether the diamond has deep cracks or not.
Cleaving a cracked diamond can cause it to shatter as its structure has already been compromised.
Cleaving the diamond only takes a few seconds.
It involves a chisel and hammer and it must be done with the grain of the diamond otherwise the stone will fracture & be damaged.
Most diamonds are sawn.
The sawing process involves a special blade coated with diamond dust which spins at high speed to gradually cut through the stone.
This is an important diamond cutting step as it determines how big or small the final diamond will be.
There is also a relatively new laser technology that is used to saw rough diamonds.
Since diamond is the hardest of all natural minerals, one diamond is fixed on a small lathe.
The other is fixed on a stick and held in the operators hand.
This is the only way to actually form the shape of the diamond; by having it worked on by a second diamond.
The shape obtained corresponds to the double cone of the brilliant cut.
To obtain other shapes, the diamonds are ground on a rotating disk that is covered with diamond dust.
Polishing is the very last step of the diamond cutting process & requires much experience.
The diamond held in a dop (a specially designed rig) is polished on a 12 inch wide horizontally rotating wheel spinning at 2000 – 3000 rpm….coated with diamond powder and oil.
Initially, the diamond cutter carves 18 facets into the diamond….upon which all of the other facets will be built.
This is a very crucial stage since it will have a huge impact on the final cut quality of the diamond.
The corners of all facets & placement of angles are judged by eye without elaborate instruments….only a loupe is used to gauge the cut.