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The different steps to turn a rough diamond into a cut diamond- The work of the diamond cutter and trader

The Lapidaire

The word « lapidaire » which comes from the Latin word Lapis, is used in French for both the technique and the trade of cutting and shaping stones, precious or non-precious to create jewellery or art. The « lapidaire » is not involved in the actual cutting of diamonds, this work is only executed by the « diamantaire », the density of diamonds requires a specific cutting method.

In both cases, the « lapidaire » and the « diamantaire » must turn a rough stone into the most beautiful stone, meaning the biggest and purest stone, with the most profound and uniform color, and keep the amount of stone that is lost in the process to a minimum. The lapidaire is also a trador and merchant and often gemmologist ( gemmology is the science that studies precious, semi-precious and decorative stones). In this profession it is necessary to have great knowledge of the material that is traded in order to be successful.

There are different techniques for cutting coloured stones, depending on the nature of the stones an the result the cutter wants to obtain. In general :
- First the stones are cut with the use of a small circular saw.
- Secondly they are reduced to a basic shape with small grinding stones that consist of discs set with diamonds.
After this, small cracks and blemishes are taken of with a very fine polish. Facetting the stone is the most complex step in the process and requires a lot of experience : the stone is polished with the help of a device that consists of a rotating or vibrating disc.
The final polishing (turning polish or with the help of vibrations) is done in order of taking of the sharp edges and to give the stone a finishing touch using diamond powder.

The Diamantaire

The first step of cutting a diamond is to examine the stone with great care. During this examination the diamantaire draws a plan for splitting the diamond and decides on the direction of the cut based upon the christalisation axis. Lines are drawn on the stone with ink to serve as guidelines for the following steps. The stone is then fixed in a wooden support which is also secured firmly in a vice.
The diamantaire must choose the best cut for the rough diamond, based on the weight, clarity and color. Sometimes this is a difficult decision, because a diamond that is graded as excellent or very well cut can become more valuable than a diamond of more weight but less quality of cut.
During the cutting process a diamond looses 50-60% of it’s initial weight.
To create a beautiful diamond, a certain number of steps must be taken.

- Observation :

The first step of cutting a diamond is to examine the stone with great care. During this examination the diamantaire draws a plan for splitting the diamond and decides on the direction of the cut based upon the christalisation axis. Lines are drawn on the stone with ink to serve as guidelines for the following steps. The stone is then fixed in a wooden support which is also secured firmly in a vice.

The splitting or sawing :
Nothing is harder than a diamond. That is why it can break to pieces ! It’s crystals actually contain splitting lines along which the chemical compounds are less strong than in other directions. With a well directed hit the stone can be split along these lines. Splitting lines are always oriented parallel to a crystal plane. The diamond splits parallel to four principal sides of the octaedre.
The diamond is split along the chosen line, by hammering in a very thin steel blade with a short hit. The stone devides itself in two, leaving to perfectly flat surfaces, equal to a polished facette. The work of the splitter is one of the most difficult, because it brings a lot of responsability.
Nowadays diamonds are more often sawn than split. The saw that is used consist of a metal disc of which the edge is covered with diamond powder and oil.
Nowadays there are certain systems that use circular saws or laser:

The laser can make certain cuts that are impossible to perform with a saw. On the other side, the cuts are less clean because the technique leaves small marks on the surface. Sawing is less delicate than splitting, because it gives a bit more room in handling the stone. One can in fact change a few degrees in direction to eliminate a inclosure or the enhance the shape of the stone. The stone must be marked beforehand to determine the cutting plan. Then the stone is firmly secured to ensure a fixed position while sawing. The sawing must result in getting the biggest possible table and strongest possible culasse.

- Undoing the stone of roughness:
It helps to round the diamond before shaping the facets. The stone is somewhat prepared in size and it’s shape is roughly determined by the machine. The stone is fixed to a device which rotates around 1700 rpm and which forces it against two diamond tips. The final form of the stone is formed.

- The facetting and polishing :
This is an essential step which determines the symmetry, proportion and the degree of finishing (or polish). This largely determines the value of the diamond.
The diamonds are most often cut and shaped in 57/58 facets. These are made on a flat horizontal disc, covered with a mixture of diamond powder and oil. The stone, held by pincers, is forced against the surface of the disc just long enough to form the facet. The cut must be executed with extreme regularity in a pre-determinated angle. Today a part of the cutting is done in an automated process. Following the preset data in teh machine, the pincers turn automatically to the right angle in order to create the next facet. The computer gives the opportunity to closely watch and visualize the steps from a rough diamond to a cut stone. In order to do this, it has to receive all the information concerning the rough stone in order to create the desired final product one wishes to obtain.