Diamond cutting is not a complex process from technological point of view but it's difficult and hard human job. The main operations are stayed the same during several hundreds years and are carried out by hand. Although they are constantly improved in order to increase the producivity of diamond cutting and to improve the quality of made diamonds and also for creation of new forms and types of cutting.
In diamonds cutting it's necessary to use special knowledge, to have patience, assiduous and don't be hurry in decision concerning that or this future brilliant. The decision of how to cut the diamond is taken according to its natural form, internal crystalline structure of gemstone, inclusions and defects. The diamond can have rather complex internal structure and the cutter should chose between the maximal possible size and maximal high quality of the brilliant. Dy any way the brilliant should be of ideal form.
Technology of diamond cutting includes several consecutive technical operations: fore-industrial research of diamond crystals, their marking-out, cleaving or sawing, bruting, abrasion, polishing, washing and valuation.
The main technological principle is that the diamond is cut only by diamond though different laser equipment which carries out some operations more effectively is introduced in this process.
Fore-industrial analysis is carried out in order to determine the technological direction in diamond cutting. Here the grading according to the form of diamonds is carried out, also determine the diamonds for sawing (single or repeated one), for cleaving and bruting. The features of every crystal are determined, strained and defective crystals are revealed, also the character and location of defects are determined. As a matter of fact on the stage of fore-industrial analysis the prognosis of weight of the ready brilliant, the basic geometric parameters, value features and the cost are carried out.
Today modern technologies in analysis, optimization and planning of diamond cutting are used in cutting mills of new generation. Technologist (cutter) can value the ability of the diamond and plan its cutting with the help of computer systems of modeling of diamond cutting. The system makes the immediate analysis of raw diamond and shows how to get an ideal brilliant from it. Then after choose of the cutting way it's possible to assign parameters for laser marking-out. The size of brilliant is very important factor of value and cost of the ready gemstone because of this the loss of the weight in every stage of cutting and polyshing is carefully seen by technologist (cutter) who controls the whole process of cutting.
During the process of marking-out lines are put on the crystal which form the plane of sawing and cleaving, in the case of bruting – the plane of the diamond ground is put. The main aim of marking-out is to get the brilliant or combination of brilliants of maximal cost.
During the process of cleaving or sawing the diamond is divided into parts which are made for optimal use of the diamond stuff. During this process often natural defects of the diamond are taken away that increases the price of the future brilliants. The technological process is rather complex and difficult and consists of several operations carried out in consecutive order. This operations requires attention and exceptional accuracy. The further work with received half-finished product and the result depend on how these operations will be carried out.
Bruting is the process of taking down the superfluous mass of crystal. This operation is carried out in cutting of crystals with anomalous form and of crystals fragments when it's not expedient to saw or to cleave them. As a result of bruting we get the half-finished product which is fit for using in operations of preliminary putting facets and for abrasion. Usually bruting is carried out just after the fore-industrial analysis but it also can be fulfilled after cleaving or sawing of complex in shape diamonds.
Abrasion of diamonds is considered to be the most responsible process in the whole circle of producing diamonds. Coefficient of use of the diamond's stuff considerably depends from this stage. The basic shape of the future diamond is created during abrasion. Abrasion can be carried in one stage or in several steps when it is divided into draft and pure ones.
The quality of cutting is one of the important parameters in diamond valuation. Diamond cutting is the process of putting facets by a determined angle to each other. This fact allows diamond maximally refracts rays of light. Facet is got by rubbing of grinding wheel (diamond disk). Linseed-oil is used as a grinding agent. First the large even facet is taken away on the top of the gemstone – ground. Then the main facets are put from below and this cone-shaped part is called pavilion. Then facets are whetted on the top – crown. Then additional facets are put on the pavilion and then again – on the crown. Every facet requires the observance of exact sizes, shape and angle. Diamond is also outlined with faceted girdle and caletta (pin) parallel to the ground appears below in the lowest part of pavilion. The cutting itself is putting of facets and wedges on the cut half-finished ground in the determined sequence with observance of the main parameters of cutting.
Processes of cutting and polyshing are combined and carried out on the same grinding wheel which parts are processed with diamond powder of different size. Polyshing provides the high purity of the diamond surface and as a result high coefficient of refraction of light from its surface. Processes of cutting and polyshing are the most responsible and difficult.
Washing of brilliants is the final stage in the industrial cycle of diamond producing. The aim of washing is to take away industrial dirt and oil from the diamond's surface. Washing consists of several sequence operations. For this purpose washing solution on the basis of concentrated sulfuric acid with addition of determined quantity of potassium nitrate, distillate water and pure alcohol. After this brilliants become pure and get their trade view.