Method of cleaning large crystals of natural diamonds |
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IPC classes for russian patent Method of cleaning large crystals of natural diamonds (RU 2447203):
 
Method for diamonds purification / 2367601
Method includes stagewise diamonds treatment in autoclave at increased temperature and pressure under the action of microwave radiation: in the first stage -with mixture of nitric acid and hydrogen peroxide, in the second stage- with mixture of concentrated nitric, chlorhydric and hydrofluoric acids. The treatment in both stages is carried out in acids gas phase at autoclave filling 45-55%, in the first stage the volume ratio nitric acid/hydrogen peroxide is 4:1 respectively, the treatment is carried out at temperature 215-250°C during 15-60 min. In the second stage the volume ratio nitric acid/chlorhydric acid/hydrofluoric acid is 5:4:1 respectively; the treatment is carried out at the same temperature during 15-150 min. In the third stage the mixture is treated with 5% solution of chlorhydric acid/ during 5-15 min and temperature not more than 160°C.
 Mono-crystal diamond produced by chemical deposition method from gas phase and method of production of such diamond / 2288302
Diamond is produced from gas phase by chemical deposition on diamond substrate whose surface is practically free from any defects in crystal lattice in flow of carrier gas in atmosphere containing nitrogen at concentration lesser than 300 part/109. Diamond thus produced is chemically pure with no defects in crystal lattice at enhanced electronic characteristics as compared with purest natural diamonds.
 Monocrystal diamond layer of high thickness, method of production of such layer and precious stones made from this layer / 2287028
Diamond layer at thickness more than 2 mm is obtained through chemical deposition from gaseous phase. Method includes homo-epitaxial growth of diamond layer on surface of backing at low level of defects in atmosphere containing nitrogen at concentration lesser than 300 billion parts of nitrogen.
 A method of manufacturing a diffractive optical elements on diamond and diamond-like substrates / 2197006
The invention relates to the optical instrument and is intended to create complex diffractive optical elements (DOE) - kinoforms, pokushalov, proofreaders and t
 Procedure for production of diamonds of fantasy yellow and black colour / 2434977
Procedure consists in ion-energy-beam processing diamonds with high power ion beam of inert chemical element of helium with dose of radiation within range from 0.2×1016 to 2.0×1017 ion/cm2 eliminating successive thermal annealing.
 Procedure for radiation of minerals / 2431003
Procedure for radiation of minerals in neutron flow of reactor in container consists in screening radiated minerals from heat and resonance neutrons. Composition of material and density of the screen is calculated so, that specific activity of radiated minerals upon completion of radiation and conditioning does not exceed 10 Bq/g. Before radiation contents of natural impurities in radiated minerals can be analysed by the method of neutron activation analysis. Only elements activated with resonance neutrons are chosen from natural impurities of radiated minerals. Tantalum and manganese or scandium and/or iron or chromium are used as elements of the screen. Chromium-nickel steel alloyed with materials chosen from a row tantalum, manganese and scandium are used in material of the screen.
 Device for irradiating minerals / 2406170
Device for irradiating minerals has a reactor active zone, an irradiation channel, a container and extra slow neutron filter. Inside the container there are slow and resonance neutron filters. The extra slow neutron filter surrounds the container and is fitted in the irradiation zone. A gamma-quanta absorber of the reactor is placed between the container and the active zone of the reactor. A resonance neutron absorber is added to the extra slow neutron filter. The thickness of these absorbers enables to keep temperature inside the container not higher than 200°C during irradiation.
Polarisation method of monocrystal of lithium tantalate / 2382837
Invention relates to industrial production of monocrystals, received from melt by Czochralski method, and can be used during polarisation of ferroelectrics with high temperature Curie, principally lithium tantalate. On monocrystal of lithium tantalate by means of grinding it is formed contact pad, surface of which is perpendicular to optical axis of crystal or at acute angle to it. Monocrystal is located between bottom segmental or laminar platinum electrode and implemented from wire of diametre 0.3-0.6 mm top circular platinum electrode through adjoining to its surfaces interlayers. In the capacity of material of interlayer it is used fine-dispersed (40-100 mcm) powder of crystalline solid solution LiNb1-xTaxO3, where 0.1≤x≤0.8, with bonding alcoholic addition in the form of 94-96% ethyl alcohol at mass ratio of alcohol and powder 1:2.5-3.5. Monocrystal is installed into annealing furnace, it is heated at a rate not more than 70°C/h up to temperature for 20-80°C higher than temperature Curie of monocrystal and through it is passed current by means of feeding on electrodes of polarising voltage. Then monocrystal is cooled in the mode current stabilisation at increasing of voltage rate 1.2-1.5 times up to temperature up to 90-110°C lower than temperature Curie, and following cooling is implemented in the mode of stabilisation of polarising voltage at reduction of current value through monocrystal. At reduction of current value 3.0-4.5 times of its stable value voltage feeding is stopped, after what monocrystal is cooled at a rate of natural cooling-down. Monocrystal cooling up to stop of feeding of polarising voltage is implemented at a rate 15-30°C/h.
 Method of producing mono-crystalline plates of arsenide-indium / 2344211
Invention refers to semi-conductor technology of AIIIBV type compositions. The method is implemented by means of bombarding mono-crystalline plates of arsenide-indium with fast neutrons with following heating, annealing and cooling. The mono-crystalline plates are subject to bombardment with various degree of compensation at density of flow not more, than 1012 cm-2 c-1 till fluence F=(0.5÷5.0)·1015 cm-2 , while annealing is carried out at 850÷900°C during 20 minutes at the rate of heating and cooling 10 deg/min and 5 deg/min correspondingly.
 Method of obtaining minerals and device for its realisation / 2341596
Method of obtaining minerals is realised in neutron reactor flow, minerals being placed in layers between layers of substance or mixture of substances, containing elements, absorbing thermal and resonance neutrons, layers being separated with aluminium interlayer and surrounded with filtering unit from substance or mixture of substances, containing elements, absorbing thermal and resonance neutrons, with cadmium screen, layer thickness and geometrical parameters of unit are calculated in such way that at the moment of exposure to radiation mineral temperature does not exceed 200°C, and "Фб.н./Фт.н." ≥10, where "Фб.н." is density of flow of fast neutrons with energy higher than 1MeV, "Фт.н." - density of thermal neutrons flow. Described is device for mineral irradiation, containing hermetical filtering unit, filled with substance or mixture of substances, containing elements, absorbing thermal and resonance neutrons, with axial hole, in which cadmium screen is placed and also placed is a case open from the bottom for partial filling with heat carrier, operation volume of case is filled with minerals, placed in layers between layers of substance or mixture of substances, containing elements, absorbing thermal and resonance neutrons, layers being separated with aluminium interlayer.
 Diamond working method / 2293148
Method comprises steps of acting upon crystal with electron beam whose integral flux is in range 5 x 1015 - 5 x 1018 electron/cm2; annealing crystal in temperature range 300 - 1900°C and acting with electron beam in condition of electric field having intensity more than 10 V/cm at least upon one local zone of crystal for imparting desired color tone to said zone. Local action of electron beams is realized through protection mask. As irradiation acts in condition of electric field local flaws such as bubbles or micro-inclusions are effectively broken.
Method of cleaning diamond / 2285070
Proposed method includes stage-by-stage treatment of diamond by mixture of acids under action of microwave radiation; at first stage, use is made of nitric acid and hydrogen peroxide at volume ratio of components of 10:1, respectively; at second stage, volume ratio of mixture of concentrated nitric acid, hydrochloric acid and hydrofluoric acid is 6:2:1, respectively; diamond is treated at temperature not higher than 210°C, pressure of 35 atm as set by loading ratio of autoclave equal to 1:10 at power of oven of microwave radiation of 1200 W; duration of each phase does not exceed 40 min. Proposed method ensures perfect cleaning of diamonds from contamination of mineral and organic nature including bitumen compounds on surface and in cracks of diamond.
Method for treating colored diamonds and brilliants for decolorizing them and releasing stresses / 2281350
Method is realized due to physically acting in closed reaction space upon samples of diamonds and brilliants by means of high pressure and temperature for time period sufficient for enhancing their quality. Pressure acting upon samples is in range 6 - 9 GPa in region of thermodynamic stability. Temperature during physical action upon samples is in range 1700 - 2300°C. Samples are subjected to physical action in medium of graphite powder filling reaction space. Heating till high temperature is realized due to applying AC to samples of diamond or brilliant through graphite powder at specific electric current power from 0.18 kWt/cm3 and more. Then electric power is gradually increased from zero till working value and further it is decreased and increased at least two times for some time interval at each change of electric power. Process of annealing samples is completed by smoothly lowering electric current power till zero. At physical action upon sample electric current intensity is lowered by 11 - 13 % and it is increased by 15 - 17 % for time interval from 8 min and more at each change of electric power. Sample is AC heated and it is cooled at rate no more than 0.05kWt/min per cubic centimeter of reaction volume of chamber.
 Method of shaping high-melting and chemically stable materials / 2252280
Method comprises etching the surface of articles made of high-melting chemically stable materials by applying the layer of an agent interacting the article material and heating the surface by laser pulse irradiating. The surface of the article is simultaneously affected by the laser pulses and vapors of a volatile composition, which is subjected to the pyrolytic decomposition to produce the above mentioned material. The amplitude of the laser pulse should be sufficient to cause the evaporation of the material.
Procedure for production of diamonds of fantasy yellow and black colour / 2434977
Procedure consists in ion-energy-beam processing diamonds with high power ion beam of inert chemical element of helium with dose of radiation within range from 0.2×1016 to 2.0×1017 ion/cm2 eliminating successive thermal annealing.
 Procedure for surface of diamond grains roughing / 2429195
Procedure for surface of diamond grains roughing consists in mixing diamond grains with metal powder and in heating obtained mixture to temperature of 800-1100°C in vacuum as high, as 10-2-10-4 mm. As metal powders there are taken powders of iron, nickel, cobalt, manganese, chromium, their alloys or mixtures. Powders not inter-reacting with diamond grains at heating can be added to the mixture.
 Colourless diamond layer / 2415204
Method involves preparation of a substrate, using a HOPF-synthesis atmosphere which contains nitrogen in concentration of over 300 parts per billion (ppb), and adding to the synthesis atmosphere a second gas which contains silicon atoms as dopant atoms of a second type, where dopant atoms of the second type are added in a controlled manner in an amount which ensures reduction of negative effect of nitrogen on colour, where the layer of monocrystalline diamond has thickness of greater than 0.1 mm, concentration of silicon in the dominant volume of the diamond layer is less than or equal to 2·1018 atoms/cm3, concentration of nitrogen in the dominant volume of the diamond layer is greater than 2·1016 atoms/cm3 and less than or equal to 2·1017 atoms/cm3, and the ratio of concentration of nitrogen to concentration of silicon in the dominant volume of the diamond layer is between 1:20 and 20:1. Addition of a source gas which contains silicon counters the negative effect of nitrogen contained in the HOPF-synthesis atmosphere on the colour of the diamond.
Method of depositing diamond phase nucleation centres onto substrate / 2403327
Method involves preparation of a suspension with weight concentration of nanodiamond particles in a water-based solution selected from the relationship: K=α(ρa/ρb)(r/R)3, feeding the suspension into a gas stream having spraying nozzle velocity from 100 m/s to 400 m/s in order to spray the suspension of nanodiamond particles and deposit them onto a substrate placed at a distance from the sprayer equal to 1-2 times its diametre for a period of time defined the relationship: t=(Sr)/(β(ρb/ρa)KQ), where: K is the weight concentration of nanodiamond particles in the suspension, wt %; a is a coefficient 1≤α≤10; ρa is density of nanodiamond particles, ρa=3.2 g/cm3; ρw is density of water, ρw=1 g/cm3; r is average radius of the nanodiamond particles, r=(4-15) nm; R is average radius of the sprayed droplets, R=(0.5-10) mcm; t is time for depositing the particles, min; β is a coefficient of proportionality, 0.05≤β≤0.1; S is surface area of the substrate, cm2; Q is flow rate of the suspension, Q=(0.06-6.0) cm3/min.
 Colourless monocrystalline diamond obtained via high-growth rate chemical gas-phase deposition / 2398922
Method involves controlling temperature of a diamond growth surface so that all temperature gradients on the said surface do not exceed 20 єC, and growth of a monocrystalline diamond on the said surface through chemical gas-phase deposition in a microwave plasma at growth temperature in a deposition chamber, the atmosphere of which contains approximately 8-20% CH4 per unit H2 and approximately 5-25% O2 per unit CH4. Diamonds larger than 10 carat may be obtained using the method, which is the subject of the present invention.
Procedure for production of nano-diamonds / 2396377
Invention refers to process of production of nano-diamonds of great industrial importance in electronics as high temperature semi-conductors, high-sensitive metres in complex metering instruments with powerful solid-state laser, etc. Nano-diamonds are produced by crystallisation from water solution of spirit (ethyl or methyl). Also to stabilise nano-diamonds formation spirit is mixed with amino-acids. At least one alkali metal (lithium or potassium) is added into the produced mixture to bond free atoms of hydrogen escaping in the process of spirit decomposition. The crystallisation process is carried out in a closed chamber at temperature 400-700°C during 4-120 hours.
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FIELD: chemistry. SUBSTANCE: method involves step-by-step treatment of diamonds in an autoclave at high temperature and pressure, including a step for cleaning with a mixture of nitric acid and hydrogen peroxide and a step for cleaning with a mixture of concentrated nitric, hydrochloric and hydrofluoric acids under the effect of microwave radiation. After the step for cleaning with nitric acid and hydrogen peroxide, the diamonds are treated under the effect of microwave radiation with hydrochloric acid in gaseous phase at temperature 215-280°C for 15-300 minutes. Further, the diamonds are treated with distilled water at temperature 160-280°C for 5-30 minutes in an autoclave in liquid phase. At the step for cleaning with a mixture of nitric acid and hydrogen peroxide, treatment is carried out with the following volume ratio of components: nitric acid and hydrogen peroxide 4-10:1-3, respectively, at temperature 215-280°C for 15-540 minutes in liquid phase in a system with external heating or in a gaseous phase under the effect of microwave radiation. At the step for cleaning with a mixture of concentrated nitric, hydrochloric and hydrofluoric acids, treatment under the effect of microwave radiation is carried out with the following volume ratio of components: nitric, hydrochloric and hydrofluoric acid 1-6:1-6:1-3, respectively, in gaseous phase at temperature 215-280°C for 15-300 minutes. EFFECT: invention increases the effectiveness of the process of cleaning diamonds larger than 4,0 mm with high efficiency of the equipment used. 3 cl, 3 dwg, 2 tbl, 1 ex
The invention can be used for high-quality purification of natural diamond crystals larger than 4.0 mm from the surface contamination and remove foreign impurities. A known way to clean diamond (A.S. NO. 1104791, SW 31/06, publ. 20.12.2000, bull.№35), including the diamond, when heated with a mixture of nitric and hydrochloric acids at an elevated pressure in the reaction vessel made of fluoropolymer, and the mixture is further added hydrofluoric acid at a volume ratio of concentrated nitric, hydrochloric and hydrofluoric acid 3:1:(1-2), respectively, at 220-250°C for 1.5-3 hours. This method allows you to clear the diamonds only from contaminants contained on the surface of the crystals and the resultant enrichment of diamond ore, which are presented in the form of traces of metals, inorganic compounds and oils. The disadvantage of this method is that it does not provide high-quality cleaning of mixed origin, which appeared during the growth of diamond or later as a result of various secondary processes, because the redox potential of the reaction mixture used is insufficient for the oxidation of the bitumen. Also known way to clean diamond (H-ka of the Russian Federation No. 2004132810, SW 9/00, publ. 27.04.06, bull. No. 12), including processing in autoclavable elevated temperature and pressure with a mixture of acid - hydrochloric, nitric and hydrofluoric, and processing the mixture of acids are Paladino under the influence of microwave radiation at the first stage, a mixture of nitric acid and hydrogen peroxide at a volume mixing ratio 10:1, respectively, and in the second phase volume ratio mixture of concentrated nitric, hydrochloric and hydrofluoric acids is 6:2:1 respectively, the duration of each stage is not more than 40 minutes. When implementing this method is quite effective cleaning of diamonds from bitumen contamination. However, only 57% of those in need of cleaning diamonds cleared completely, 31% partially. In 12% of the crystals in the complete destruction of bitumen contamination in their place appear transparent red-brown spots (dirt in the cracks), shifting the color of the crystals in the region of the brown color, which reduces the price of diamonds. In addition, the disadvantage of this method is that the number of crystals of the dirt red color (in particular, iron oxides) in the treatment away from the crack is located on the surface of diamond crystals, which required additional input stage of purification. All this makes the known method is not effective enough. The closest to the essence of the technical solution is the method of purification of ALM is call (U.S. Pat. Of the Russian Federation No. 2367601 dated 25.12.2007, SW 33/04, SW 33/12, SW 29/04, SW 31/06, publ. 20.09.2009), including sequential processing of diamonds in an autoclave at elevated temperature and pressure under the influence of microwave radiation. In the first stage processing is done within 15-60 min with a mixture of nitric acid and hydrogen peroxide at a volumetric ratio of 4:1, respectively. In the second stage processing is done within 15-150 min with a mixture of concentrated nitric, hydrochloric and ftoristovodorodnoi acid at a volumetric ratio of 5:4:1, respectively. The peculiarity of the method is that the processing on the first and second stages are in the gas phase acids during filling of the autoclave 45-55%. In this case, the temperature of the first and second stage processing support equal 215-250°C. In the third stage, the diamond is treated with a weak (5%) solution of hydrochloric acid at a temperature not exceeding 160°C for 5-15 minutes The application of this technology allows high efficiency clear crystals up to a maximum of 8.0 mm, but not good enough cleans larger crystals due to incomplete removal of contamination bitumen located in the cracks, going deep inside the crystal. Large crystals of natural diamond have a big and deep cracks that require more time and higher temperature processing. The dependence of EF is aktivnosti diamond cleaning, treated this way, their size can be seen when comparing the results given in table 1. The difference between the average values of this indicator for classes to-4.0+2.0 mm and -8,0+4.0 mm is at 8.36%, and between classes to-4.0+2.0 mm and -20,0+8.0 mm 15,23%. Comparison of the values shows a significant increase efficiency deep cleaning of large crystals.
The technical result of the invention is to improve the quality of cleaning of large crystals of natural diamond (>4.0 mm). This technical result is achieved in that in the method of purification of large crystals of natural diamond, comprising the sequential processing of diamonds in an autoclave at elevated temperature and pressure, including the stage of cleaning with a mixture of nitric acid and hydrogen peroxide and the stage of cleaning with a mixture of concentrated nitric hydrochloric and hydrofluoric acids under the influence of microwave radiation, way after the stage of purification of a mixture of nitric acid and hydrogen peroxide includes an additional stage in which the processing under the influence of microwave radiation are hydrochloric acid in the gas phase at a temperature 215-280°C for 15 to 300 minutes, and after cleaning diamonds treated with distilled water at a temperature of 160-280°C for 5-30 min in an autoclave in the liquid phase. At the stage of purification of a mixture of nitric acid and hydrogen peroxide treatment is carried out at a volume ratio of components (nitric acid and hydrogen peroxide) (4-10):(1-3), respectively, at a temperature 215-280°C for 15-540 min in liquid phase in the system with external heating or in the gas phase under the influence of microwave radiation. The cleanup phase and a mixture of concentrated nitric, hydrochloric and hydrofluoric acid processing 4 is carried out at a volume ratio of components (nitric, hydrochloric and hydrofluoric acids) (1-6):(1-6):(1-3), respectively, in the gas phase at a temperature 215-280°C for 15 to 300 minutes This method allows you to effectively clean large crystals of natural diamond due to sequential sequential implementation of multiple target processing stages, each of which removes only a certain type impurities, combining the design of autoclaves and ways of heating, including the use of autocl the different installations with external heating, it allows to increase the duration of processing of diamonds at higher temperatures (in contrast to existing systems with microwave radiation). The upper temperature limit due to the possibility of the equipment being used. The lower limit is due to the composition of impurities. It should be noted that the temperature depends on the velocity of the flowing reaction and accordingly the speed of treatment. Thus, by increasing the temperature decreases the processing time while maintaining the efficiency of cleaning of diamonds. The method is as follows. The diamond lead in four stages, which may be divided offunctional as follows: 1. cleaning stage of diamond crystals from bitumen and technological fats (stage cleaning with a mixture of nitric acid and hydrogen peroxide); 2. cleaning stage of diamond crystals from metal oxides (stage cleaning with hydrochloric acid); 3. cleaning stage of diamond crystals from the mineral impurities and degradation products formed during the previous processing stages (stage cleaning with a mixture of concentrated nitric, hydrochloric and hydrofluoric acids); 4. stage washing of the crystals of diamond and reagents (processing stage of distilled water). In the first stage of the purification is carried out at the same time is the temperature value from 215 to 280°C and time consuming process from 15 to 540 minutes at a given temperature. The duration of the process is determined by the magnitude of contamination, the depth of its location in the diamond, the crystal grain size and the content of crystals with impurities in the treated batch of diamonds. A further increase in processing time at this stage is inappropriate in connection with the complete purification of the crystals from the bitumen up to 3.5 cm or weighing less than 140 carats within the prescribed limits of time. The treatment is carried out with a mixture of nitric acid and hydrogen peroxide at a volume ratio (4-10):(1-3), respectively. Cleaning of the diamond crystals are produced either in the liquid phase (filled diamonds reagent entirely) in the case of systems with external heating or in the gas phase under the influence of microwave radiation. Selecting one of the modes is determined by the hardware. The second additional stage processing of natural diamonds crystals are in hydrochloric acid. The temperature of the second stage processing support equal 215-280°C. the treatment is carried out in a gaseous environment in systems with microwave heating for 15 to 300 minutes This step is necessary for the removal of metal oxides, causing a colour change of diamond crystals (mainly iron). In the third stage, the treatment is carried out with a mixture of concentrated nitric, hydrochloric and hydrofluoric acids when the volume of the nom ratio of components (1-6):(1-6):(1-3), respectively. The temperature of the third stage of processing support equal 215-280°C. the treatment is carried out in a gaseous environment in systems with microwave heating for 15 to 300 minutes Variations in the compositions of reagents, temperature and processing time due to the size of the processed crystals, the characteristics of the material composition of diamonds and dirt impurities in the treated mass of crystals obtained from different fields. In the final fourth stage leaching diamonds from reagent)to effectively clean the diamond crystals from the acid residue in the cracks, diamond processing is carried out in autoclaves at a temperature of from 160 to 280°C in distilled water. Adding in distilled water acid is not required in connection with the presence of diamonds remainder of the reagent from the previous phases. Washing of the crystals produced in the liquid phase (diamonds filled with distilled water completely within 5 to 30 minutes. The variation of the temperature and time of this treatment (washing of the crystals of diamond and reagents) is determined by the type of used autoclaves. The use of this method allows for highly efficient cleaning of the maximum number of impurities of large crystals of natural diamond (larger than 4.0 mm) thus greatly increasing their Ryno is a relative value. The set of features of this technical solution is not identified from the patent documents and scientific and technical information that is indicative of inventive step of the claimed technical solution. An example of a specific implementation For full disclosure of technical nature and advantages of the present invention shows an example where the source data for the implementation of the proposed method adopted in the following. Purification was subjected to party diamond particle size of 8.0 mm single field, it was treated as a problem of diamond crystals (having cracks with dirt), and the diamond crystals without visible dirt. Used to process the system "DAB-3" and "Speedwave MWS-3+" firm "Berghof". Install "DAB-3 is a system with external heating, the metal shell PTFE TFM autoclave with a capacity of 450 ml of withstanding pressure up to 200 bar. Autoclave this installation can withstand temperatures up to 280°C for a long time, and its capacity allows you to handle up to 4000 carat per load. Install "Speedwave MWS-3+is the autoclave system with microwave heating, equipped with 8 autoclaves DAK-100 PTFE TFM capacity of 100 ml each with a maximum temperature of 250°C, can withstand the extreme pressure of 100 bar, and allowing the amount to be treated is up to 5000 carats of diamonds. As an example, in table 2 the results of processing 3 parties diamond particle size of 8.0 mm diamond Processing in the first stage was carried out in the installation "DAB-3" at a temperature of 265°C. the First batch of diamonds was processed within the 3.7 hours, others within 4,25 and 4.0 hours. In the second and third stage of data crystals were processed in the installation "Speedwave MWS-3+" for 1 hour at 220°C. In the final stage (stage leaching) diamonds were processed in the installation "Speedwave MWS-3+" for 15 minutes at 220°C.
Figures 1-3 illustrate the efficacy produced by the purification of large crystals of natural diamond technology, carrying out the proposed method, where: Figure 1 - external view of the crystal mass 13 carats before and after deep thermochemical treatment; Figure 2 - the appearance of the crystal mass 21,7 carats before and after deep thermochemical treatment; Figure 3 - the appearance of the crystal 137,75 carats before and after deep thermochemical treatment. 1. The method of purification of large crystals of natural diamond, comprising the sequential processing of diamonds in an autoclave at elevated temperature and pressure, including the stage of cleaning with a mixture of nitric acid and hydrogen peroxide and the stage of cleaning with a mixture of concentrated nitric, hydrochloric and hydrofluoric acids under the influence of microwave radiation, characterized in that the method after the stage of purification of a mixture of nitrogen to the slots and hydrogen peroxide includes the additional step, which treatment under the influence of microwave radiation are hydrochloric acid in the gas phase at a temperature 215-280°C for 15 to 300 minutes, and after cleaning diamonds treated with distilled water at a temperature of 160-280°C for 5-30 min in an autoclave in the liquid phase. 2. The method according to claim 1, characterized in that the cleanup phase mixture of nitric acid and hydrogen peroxide treatment is carried out at a volume ratio of components (nitric acid and hydrogen peroxide) (4-10):(1-3), respectively, at a temperature 215-280°C for 15-540 min in liquid phase in the system with external heating or in the gas phase under the influence of microwave radiation. 3. The method according to claim 1, characterized in that the cleanup phase and a mixture of concentrated nitric, hydrochloric and hydrofluoric acid treatment under the influence of microwave radiation is carried out at a volume ratio of components (nitric, hydrochloric and hydrofluoric acids) (1-6):(1-6):(1-3), respectively, in the gas phase at a temperature 215-280°C for 15 to 300 minutes
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