MXPA98001580A - Sili carbide gems - Google Patents

Abstract

Synthetic gems are formed that have extraordinary brilliance and hardness from simple large crystals of translucent silicon carbide, of relatively low impurity, of a simple polytype, which are grown in a furnace system by sublimation. The crystals are cut into rough gems that are then formed into cut gems. A wide range of colors and shades is available due to selective impurity of the crystals during cultivation. A colorless gem is produced by cultivating the pure crystal in a system substantially free of undesirable impurity

Description

SILICON CARBIDE GEMS FIELD OF THE INVENTION The invention relates to synthetic gems. More particularly, the invention relates to synthetic gems formed of monocrystalline, translucent silicon carbide.

BACKGROUND OF THE INVENTION Gems in General; There are a limited number of elements and chemical compounds that have the physical characteristics to be useful as gems. The physical characteristics that are generally accepted as the most important are hardness, refractive index and color, although thermal stability, chemical stability and stiffness are also considered important in many gem applications. To date, the only chemicals technically considered gemstones are diamond (simple crystalline carbon) and corundum (sapphire and ruby [simple crystalline aluminum oxide]) because their hardness, when measured on the Mohs scale, is of about 9 or greater. The Mohs system is a scale for the hardness classification of a mineral with diamond, being the hardness at 10, sapphire at 9, topaz 8, below the softer mineral, the talc, which is 1. The emerald, due that is rare, it is accepted as a precious stone even when its hardness is 7.5, while other gems, such as chrysoberyl, topaz and garnet, are usually classified as semiprecious stones due to their low hardness. Hardness has a practical value, in that it defines the ability of a gem to resist scratching. The refractive index is important because it defines the ability of a gem to reflect light. When materials with a high refractive index are formed in finished gems, they sparkle and look bright when they are. expose to light. The scintillation characteristic of a diamond is mainly due to its high refractive index. The color of a gem is determined by a variety of factors, from the impurity atoms that are available to be incorporated into the crystal lattice to the physical and electronic structure of the crystal itself. A ruby, for example, is simply a sapphire crystal (aluminum oxide) containing a small concentration of chromium impurity atoms. The thermal and chemical stability of a gem can be important during the process of assembling stones in jewelry. In general, this is beneficial if the stones can be heated at elevated temperatures without changing color or reacting with ambient gases (which spoil the surface finish). The rigidity of a gem is related to the ability of gems to absorb energy without breaking, splintering or cracking. A gem must be able to withstand those impact forces normally encountered during a lifetime of use, mounted on a ring or other piece of jewelry. Hardness, refractive index, color, thermal / chemical stability and stiffness are all characteristics that, in combination, determine the usefulness of a material such as a gem. Synthetic Diamond Gems: Dating from the 1960s, an effort to produce synthetic diamonds with gem quality was pursued by the General Electric Company as demonstrated by numerous patents, including US Patent No. 4, 042, '' 6'73 These efforts are centered around the use of very high pressure / high temperature environments for the cultivation of monocristalline diamonds in germ crystals.Crystal-grade synthetic diamonds have generally not gained commercial acceptance. Synthetic Silicon Used as Abrasive and Semiconductor Materials: Silicon carbide is rarely found in nature, however, it has been manufactured for more than eighty years, in crystalline form, for abrasive products. nature and in abrasive products are opaque and non-translucent because they contain substantial levels of impurity atoms. uring the 60s and 70s, significant development activities were initiated with the object of high growth (volume) of silicon carbide crystals of low impurity for use in the production of semiconductor devices. These efforts eventually resulted in the commercial availability of translucent silicon crystals of relatively low impurity in 1990. These silicon carbide crystals are only manufactured and sold as very thin, green or blue plates or "slices" (175 μm - 400 μm) useful for semiconductor devices. Silicon carbide has a very high hardness (8.5 - 9.25 Mohs depending on the politipo [atomic arrangement] and crystallographic direction) and a high refractive index (2.5 - 2.71 depending on the politipo). In addition, silicon carbide is a very rigid material and an extremely stable material that can be heated to more than 1093.33 ° C (2000 ° F), in air, without suffering damage.

Silicon carbide is a complex material system that forms more than 150 different polytypes, each having different physical and electronic properties. The different polytypes can be classified into three basic forms, cubic, rhombohedral and hexagonal. Both of the rhombohedral and hexagonal forms can occur in a number of different atomic arrangements that vary according to the sequence of atomic accumulation.

BRIEF DESCRIPTION OF THE INVENTION The present invention, in a broad aspect, is the discovery that simple, translucent glass silicon carbide, of relatively low impurity - currently used as the material for manufacturing very thin semiconductor devices - can be cultivated with the desired color and then cut, faceted and polished into synthetic finishing gems having (i) an approximate hardness to that of diamond, (ii) excellent rigidity, (iii) excellent thermal / chemical stability, and (iv) a high refractive index that It returns to the gem of silicon carbide as bright, if not brighter, than diamond. In accordance with this aspect of the invention, a simple silicon carbide crystal, preferably of consistent color, is grown by an appropriate technique such as the sublimation technique described in U.S. Patent No. Re. 34,861. Instead of slicing the large crystal into many thin plates, the crystals serve as pear-shaped gemstones that are cut into raw synthetic gems that have a weight in the order of, for example, 1/4 to 5 carats. The raw gems are then formed into finished synthetic silicon carbide gems. The faceting and polishing techniques are derived from those techniques currently used in relation to the faceting and polishing of colored gems, such as rubies and sapphires, which incorporate certain procedures used in relation to diamonds. As mentioned above, preferably single crystals of silicon carbide are cultivated under the same or similar conditions that are used to produce crystals having low levels of impurity, necessary for semiconductor applications, with this being appreciated, of course, that higher impurity levels may be tolerable within the accepted ranges, consistent with the need for materials that have adequate translucency and other optical properties for the use of the gems. Silicon carbide crystals can be grown in a wide range of colors (including green, blue, red, purple, yellow and black) and shades with each color by the appropriate selection of dopants (eg, nitrogen and aluminum) and varying the densities (concentrations) of net doping. The • pure silicon carbide crystals in the hexagonal or ronbohédricas forms are colorless and meet, or exceed, the brilliance of the diamond. The raw silicon carbide gems are cut from simple large crystals and then fabricated into finished gems by a combination of techniques currently employed in relation to conventional colored gems and diamonds. The hardness and rigidity of the silicon carbide allows the stones to be faced with very sharp edges, thus enhancing the appearance and total brilliance of the stones.

BRIEF DESCRIPTION OF THE DRAWINGS Some of the objects have been established, other objects will appear as the description proceeds, when taken in relation to the accompanying drawings, in which: '-' - * '' Figure 1 is a graphic view of a precious stone pyriform comprising a simple large crystal of a polytype of silicon carbide.

Figure 2 is an enlarged graphic view of a rough synthetic gem cut from the single crystal of Figure 1. Figure 3 is an enlarged graphic view of a finished synthetic silicon carbide gem, which is formed from the rough stone of Figure 2 ..

DETAILED DESCRIPTION OF THE INVENTION While the present invention will be described more fully below with reference to the accompanying drawings, in which aspects of the preferred form of practicing the present invention are shown, it is understood at the beginning of the description, which follows, that the persons with skill in the appropriate techniques can modify the invention described herein, as long as the favorable results of this invention are achieved. Accordingly, the description, which follows, is to be understood, being a broad teaching description, addressed to persons with skill in the appropriate techniques, and not as limiting in the present invention. With reference to the drawings, Figure 1 shows a "pear-shaped gemstone" comprising a simple large crystal 11 of silicon carbide weighing approximately 716 carats and from which approximately the raw synthetic gems 105 of five carats (Figure 2) They can be cut. Each of the five-carat rough gems, when formed in a finished gem, will produce a gem of approximate size in the order of two carats. The crystal 11 is substantially cylindrical and approximately 44 mm in height and 40 mm in diameter. In the preferred form of practicing the invention, the crystal 11 is formed of a simple polytype, with a fairly broad energy band space (atoms of net impurity, electrically active, rather low) eg, a hexagonal shape such as SiC 6H, and it has a fairly low net impurity level to make the crystal translucent enough to be used as a gem. The crystal 11 is cultivated by means of an appropriate sublimation or deposition or another culture technique used for the large growth (volume) of simple crystals of silicon carbide, with the preferred method being culture by sublimation in a germ crystal. According to this preferred technique, the crystal 11 is cultivated by introducing a polished monocrystalline seed crystal of silicon carbide of a desired polytype into the furnace of a sublimation system together with silicon and coal containing gas or powder source (fertile material). . The fertile material is heated to a temperature that causes the fertile material to generate a vapor flow that deposits Si, Si2C and SiC2 vaporized to the culture surface of the germ crystal. The reproducible culture of a simple selected polymer in the germ crystal is achieved by maintaining a constant flow of Si, Si2C and SiC2, and by controlling the thermal gradient between the fertile material and the germ crystal. Crystals grown by sublimation techniques have been used as a material from which very thin plates are taken for use in the production of semiconductor devices. These inserts (175 μm - 400 μm) have been green or blue, like glass, with the color (and desired electrical properties), achieved by intentionally doping with selected impurifiers at selected concentrations during the growing process. Pure silicon carbide (intrinsic) has not been commercially cultivated. The extremely low electrical conductivity of pure silicon carbide would give little or no practical value in the manufacture of semiconductor products. However, it has been found that because the hexagonal and rhombohedral polytypes of silicon carbide have wide energy band spaces (> 2.7 electron volts) if there is pure culture (or, equivalently, with a very low level of atoms). of impurity or a level of electrically active impurity atoms) the crystals will be colorless. For pure culture, the simple crystals of colorless silicon carbide, the crystal culture system is kept substantially free of undesirable gases or vaporized impurity atoms which would result in unintentional doping of the crystal as they are grown using low pressure cooking techniques such as they are well known in the art. The preferred polytypes for the colorless silicon carbide gems are SiC 6H and 4H. The germ to start the cultivation of the simple crystal for such gems is the germ that has the same poly, SiC 6H or 4H respectively. To create hexagonal silicon carbide crystals that have different colors, one must intentionally add specific impurity atoms. The cubic or 3C form of silicon carbide, due to its narrower energy band space, will appear yellow when it is purified with impurity atoms. Since a large number of different atomic arrangements of silicon carbide (any of which can be impurified with a number of different dopants in various combinations and concentrations) it is possible to produce gems in a wide range of colors and shades. With the 6H polythype, the commonly used dopants are nitrogen (type n) and aluminum (type p) in concentrations typically in the range of a low range in the order of 10th carrier atoms per cubic centimeter to a high range in the order of 1019 carrier atoms per cubic centimeter. Other impurifiers, such as boron, can be used at sufficient concentrations to achieve the desired colors and shades. The following table gives diverse atomic and doping dispositions that produce several representative basic colors.

Colorless SiC 6H Pure Colorless SiC 4H Pure Blue SiC 6H Al-impure Purple SiC 6H Al-impure elevated Purple SiC 24R N-impure Green SiC 6H N-impure ,. Yellow SiC 3C Pure Yellow-Green SiC 3C N-impure Red SiC 27R N-impure Coffee Light SiC 4H N-impure under Yellow-Orange SiC 8H N-impure Although the above combinations produce a wide variety of colors, all the crystals have two very important characteristics in common, (1) high hardness and (2) high refractive index. The hardness and refractive index of silicon carbide are compared with other gem materials, together with a density comparison: Density Index of Mohs Density Refraction (SG) Emerald 7.5 1.59 2.5 Corundum (sapphire &ruby) 9 1.77 3.9 Diamond 10 2.42 3.5 Silicon Carbide (6H) 9 2.69 3'.2 Silicon Carbide (4H) 9 2.71 3.2 Cubic Zirconia 7.5 1.98 4.7 As illustrated by the above table, silicon carbide, when produced in certain atomic arrangements with the controlled introduction of specific doping atoms, is an excellent color gem material that has physical characteristics that compare favorably with, or exceeding those of corundum and emerald. In its pure hexagonal and rhombohedral forms, (in particular the hexagonal shape which repeats the same atomic structure in all the six layers of atoms, that is, 6H) silicon carbide is the best known candidate to reproduce the characteristics of the diamond .

Formation of the Gems With reference above to the drawings, the crystal 11 of silicon carbide (Figure 1) of perhaps 716 carats is cut into multiple crude synthetic gems 12 (one shown in Figure 2) having a selected weight, by example, five carats. The rough gem 12 preferably has a cubic or approximately cubic shape. To produce a finished gem as illustrated in Figure 3, it has been found desirable to form the raw gem 12 in a finished gem according to a novel process which is best suited to take advantage of the physical characteristics of silicon carbide. . This process incorporates faceting techniques that result in precise angles and very sharp edges to take full advantage of the rigidity and hardness of the silicon carbide material, while incorporating other techniques more similar to those used in colored stones. A more complete description of the formation process will be established after a brief discussion of formation, in general, and certain aspects of the formation of colored gems such as rubies, sapphires and emeralds. Training in General (Previous Technique) The formation of the gem includes four techniques: faceting, polishing, breaking and carving. Faceting produces flat faces (facets) in gems in many different ways. Transparent and highly translucent gems are normally faceted. The less translucent and opaque materials are usually polished, broken or carved due to the optical properties associated with faceting that depend on the reflection of the light inside the stone. One form of the gem is its profile. It looks up, the position in which it means being seen when it is assembled. The other forms that surround it are called fantasy. Some popular forms of fantasy include the well-known emerald cut, cushion-shaped, cushion-shaped, antique, oval, pear-shaped and marquise-shaped. Colored stones (and diamonds over three carats) are usually cut into fancy shapes because a lapidary can hold more weight from the original gem using a fancy shape, thereby improving the weight produced. The standardized, exact facet seen in diamonds is rare in colored stones. One reason is the inability of some colored stones, due to their hardness and rigidity, low, to be faceted at sharp angles without breaking or splintering. Other it is the difference that professionals and consumers of diamonds expect against other stones. The "oriental or native cut" are terms used to describe faceted gems which have distorted shapes and irregularly placed facets and are more common in colored stones. The jewelry industry does not accept perfected faceted color stones. Most colored stones are faceted just enough to allow illumination. Most faceted gems have three main parts: crown, rondista and pavilion. The crown is the top, the rondista is the narrow section that forms the boundary between the crown and the pavilion; this is the edge of the mounted gems. The pavilion is the bottom. Colored stones usually have facets in the pavilion and crown. The General Formation Process for Color Stones (Previous Technique) The facet of the 'color' gem begins by grinding the rough color gem in the approximate shape and dimensions of the finished stone. This is called preformation. The preform takes an abrasive roughness. The diamond powder is embedded in a nickel plated copper disc, it is the best choice for preforming very hard colored stones (corundum, chrysoberyl, spinel and silicon carbide). Water is the humidifying agent in the preform and the rest of the facet sequence. The lapidaries use various arrangements to keep the wheels wet. The rough preform in the contour of the rondista and the general profile of the crown and pavilion, which leave a surface frosted around the stone. Before grinding in the facets, the lapidary needs to mount the colored stone in an adhesion cup. The procedure is called doping. The stone heats up gently, then rises close to the extreme% of the cup, which has been bathed in molten doped wax. Once the preform has been fixed in the position, it is set aside to cool. The facets of the colored stone are frosted and polished on horizontally rotating wheels called polishing wheels. The lapidaries use a series of cutting polishing wheels with progressively refining diamond powders to grind on the facets, "gradually smoothing off their surfaces, then doing the final polishing on a special polishing wheel. From a variety of materials, the polishing agents with which they are charged are very finely ground powders, which include diamond, corundum, cerium oxide and tin oxide.To cut and polish consistently at the same desired angles, the It holds the cup of adhesion to a device that holds the stone in position as the polishing wheel is found.The traditional mounting device used in many colored stone workshops is the hook or clamp stile.This has a block mounted on a vertical post The adhesion cup fits into a series of holes on the side of the block The position of each hole e a specific angle (from the flat rondista) in which the facet is cut. Returning to the cup of adhesion in the hole, all the facets of a given type are placed at the same angle in its outline around the stone. The Silicon Carbide Gemstone Formation Process Because the beauty of most diamonds depends on scintillation, brilliance and fire (without color), diamond cutters must carefully control the cut factors that affect these characteristics. It is very difficult to place the diamond cuts on the colored gems. Because the refractive index of silicon carbide is greater than that of diamond and colored stones, according to the present invention silicon carbide gems are formed with precision diamond cuts using diamond handling tools known as spikes The spikes allow the cutter to set and adjust the angle of the facet, which is something the cutter can not do with the color stone handling tools, which are present. This is the precision of the diamond handling tools, the dowels, which allows the cutter to use the angles and proportions of a diamond, resulting in "sharp edges" on the silicon carbide gems of the invention. However, because silicon carbide is not as hard as diamond, the polishing wheels of the traditional colored stone are used in the process of • faceting at lower rotational speeds than those speeds typically used for diamond wheels., that is, less than 3000 RPM, and preferably at rotational speeds in the order of 300 RPM. Returning to a more particular description of the silicon carbide forming technique of the invention, the raw gem of silicon carbide is mounted in an adhesion cup and secured within the upper pin. The sharp rondista is cut first on the grinding wheel. This determines the shape of the stone. The table, the flat head is the great facet in the total stone, is then cut using the table spike. The table is then polished using a four-stage process of polishing wheels (discs, wheels or sciaves) that progress from diamond powder sizes from smooth to rough. Polishing can start with a grinding wheel of diamond powder 600 to diamond powder 1200, then with diamond dust 3000 and conclude with a ceramic disk that has an effective diamond dust size of 0.5 to 1 miera, the which is smooth. The cup is then transferred to an upper spike to cut the top side and make the Trim, which consists of 4 Basics (facets). Then the cup is transferred to a lower spike and the lower side is cut into the Trimming which consists of 4 Basics (facets). At this time, the stone is examined by visual inspection to determine its accuracy. After this inspection, the contour of the polishing process of the polishing wheel 4 for the Table is repeated for the Basics. The cup is transferred to the upper spike and the Star facets of the upper side - there are 8 of these cuts along with the Facets of the Upper Rondista (16 facets). The cup is transferred to the lower stem and the Facets of the Lower Rondista (16 facets) are cut. The contour of the polishing process of the polishing wheel 4 for the Table and the Basics is repeated for the remaining facets of the Rondista. The rough gem is now a brilliant round gem, polished and faceted as shown in Figure 3. While the invention has been described in conjunction with certain illustrated embodiments, it will be appreciated that modifications can be made without departing from the true spirit and scope of the invention.

Claims (50)

1. A gem of finished synthetic silicon carbide, characterized in that it comprises a simple synthetic silicon carbide crystal having polished facets with a sufficient degree that allows the intrusion of light into the gem for internal reflection of the interior of the gem.

2. The finished synthetic silicon carbide gem according to claim 1, characterized in that the synthetic silicon carbide has a crystalline structure selected from the group consisting of SiC 6H and SiC 4H.

3. A simulated diamond gem characterized in that it comprises a simple colorless crystal, synthetic silicon carbide having facets polished to a sufficient degree to allow the introduction of light into the gem for internal reflection of the interior of the gem.

4. The simulated diamond gem according to claim 3, characterized in that the facets are characteristic of a diamond cut.

5. The simulated diamond gem according to claim 4, characterized in that the diamond cut is a cut is a round brilliant cut.

6. The simulated diamond gem according to claim 3, characterized in that the silicon carbide s-intético has a crystalline structure selected from the group consisting of SiC 6H and SiC 4H.

7. The simulated diamond gem according to claim 6, characterized in that the colorless synthetic silicon crystal glass is intrinsic silicon carbide.

8. An acivaled synthetic silicon carbide gem characterized in that it has a color comprising a synthetic synthetic silicon carbide skull containing doping atoms at a sufficient concentration that produces a visibly discernible color, the gem has polished facets with a degree enough to allow the introduction of light in the gem for internal reflection of the interior of the gem.

9. The synthetic silicon carbide gem finished in accordance with claim 8, characterized in that it has color, crystal structure and doping characteristics selected from the group consisting of: Structure Characteristics Color Crystalline Impurifier Blue SiC 6H Al-impure Purple SiC 6H Al-impure high Purple SiC 24R N-impure Green SiC 6H N-impure Yellow SiC 3C Pure Yellow-Green SiC 3C N-impure Red SiC 27R N-impure Coffee Light SiC 4H N-impure under Yellow-Orange SiC 8H N-impure.

10. The finished synthetic silicon carbide gem according to claim 8, characterized in that the doping atoms are present in the synthetic silicon carbide crystal at a concentration in the range of about 1015 to 101 carrier atoms per cubic centimeter.

11. The synthetic silicon carbide gem, finished according to claim 9, characterized in that the doping atoms are present in the synthetic silicon carbide crystal at a concentration in the range of about 1015 to 1019 carrier atoms per cubic centimeter.

12. The finished synthetic silicon carbide gem according to claim 8, characterized in that the synthetic silicon carbide has one selected from the group consisting of SiC 6H and SiC 4H.

13. A simulated diamond gem characterized in that it comprises a simple crystal of synthetic, colorless silicon carbide having polished facets with a smooth feature grade of finished diamond gems.

14. The simulated diamond gem according to claim 13, characterized in that the facets are characteristic of a diamond cut.

15. The simulated diamond gem according to claim 14, characterized in that the diamond cut is a round brilliant cut.

, 16. The simulated diamond gem according to claim 13, characterized in that the synthetic silicon carbide has a crystalline structure selected from the group consisting of SiC 6H and SiC 4H.

17. The simulated diamond gem according to claim 16, characterized in that the synthetic, colorless silicon carbide crystal is intrinsic silicon carbide.

18. A method for producing a finished gem having a Mohs hardness of about 8.5-9.25, a density (SG) of about 3.2 and a refractive index of about 2.50-2.71, the method is characterized in that it comprises the steps of: cultivating a simple crystal of a simple polytype of silicon carbide of a character of desired color; and faceting and polishing the silicon carbide crystal in a finished gem.

19. The method according to claim 18, characterized in that it includes the step of cultivating the simple crystal of silicon carbide in a colorless form.

20. The method according to claim 19, characterized in that it includes the step of cultivating the simple crystal of silicon carbide from a crystal in a sublimation system.

21. The method according to claim 19, characterized in that it comprises the step of cultivating the simple crystal as SiC 6H.

22. The method according to claim 21, characterized in that it comprises the step of cultivating the single crystal as intrinsic SiC 6H.

23. The method according to claim 19, characterized in that it comprises the step of cultivating the simple crystal as SiC 4H.

24. The method according to claim 23, characterized in that it comprises the step of cultivating the single crystal as intrinsic SiC 4H.

25. The method in accordance with the claim 18, characterized in that the step of culturing the silicon carbide crystal selectively includes doping the crystal to produce a desired color and shape for the crystal.

26. The method according to claim 25, characterized in that the color of the finished gem, and the crystalline structure and doping characteristics of the silicon carbide crystal producing the color, are selected from the group consisting of: (a) SiC blue 6H, Al-impure; (b) purple SiC 6H, Al-impure, elevated; (c) purple SiC 24R, N-impure; (d) green SiC 6H, N-impure; (e) yellow SiC 3C, pure; (f) yellow-green SiC 3C, N-impure; (g) red SiC 27R, N-impure; (h) light coffee SiC 4H, low N-impure; e (I) yellow-orange SiC 8H, N-impure.

27. The method according to claim 18, characterized in that the faceting and polishing step includes faceting the silicon carbide crystal with diamond cuts.

28. The method according to claim 27, characterized in that the faceting and polishing step includes polishing the facets with diamond powder sizes progressively from large to small.

29. The method according to claim 18, further characterized in that it comprises the step of cutting the single crystal as a culture in a plurality of crude synthetic gems.

30. A method for producing a finished synthetic silicon carbide gem from a silicon carbide crystal, characterized in that it comprises the steps of: cutting a simple crystal of synthetic silicon carbide in a plurality of crude synthetic gems; and faceting and polishing one of the rough synthetic gems in a finished gem.

31. A method for producing a finished simulated diamond gem characterized in that it comprises the steps of: cultivating a simple colorless crystal of a simple polytype of silicon carbide in a glass culture system while keeping the system substantially free of impurity atoms gaseous or vaporized, capable of imparting an undesirable level of color; and faceting and polishing the silicon carbide crystal in a finished gem.

32. The method according to claim 31, characterized in that the faceting and polishing step includes the step of facing the silicon carbide crystal with diamond cuts.

33. The method in accordance with the claim 32, characterized in that the faceting and polishing step includes polishing the facets with diamond powder sizes progressively from large to small.

34. The method in accordance with the claim 33, characterized in that the polishing step includes the use of a polishing wheel with diamond powder sizes progressively from large to small.

35. The method in accordance with the claim 34, characterized in that it includes the step of operating the polishing wheel at speeds below 3000 RPM.

36 '. The method in accordance with the claim 35, characterized in that it includes the step of operating the grinding wheel at speeds in the order of 300 RPM.

37. The method according to claim 31, further characterized in that it comprises the step of cutting the simple crystal as a culture in a plurality of crude synthetic gems.

38. A method for producing a finished simulated diamond gem characterized in that it comprises: cultivating a simple crystal of colorless silicon carbide; and forming and sizing the faceted silicon carbide crystal and polishing the facets with a degree of smooth optical characteristic of finished diamond gems, thereby producing a finished, simulated diamond gem.

39. A simulated diamond gem characterized in that it is produced by the method according to claim 38.

40. The method according to claim 38, characterized in that the final polishing step is carried out with an effective diamond powder size of approximately 0.5-1 microns.

41. A simulated diamond gem characterized in that it is produced by the method according to claim 40.

42. The method, in accordance with the claim 38, characterized in that the formation, dimensioning and polishing are carried out using diamond powder sizes progressively from large to small.

43. A method for producing a finished silicon carbide gem having a visually discernible color, the method is characterized in that it comprises: cultivating a simple crystal of translucent silicon carbide; during the culture stage, of crystal, selectively impurifying the crystal by adding doping atoms capable of giving the crystal a color and shape; and forming and sizing the faceted silicon carbide crystal and polishing the facets with a degree of smooth optical characteristic of finished gems, thereby producing a faceted gem having a visually discernible color.

44. A finished silicon carbide gem, characterized in that it is produced by the method according to claim 43.

45. The method according to claim 43, characterized in that the final polishing step is carried out with an effective diamond powder size of about 0.5-1 microns.

46. A finished gem characterized in that it is produced by the method according to claim 45.

47. The method in accordance with the claim 43, characterized in that the doping atoms are added at concentrations in the range of 1015 to 1019 carrier atoms per cubic centimeter.

48. A method for producing a finished simulated diamond gem characterized in that it comprises: faceting and polishing a rough gem formed from a simple crystal of colorless synthetic silicon carbide to produce a finished simulated diamond gem having shape and polishing characteristics that they allow the light to enter the gem and to be reflected inside the gem.

49. The method according to claim 48, characterized in that the finished simulated diamond gem has a round brilliant shape.

50. The method according to claim 48, characterized in that the synthetic silicon carbide has a crystalline structure selected from the group consisting of SiC 6H and SiC 4H.