Abstract:
The invention discloses a composite gemstone for use in jewelry, formed of two or more adjacent precious stones, bonded to one another in a permanent manner without use of adhesive. The appearance is that of a single homogenous stone, with high grade optical properties as measured spectroscopically. “Low height” diamonds may be used for forming the composite, when to date such low height diamonds are considered non-profitable for jewelry. A process for the production of such composite gemstones is disclosed.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to jewelry including gemstones, especially diamonds. More particularly, the invention relates to composite stones which give the appearance of a single precious stone. 
       BACKGROUND 
       [0002]    Many attempts have been made to lower costs of jewelry featuring cut diamonds, and to make smaller sized diamonds appear larger than they truly are. These include settings which show several small stones typically contacting each other side by side, to appear to be a single stone. This is termed a “composite stone”. PCT Publication No. WO2012/013246 to Iter Eyal, describes a gemstone setting in which at least three small stones give the appearance of one large stone. This setting, best shown in  FIGS. 3A-3B , includes an upper composite stone, and a lower stone, while the center of the setting may have a hollow area representing a saving in costs, as compared to that of a single large stone of similar size. 
         [0003]    Prior art attempts at forming composite diamond jewelry, such as shown in WO2012/013246, are prone to separation and shifting of the individual stones that form the composite. This is due to the structural nature of diamonds, whose highly smooth nature prevents adhesives from sticking to the surfaces. Prior art composite stones tend to fall apart with passing of time as the adhesive fails and jostling of the stones occurs during normal display of the stones when the jewelry is worn by a consumer. Additionally, after prolonged wear, humidity and residues tend to enter between the stones and prevent reflective light from entering, eliminating the sparkle associated with genuine single stone diamonds. 
         [0004]    It is an object of the invention to provide a method of producing composite stones, resulting in effectively permanent adherence of the individual stones to one another, without weakening seen in prior art composite stones. 
         [0005]    Fancy colored diamonds are diamonds having rare glossy colors such as vivid blue, vivid orange or red, and are far more costly than transparent diamonds. For instance, while a white diamond of 1 carat and highest clarity is typically valued at $25,000, in contrast, a vivid red stone of similar quality is valued at $1,000,000. It would be desirable to create the effect of a large colored diamond, using a small colored diamond as part of a composite stone which includes other, less costly, transparent diamonds. 
         [0006]    A rough diamond having less height than 4 mm will typically produce a finished diamond in a low price category. A rough diamond having less height less than 2 mm results in little profit, as it is typically used to produce tiny diamonds known as “mellies”, to create diamond dust as an abrasive, or to form cutting tools, depending on several variables such as height verses diameter, etc. 
         [0007]    It would be desirable to utilize such rough diamonds having less height than 5 mm, to create jewelry, as the cost of such stones in the diamond industry is estimated at $4000 per carat for an absolute quality stone as opposed to $15,000 for a single stone of identical quality. Therefore, the resultant jewelry made from such relatively “low height” diamonds would be considerably less expensive and more readily attainable. 
         [0008]    It is an object of the present invention to create a composite gemstone, which utilizes gemstones of a relatively low height which have not been used in jewelry to date. The composite stones of the invention can additionally include fancy colored stones and can give the appearance of a large fancy colored stone, while actually containing only a small fancy colored stone. These and other objects and advantages of the invention will become more apparent from the Detailed Description of the Invention that follows. 
       SUMMARY OF THE INVENTION 
       [0009]    The invention provides a composite gemstone comprised of an upper precious stone and a lower precious stone, bonded to one another permanently without use of adhesive, wherein the contact points of the upper stone and the lower stone are highly polished; wherein the visual appearance is of a single gemstone. 
         [0010]    In some instances, the upper and the lower precious stones are bonded by means of vacuum. The vacuum may be an absolute vacuum formed using a casimir effect. 
         [0011]    In certain embodiments, the upper precious stone and the lower precious stone may be selected independently from a material of the following group: diamond, sapphire, spinel, topaz, quartz and spinel. 
         [0012]    In one embodiment, one or both of the lower precious stone and the upper precious stone are low height diamonds, wherein the height of the rough stone is within the approximate range of 1.5-3.8 mm prior to cutting. 
         [0013]    Alternatively, the height of at least one of the lower and upper precious stones is 4.8 mm. 
         [0014]    Moreover, in some embodiments, at least one of the precious stones is a fancy colored diamond. 
         [0015]    Optionally, a ratio of 63% of height to diameter is maintained in the composite for optimal light refraction. 
         [0016]    Preferably, the composite comprises matched facets between the upper and the lower precious stones. 
         [0017]    The invention further provides a composite gemstone having two or more precious stones bonded to one another permanently without use of adhesive, produced using the following process:
       a) providing two or more precious stones as a matched set, for use in a single composite stone, wherein the stones are polished and cut to desired geometrical sizes and shapes;   b) clamping each of the precious stones so as to expose surfaces which will be bonded to adjacent precious stones in the composite; and rotating the precious stones at approximately 2000-4000 RPM, while polishing the exposed surfaces of the precious stones;   c) cleaning the precious stones;   d) clamping the precious stones and rotating the precious stones at a speed of approximately 500-1500 RPM in opposite rotational orientation; contacting the precious stones with one another at a desired orientation until vacuum is sensed; halting the rotation;
           thus obtaining a composite gemstone having two or more precious stones bonded together in a permanent manner without use of adhesive.   
               
 
         [0023]    In some embodiments, in step b) the precious stones are polished until a nano-surface smoothness is obtained. 
         [0024]    In some embodiments, the precious stones are maintained in sterile conditions after step c) is performed until step d) is begun. 
         [0025]    In certain instances, step c) of cleaning comprises boiling the stones overnight in a mixture of hydrochloric acid, sulfuric acid and cyanide, followed by rinsing in distilled water. 
         [0026]    In one embodiment, in step d) the precious stones contact one another at a pressure of 10 PSI. 
         [0027]    The invention also provides a process for preparing a composite gemstone having two or more precious stones bonded to one another permanently without use of adhesive, the process comprising:
       a) providing two or more precious stones as a matched set, for use in a single composite stone, wherein the stones are polished and cut to desired geometrical sizes and shapes;   b) clamping each of the precious stones so as to expose surfaces which will be bonded to adjacent precious stones in the composite; and rotating the precious stones at approximately 2000-4000 RPM, while polishing the exposed surfaces of the precious stones;   c) cleaning the precious stones;   d) clamping the precious stones and rotating the precious stones at a speed of approximately 500-1500 RPM in opposite rotational orientation; contacting the precious stones with one another at a desired orientation until vacuum is sensed; halting the rotation;
           thus obtaining a composite gemstone having two or more precious stones bonded together in a permanent manner without use of adhesive.   
               
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0033]    The present invention is illustrated by way of example in the figures of the accompanying drawings, in which like references indicate similar elements and in which: 
           [0034]      FIG. 1  illustrates a jewelry item comprising a composite stone, having an upper stone bonded to a lower stone, and mounted in a ring. The composite stone is formed of two low height diamonds. 
           [0035]      FIG. 2  is the ring of  FIG. 1 , shown in exploded side view. 
           [0036]      FIG. 3  shows a graph of Gemex® spectrophotometer results for analysis of two composite diamonds of the invention, indicating high grade of light refraction for the composite gems of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. There is no intention to limit the invention to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. 
         [0038]    The invention allows production of composite stone jewelry utilizing precious stones such as diamonds, having approximately 1.5-3.8 mm in height. This height is considered to date to be too low for use in the jewelry industry to form finished stones that have the appearance of a single large stone. 
         [0039]    The present invention provides use of two stones, an upper stone and a lower stone, to form a composite stone. After manufacture using the method of the invention (described herein below), upper stone and lower stone are permanently bound together even prior to mounting in a setting, and the bond will not weaken with time. The bond is sufficiently strong to prevent residues from entering between the stone, thus the brilliance achieved is permanent. 
         [0040]    Referring to  FIG. 1 , jewelry item  100  comprises a base  110 , a mount  120  and a composite gem  130 . While jewelry item  100  is illustrated as a ring, this is an example only, and the jewelry item  100  may be of any form used as an adornment, such as a brooch, a ring, a necklace, earrings, a bracelet, and a pendant. The base  110  may be used to link, connect, attach or be worn. 
         [0041]    The mount  120  may comprise a plurality of prongs  160  having upper ends  162  and supports  164  designed to hold a girdle  180  of the composite gem  130 . 
         [0042]    The composite gem  130  comprises an upper stone  140  and a lower stone  150  bound together and giving the visual impression of an integral gem. 
         [0043]    While the drawings show the upper stone  140  generally shaped as a crown and the bottom part  150  shaped as a pavilion, any other known and/or conceived shape is intended to be included in the scope and spirit of the present disclosure. 
         [0044]    Upper stone  140  comprises a bottom face  190 , while the lower stone  150  comprises a top face  200 . The bottom face  190  and the top face  200  are highly polished and smooth, and in the final step of the manufacturing method described below, when both are brought into contact with one another, an attraction force maintains a bond between the bottom face  190  and the top face  200 . This nulls any need for adhesives, and the composite gem  130  appears as a homogeneous gem. 
         [0045]    Referring to  FIG. 2 , an exploded side view is shown, illustrating jewelry item  400  which includes a composite gem  430  formed of an upper stone  440 , and a lower stone  450 . The jewelry item  400  includes a mount  420 , and a base  110  which in  FIG. 2  is a ring shown in side view. 
         [0046]    The bottom face  490  of the upper stone  440  contacts and is bound to the top face  500  of the lower stone  450 , in a permanent manner without use of adhesive, and no weakening of the bond occurs over time. The upper and lower stone remain bonded even without the presence of the mount  420 . 
         [0047]    The composite gem of the invention may be produced from separate precious stones, cut to any conceivable shape and size. Shapes include for instance, oval, conical, cylindrical, elliptical, pyramidal, monoclinic, triclinic, hexagonal, tetragonal, triclinic, orthorhombic, aggregate, or the like or combinations thereof. 
         [0048]    The plurality of stones used for the composite may consist of the same material, or of different materials. As diamonds are highest in cost, use of the invention to form composite diamonds, represents the most savings. However any precious or semiprecious composite stone may be produced. The stones may be polished in any conceivable, known or developed cut known in the industry. 
         [0049]    In order to obtain a typical diamond of a two carat size, in prior art the total height needs to be 5 mm. However, using the composite stone of the invention, a two carat appearance stone may be obtained using an upper stone with a height of 1.5 mm, and a lower stone with a height of 3.5 mm thus resulting in a 2 carat diamond in weight as well as appearance, at a fraction of the cost than that of a typical single stone. 
         [0050]    In prior art, in order to obtain a typical 5 carat stone, the total height needs to be 7 mm, with the stone having a geometrical round shape. 
         [0051]    Using the composite stone of the invention, the height of the lower stone may be 4.8 mm, with the remaining height coming from the upper stone. 
         [0052]    When a 4.8 mm height stone is utilized, prior art methods would result in a final polished diamond of only 1 carat. In contrast, the composite stone of the invention having a 4.8 mm height as the bottom stone and an additional upper stone having 2.2 mm would allow a 5 carat polished stone to be produced comprising of an upper and lower diamond. The difference in price is several hundred thousand dollars. 
         [0053]    While upper or lower stones may be used with a height which is greater than 4 mm, resulting in a large composite stone, typically the inventor uses stones with a height of around 3 mm. 
         [0054]    Some stones, while being fairly large, are not high enough and may only have a height of 2.5 mm. In prior art, these stones would be only crushed to small diamonds, and would make little or no profit. In contrast, such a “low height” stone can be used in the composite of the invention as the upper stone and sold for a considerably high profit. 
         [0055]    In one embodiment, the diameters of the stones utilized may range from 4 mm to 16 mm. 
       EXAMPLE 1 
     Composites of the Invention Have High Refractive Qualities 
       [0056]    A composite stone was created, using a matched pair of diamonds, cut in a Modern Brilliant cut. The upper stone was 1.1 mm in height total, 6.4 mm in diameter, giving less than 0.2 mm surface area for clamping using a dope, which represents a miniaturization difficulty overcome by the inventor using the production method described below. The crown of the upper stone was cut at a 32 degree angle, to ascertain a proper Modern Brilliant cut, without deleterious Rainbow effect. The inventors ascertain that a ratio of 63% of height to diameter is maintained, to assure light refraction is optimal in the final composite, without a unattractive fisheye effect. In prior art composite stones this ratio has not been maintained and observed, with the end result being composite stones which have poor measurements for brilliancy. 
         [0057]    Additionally, the facets on the upper and lower stones which form the composite are matched so as to ensure ideal relative placement relative to one another (e.g. star facet upon on upper stone opposite a tie facet on a lower stone) which will give ideal light refraction as in a single homogeneous stone. 
         [0058]    Referring to  FIG. 3 , two composite diamonds of the invention were scientifically analyzed by the Gemex® spectrophotometer, to measure the amount of bright white light (known as Brilliance), bright color light (known as Fire) and scintillation (known as Sparkle) for the specific composite diamonds. These measurements correlate with the number of points of light that turn on and off as the diamond moves. The diamonds were measured by spectrophotometer at multiple light angles. 
         [0059]    Prior art composite stones typically measure optically at “poor”, and prior art homogenous single stones of similar size described in Example 1 typically receive a rating of “good” or “very good” 
         [0060]    In contrast, The Gemex® results shown in  FIG. 3  indicate that the two composites made according to Example 1 received “High” and “Very High” ratings for Brilliance, Fire and Sparkle, showing high quality light refraction associated with diamonds deemed attractive in appearance in the industry. 
       EXAMPLE 2 
     Fancy Colored Composites 
       [0061]    The lower stone may be selected to be a red diamond, having a diameter of 6.5 mm but only a 3 mm height resulting in a 1 carat diamond in weight and appearance. 
         [0062]    In contrast, cutting and polishing this same size stone using prior art methods, would produce a finished stone of less than half a carat, equated with a huge difference in price. 
         [0063]    The inventor binds an upper white diamond having 40% of the weight of that of the final composite, giving the appearance of a single red diamond. The consumer cost is only 1/10th of that of a single homogenous red diamond. 
       Production Method-Overview 
       [0064]    The production method of the invention aims to bind the upper and lower stone to one another, in a permanent manner without adhesives. The highly polished diamond surfaces are joined indefinitely by inducing an absolute vacuum, termed in physics the “Casimir effect”. This effect is achieved under the following conditions: 
         [0065]    1) The two surfaces desired to be joined have a nano-smooth surface. In a presently preferred embodiment the surfaces are polished flat to within a tolerance of one millionth of an Inch. 
         [0066]    2) Friction must be induced to reach a complete vacuum (Casimir effect), at which point the two surfaces to be joined are brought into sliding contact. Once a vacuum is achieved, the composite stone is brought to a sudden stop. 
         [0067]    The bond can only be broken by sliding the stones apart using massive force, or by applying direct heat exceeding 400 degrees Celsius, which would result in heat expansion. Pulling the stones apart would be impossible without damaging the stones. 
       Production Process 
       [0068]    Stage 1) The initial processing from a rough diamond. This rough stone is selected to have particular traits suitable for the desired product production. The desired rough is selected from many rough types, as rough diamonds come in many shapes and must undergo a sorting process. They are scanned by computer, categorized and go on to the following stage. This stage is termed the “provisional stage.” 
         [0069]    Stage 2) The stones are then matched to pairs temporarily, and polished to the desired shape. The paired stones are selected to have a similar diameter, and ratio of height to diameter. 
         [0070]    Stage 3) The stones are cut by laser into the desired geometrical shape and to the desired size. The paired upper and lower stones are cut in such a way that the optical refraction will be identical to that of a single stone. The appearance and weight density are identical to a single stone. 
         [0071]    Stage 4) The stones are then placed on a bruiting machine which eliminates the burned surface of the diamond caused by the laser while simultaneously accurately bringing the stone to the desired diameter size. 
         [0072]    Stage 5) The stones are placed in specially designed holding pins and held up against a rapidly moving diamond wheel at 2000-4,000 RPM, and specially fine diamond dust is applied for polishing. This acts to shape and polish the diamond to a super-smooth “nano-surface”, namely polished flat to within a tolerance of one millionth of an Inch. Prior art polishing diamond dust for polishing is far more coarse grain compared to the diamond powder utilized in the presently preferred embodiment. The two stones, upper and lower are processed from the beginning as sets thus eliminating odd sets at the end of the production stages. After the cutting and polishing stages are completed the diamond are separated for a cleaning process, boiled overnight in Hydrochloric acid, sulfuric acid and cyanide and then rinsed thoroughly in boiling distilled water. The stones are then held in sterile conditions until Stage 6 step is performed. The two stones are ready to be joined indefinitely by creating a vacuum between the two diamonds achieved by a device developed by the inventor. 
         [0073]    Stage 6) To form a permanent bond between two such small stones having a relatively small surface space, the desired vacuum was reached by having each stone clamped while spun at 1,500 RPM using an electric stepper motor modified to our standards and needs. One stone spins clockwise and the second stone spins counter clockwise while they are pressed up against each other at 10 PSI. A sensor is attached to the holder of each stone so that as soon as the vacuum is achieved the spin comes to an immediate stop. At least one heat sensor additionally measures the friction forces present during processing. Once the connection is complete the composite stone is now bonded, and is released from the clamps to undergo a cleaning process and be mounted in a jewelry item as desired. 
         [0074]    Having described the invention with regard to certain specific embodiments thereof, it is to be understood that the description is not meant as a limitation, as further modifications will now become apparent to those skilled in the art, and it is intended to cover such modifications as are within the scope of the appended claims.