Abstract:
A method for preparing a diamond having a six-pointed-star shaped girdle comprising: (1) providing a round diamond; and (2) grooving six equally spaced, equally-sized triangularly-shaped 120° angled grooves in the girdle of the round diamond. Also disclosed is a grooving machine comprising a dop, wherein the dop may be rotated between six equally-spaced stops.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a method for grooving diamonds.  
         BACKGROUND OF THE INVENTION  
         [0002]    The value of a diamond is determined by several parameters. These include: shape, color, clarity, weight and polish. With respect to shape, the more accepted shape types are brilliant cut, radiant cut, princess cut, heart shape cut, pear shape cut, oval cut, marquise cut, emerald cut and trillion cut. Currently, the round brilliant cut is considered the most popular shape for a diamond.  
           [0003]    The shape of the finished diamond is generally determined by the condition and shape of the rough crystal form which the diamond is cut. The decision on how to cut the rough crystal takes into account all of the above parameters, so as to obtain a diamond of maximum value. It is generally not accepted to cut a finished diamond, since the loss in weight reduces its value.  
           [0004]    Diamonds are generally cut by a rapidly rotating disk impregnated with diamond dust. In the event that it is desired to cut a groove in the diamond, as in the heart-shaped cut, discs of successively wider cutting edge angles are used in order to cut the cleavage of the heart shape. Another cutting technique currently in use is cutting by a laser.  
           [0005]    The ‘Star of David’ or ‘Shield of David’ is a symbol associated with the Jewish religion, as well as having a distinctive shape in its own right. It is a six-pointed star which may be formed by two superimposed triangles, one of which is rotated 180° with respect to the other. The Star of David is a popular shape in jewelry and brooches.  
           [0006]    Diamonds are marketed which have a Star of David shape. These diamonds are cut from rough crystals whose natural, uncut shape is fortuitously similar to a Star of David. In order to lose the least amount of weight in the cutting process, such a crystal is cut in the shape of a Star of David. Since finding such a shaped crystal is rare, diamonds which have a Star of David shape are also rare. Such shaped diamonds are never cut from finished diamonds.  
           [0007]    A piece of jewelry is known which is in the shape of a Star of David. In this product, a number of triangularly shaped diamonds are inlaid in the jewelry to form the Star of David shape.  
         SUMMARY OF THE INVENTION  
         [0008]    It is an object of the invention to provide a method for preparing a diamond which exhibits the shape of a Star of David.  
           [0009]    It is a further object of the invention to provide a diamond prepared by the method of the invention.  
           [0010]    Thus, the present invention provides a method for preparing a diamond having a six-pointed-star shaped girdle comprising:  
           [0011]    (i) providing a round diamond; and  
           [0012]    (ii) grooving six equally spaced, equally-sized triangularly-shaped 120° angled grooves in the girdle of said round diamond.  
           [0013]    The present invention provides a repeatable method for preparing a diamond having a Star of David shape. The method does not depend on finding by chance a particularly shaped rough crystal.  
           [0014]    The following terms appearing in the present specification have the following meanings:  
           [0015]    Grooving—cutting a groove in the diamond, thereby extricating material from the diamond;  
           [0016]    Grooving machine—a machine for grooving the diamond. The machine cuts with a grooving wheel (disc) having a tapered edge;  
           [0017]    Round diamond—a finished diamond having a spherical shape;  
           [0018]    Girdle—facets of a diamond on its widest edge;  
           [0019]    Pavilion—lower portion of the diamond below the girdle;  
           [0020]    Crown—the upper portion of the diamond above the girdle.  
           [0021]    The present invention also provides a six-pointed-star shaped diamond shaped by the method of the invention.  
           [0022]    Also included in the invention is a grooving machine in which the dop may be rotated between six equally-spaced stops, rather than the conventional eight. This allows the cutting of six equally-spaced grooves in the diamond in accordance with the method of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0023]    In order to understand the invention and to see how it may be carried out in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:  
         [0024]    [0024]FIG. 1 is a perspective side view of a prior art round diamond;  
         [0025]    [0025]FIGS. 2, 3 &amp;  4  are top views of the diamond of FIG. 1;  
         [0026]    [0026]FIGS. 5 &amp; 6 are bottom views of the diamond of FIG. 1;  
         [0027]    [0027]FIG. 7 is a top view of a diamond prepared according to one embodiment of the method of the invention;  
         [0028]    [0028]FIG. 8 is a bottom view of the diamond of FIG. 7; and  
         [0029]    [0029]FIGS. 9 a - 9   g  illustrate various sequential steps in one embodiment of the method of the invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0030]    Referring now to FIG. 1, a brilliant-type round diamond, generally designated  2 , is shown. The diamond comprises an upper portion  4  termed the crown, a lower portion  6  termed the pavilion, and a medial ring of facets  8  termed the girdle, intermediate between the crown and the pavilion. The facets of the crown  4  are termed a table facet  10  on its horizontal upper side, star facets  12  adjacent the table facet, bezel facets  14  intermediate between the star facets and upper girdle facets  16  contiguous with the upper edge of the girdle  8 . The facets of the pavilion are termed lower girdle facets  18  contiguous with the lower edge of the girdle, and pavilion facets  20  extending from the girdle to the bottom point of the diamond, termed the culet  22 .  
         [0031]    A diamond viewed from above is shown in FIGS. 2, 3,  4  and  7 . The table  10 , star  12 , bezel  14  and upper girdle  16  facets are visible, as well as the upper edges of the girdle facets  8 . The method of the invention comprises grooving six equally spaced, equally-sized triangularly-shaped 120° angled grooves in the girdle of the diamond. The first of the grooves is cut opposite a specified point in the crown. Preferably, the point is either a point  24  on the girdle opposite the center  26  of a bezel facet, or a point  28  on the girdle opposite the common rib line  30  of two adjoining upper girdle facets  16 . FIG. 3 shows the cut out portions  32  of the diamond (shaded) when the initial grooving point is opposite the common rib line  30 , and FIG. 4 shows the cut out portion  34  (shaded) when the initial grooving point  24  is opposite the center  26  of the bezel facet. FIGS. 5 and 6 show the respective cuts of FIGS. 3 and 4 viewed from below.  
         [0032]    [0032]FIG. 7 shows the diamond of FIG. 4 after the grooves have been removed. A groove  50  is triangularly shaped with an obtuse angle  52  of 120°. The depth  54  and the width  56  of the groove is substantially equivalent in each of the grooves so that they are equally sized, and they are spaced at substantially equal distances one from the other. FIG. 8 shows the diamond of FIG. 7 from below, in which can be seen the lower girdle  18  and pavilion  20  facets, and the culet  22 .  
         [0033]    The grooving is carried out by a grooving machine. The disc of the grooving machine may have a wedge-shaped, tapered edge which creates the 120° angle of the groove. Although initially the disc enters the diamond at the girdle, as the disc progresses into the diamond, the groove spreads to the crown and pavilion. Preferably, the girdle of the diamond is held perpendicularly to the plane of the disc.  
         [0034]    [0034]FIGS. 9 a - 9   g  illustrate one embodiment of the method of the invention. In FIG. 9 a , a round diamond  60  is held in a dop, and a first position  62  of the diamond is positioned above the rotating disc  64 . In this embodiment, the first position is opposite the center  66  of a bezel facet.  
         [0035]    In FIG. 9 b , a first 120° groove  66  is cut at the first position. The dop holding the diamond is then rotated (FIG. 9 c ) above the disc  64  to a second position 180° from the first position, and a second 120° groove  68  is cut in the diamond. The diamond is rotated (FIG. 9 d ) to a third position 60° from the second position, and a third 120° groove  70  is cut. The diamond is further rotated (FIG. 9 e ) to a fourth position 180° from the third position, and a fourth 120° groove  72  is cut. The diamond is then rotated (FIG. 9 f ) to a fifth position 60° from the fourth position, and a fifth 120° groove  74  is cut. Finally, the diamond is rotated (FIG. 9 g ) to a sixth position 180° from the fifth position, and a sixth 120° groove  76  is cut, resulting in the six-pointed Star of David shape.