Patent Publication Number: US-2004050097-A1

Title: Enhanced diamond and method for making same

Description:
FIELD OF THE INVENTION  
       [0001] This invention relates to a method for cutting diamonds and more specifically to a method for cutting round brilliant diamonds having substantially enhanced qualities.  
       BACKGROUND OF THE INVENTION  
       [0002] Throughout centuries many cultures have become fascinated with diamonds. The ancient Greeks and Romans believed diamonds were tears of the Gods and splinters from falling stars. The Hindus who believed in the power of diamonds, placed them in the eyes of some of their statues.  
       [0003] In the 13th century, diamonds began to appear in royal jewelry, usually set as an accent point among pearls in splendid wrought gold. In the Middle Ages and Renaissance period, a ring embellished with an amulet was deemed to bestow magical powers like fearlessness and invincibility upon the wearer. Many believed that diamonds have the power to bring good fortune and the power to interrupt the bad effects of astrological orders. There were many that wore diamonds as charms believing in their ability to heighten sexual prowess and attract others. Plato even wrote about diamonds as living beings, embodying celestial spirits. These myths laid the groundwork for monarchs to begin wearing diamonds as symbols of power.  
       [0004] The first diamond-cutting industry was formed in Venice, a trade capital, starting sometime after 1330. In 1456 Louis de Berqueur discovered how to cut facets of a diamond. By the 16th century the cutting technology had matured enough to produce diamond faceting, which enhances brilliance and fire.  
       [0005] Uncut diamonds appear as transparent to opaque pebbles. However, after cutting, a diamond stone exhibits clarity and luster with fascinating effects of light scattering in prismatic colors. The diamond&#39;s optical characteristic is attributed to its particularly high refractive index and color dispersion.  
       [0006] The optical properties of a cut diamond include: the external brilliance; the internal brilliance: the dispersive brilliance; and the scintillation brilliance. Only when precisely calculated planes and angles are used in the brilliant cut does the stone attain its greatest possible beauty.  
       [0007] Generally, the external brilliance is known as luster, which is produced by the reflection of light on the surface of the facets. The internal brilliance is the refraction and the total reflection of light on the pavilion facets. The dispersive brilliance relates to the splitting or scattering of light into its spectral colors, which is known as the dispersion that evokes the “fire” or “life” in a stone. Finally, the scintillation brilliance is the “sparkle” of the stone when moved, which is caused by the reflections from a light source due to different changes in light incidence.  
       [0008] These optical characteristics are the result of proper diamond cutting. The proportions of various facets and their size play a heavy role in the quality of the final cut diamond. The diamond industry has for decades embraced the concept that an extremely limited set of round brilliant diamond proportions produce maximum brilliance and fire, and as a result, any deviation from this set of proportions would impact the appearance materially.  
       [0009] However, recent advances in diamond research have indicated that other sets of proportions can yield strong-performing diamonds. Thus, there is a need for a new set of proportions that can provide unique diamond qualities, not previously known or expected by those skilled in the art.  
       BRIEF SUMMARY OF THE INVENTION  
       [0010] In accordance with one embodiment of the present invention, a brilliant diamond comprises a crown portion having a plurality of upper main facets and upper girdle facets, said upper girdle facets forming upper girdle intersecting sides and upper main facet intersecting sides. The brilliant diamond also includes a pavilion portion having a plurality of lower main facets and lower girdle facets, which are formed in a substantially aligned arrangement with upper girdle facets. The lower girdle facets include a lower girdle intersecting side and a lower main facet intersecting side. The brilliant diamond also includes a girdle surface in between the crown and pavilion portions. The profile of the girdle surface includes a wide portion at areas of intersection with main facet intersecting sides and a narrow portion at areas of intersection with girdle facet intersecting sides.  
       [0011] In accordance with one embodiment of the invention the ratio of narrow portions over the wide portion is 2:3 or smaller. In accordance with another embodiment of the invention, the ratio of the narrow portions over the wide portions is 1:2.  
       [0012] In accordance with yet another embodiment of the invention the ratio of the narrow portion of the girdle surface to the wide portion is such that the diamond exhibits a first and a second table reflection when observed from the table surface.  
       [0013] In accordance with another embodiment of the invention, the ratio of the narrow portion of the girdle surface to the wide portion is such that the diamond exhibits a plurality of concentric circles with alternating bright and dark reflections. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0014]FIGS. 1 a - 1   d  illustrate various views of a prior art brilliant diamond.  
     [0015]FIGS. 2 a - 2   b  illustrate a side view and a top view of a brilliant diamond in accordance with one embodiment of the invention.  
     [0016]FIG. 3 a  illustrates a profile of a girdle surface of a brilliant diamond in accordance with one embodiment of the invention.  
     [0017]FIG. 3 b  illustrates a profile of a girdle surface of a prior art brilliant diamond.  
     [0018]FIGS. 4 a - 4   b  illustrate a table reflection of a prior art brilliant diamond.  
     [0019]FIGS. 5 a - 5   b  illustrate an exemplary table reflection of a brilliant diamond in accordance with one embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
     [0020] In order to better understand the various techniques employed in accordance with the teachings of the present invention, a brief summary of the important parameters of a diamond cut is explained in reference with FIG. 1 a.    
     [0021]FIG. 1 a  illustrates a prior art brilliant diamond that is cut in accordance with previously known dimensions. The term brilliant relates to the mineral diamond with a “classic” geometry. Its designation applies to the circular form of cut, which exhibits at least 32 facets and a table on the crown, and at least 24 facets and a culet on the pavilion.  
     [0022] To this end, diamond  10  in FIG. 1 a  includes a crown  12  and a pavilion  14 . Crown  12  and pavilion  14  form a girdle  13 . The girdle is the dividing surface between the crown and the pavilion. At least on of its functions is to protect the edge of the stone from damage and fracture. Typically, the girdle is formed as a substantially thin surface, so that it is visible to the naked eye as a narrow line.  
     [0023] The top surface  16  of crown  12  is known as the table facet of the diamond, as illustrated in FIG. 1 b . Star facets  18 , are cut at an angle from table facet  16 . In between star facets  18 , upper main facets  20  are formed having a diameter extending from table facet  16  to the lower portion of crown  12 . Finally, each lower side of each main facet  20  defines an upper girdle facet  22 , having a girdle intersecting side  70  and an upper main facet intersecting side  72 .  
     [0024] Similarly, pavilion  14  includes lower main facets that extend downwardly from the girdle surface towards a central middle culet  32 . FIG. 1 d  illustrates the shape of culet  32  in accordance with a typical diamond cutting method. Pavilion  14  also includes lower girdle facets  34 , which are formed in a substantially aligned arrangement with upper girdle facets  22 , having a girdle intersecting side  80  and a lower main facet intersecting side  82 .  
     [0025] In sum, a brilliant cut includes a crown with one table, 8 star facets, 8 upper main facets, 16 upper girdle facets, a girdle surface, and a pavilion with 8 lower main facets and 16 lower girdle facets. The upper and lower main facets, and the upper and lower girdle facets form 16 points of intersection with girdle surface  13 . The surface of the girdle exhibits a wider thickness at these areas of intersection than its intervening narrow portions. FIG. 1 d  illustrates a pattern of a girdle surface, which appears as a periodic wave with peaks and troughs along its length.  
     [0026]FIG. 2 a  illustrates a diamond in accordance with one embodiment of the invention. A diamond cut in accordance with the principles of the present invention exhibits unique reflective characteristics, not previously achieved by known diamond cutting methods, as will be explained in more detail hereinafter.  
     [0027] The proportions and symmetry ratios employed in accordance with the present invention yield unexpected reflective qualities. In describing various embodiments of the invention, the basis for following a proportion measurement is diameter of girdle  13 . The diameter of the girdle is taken as 100% and other proportions such as the table diameter, total height, girdle thickness, etc. are all measured in comparison to the girdle diameter.  
     [0028] Few brilliant diamonds have a complete circular girdle surface. Usually, diamonds show some deviations from an exact circular form. Typically a girdle is measured in at least four different directions. Measurements are made in millimeters to two decimal places by means of measuring instruments, such as Leveridge Gauge or the Ika Caliper. The lowest and highest values are used as identity marks, and the average value is taken for subsequent percentage calculations. However, the difference between the highest and lowest values is advantageously not greater than 2%, so as to not impair the symmetry of the diamond.  
     [0029] In accordance with one embodiment of the present invention, the table diameter of the diamond as illustrated in FIG. 2 b  is advantageously within the range of 55% to 61% of the girdle diameter. Typically the table is measured in at least two directions from each corner  52  and  54 . The size of the table of a cut diamond influences its brilliance, among other things. It serves to refract as much of the incident light as possible. Furthermore, it allows the light reflected from the pavilion facets to travel to an observer&#39;s eyes.  
     [0030] Furthermore, in accordance with another embodiment of the present invention, the size ratio of the star facets to the upper girdle facet a:b is larger than one and is preferably about 60:40. Typically, if the star facets are larger than the upper girdle facets, the table appears visually smaller than it actually is, and conversely, if the star facets are smaller than the upper girdle facets, the table appears larger.  
     [0031] Another property measured in accordance with one embodiment of the invention is the crown angle. This angle is defined as the angle between the main crown facets in relation to the girdle plane. This angle is advantageously within a range of 33.5° to 35°, however, the invention is not limited in scope in that respect. The crown height, which is the height measured from the girdle plane to the top of the diamond is about 13.5% to 14.6%, although the invention is not limited in scope in that respect.  
     [0032] In accordance with one embodiment of the invention, the pavilion depth is larger than 40% and preferably around 43%. A pavilion angle of 40° to 41° is a preferable dimension in accordance with one embodiment of the invention.  
     [0033]FIG. 3 a  illustrates the girdle profile of a diamond in accordance with one embodiment of the invention. As illustrated in FIG. 2 a , each upper girdle facet  22   a  joins the next upper girdle facet  22   a  along girdle intersecting side  70 . Each upper girdle facet  22   a  also joins an upper main facet  20   a  along main facet intersecting side  72 . The intersection of sides  72  of upper main facets with the girdle surface forms a wider area than the intersection of sides  70  with the girdle facet.  
     [0034] In order to form a narrow surface area along the girdle surface, each upper girdle facet is cut at a deeper angle near the vicinity of sides  70  than the angle near the vicinity of side  72 . Thus, the surface angle between two upper girdle facets tends to flatten (get closer to 180°), and becomes flatter than the angle between an upper girdle and its adjoining upper main facet.  
     [0035] In accordance with one embodiment of the invention, the ratio of thickness between the narrower area of the girdle surface to its wider area d:e is about 2:3 or less. However, the invention is not limited in scope in that respect, and other ratios may be acceptable, such as 1:2 or less, as will be discussed in more detail later.  
     [0036] It is noted that the girdle surface of the present invention is different than the girdle surface of prior art diamonds. For example, as illustrated in FIG. 3 b , the prior art diamonds form a wider portion on the girdle surface at the intersection of the two upper girdle facets, and at the intersection of an upper girdle facet and an upper main facet. As stated above, the girdle surface exhibits 16 points of intersection with a wider dimension. However, the girdle surface of the present invention exhibits 8 points of intersection with a wider dimension.  
     [0037] In accordance with another embodiment of the invention, the lower girdle facets are cut based on the same principles that the upper girdle facets are formed. To this end, each lower girdle facet  34   a  joins the next lower girdle facet  34   a  along a girdle intersecting side  80 . Each lower girdle facet  34   a  also joins a lower main facet  30   a  along a lower main facet intersecting side  82 . The intersection of sides  82  of lower main facets with the girdle surface forms a wider area than the intersection of sides  80  with the girdle surface.  
     [0038] In order to form a narrow surface area along the girdle surface, each lower girdle facet is cut at a deeper angle near the vicinity of sides  80  than the angle near the vicinity of side  82 . Thus, the angle between two lower girdle facets tends to flatten (get closer to 180°), and becomes flatter than the angle between a lower girdle and its adjoining lower main facet.  
     [0039] A diamond cut in accordance with the present invention exhibits a unique and powerful light reflection as explained hereinafter. In order to better appreciate the reflection pattern of the brilliant diamond cut in accordance with the principles of the present invention, a review of a reflection pattern for a prior art diamond is first explained.  
     [0040]FIGS. 4 a - 4   b  illustrate an appearance of a prior art diamond observed at right angles to the table surface. An observer sees in the pavilion of the stone just above the culet a low brilliance zone, which is caused by the reflection of the table, which is surrounded by light to dark gray reflections of the star facets. The brilliance zone forms a circular surface, which lies in a plane parallel to the table surface. These reflections are most clearly visible with dark field lighting, when the light enters the stone through the sides of the pavilion.  
     [0041] The ultimate appearance of the prior art diamond of FIG. 4 a - 4   b  is a pattern that resembles a wheel, with a central dark area, like a “hub” and 8 dark “spokes” that are the reflections of the pavilion main facets.  
     [0042] In a sharp contrast, FIGS. 5 a - 5   b  illustrate an appearance of a diamond, in accordance with one embodiment of the invention, observed at right angles to the table surface. In contrast with FIG. 4 a , the diamond creates a pattern, which includes a circle of bright reflections of the star facets around the inside edge of the table, and a second set of similar reflections appearing through the upper girdle facets.  
     [0043] Furthermore, in addition to a first table reflection region  106 , a second table reflection region  108  is formed. Thus, the pattern in the diamond looks like concentric circles, alternating bright and dark. The combination of the high degree of contrast and the symmetrical balance is quite striking. In order to achieve the reflective characteristics of the diamond as illustrated in FIG. 5 b  the angle between two adjoining girdle facets is adjusted, which in turn results in varying the length ratio between the narrower portions of the girdle surface to its wider portions.  
     [0044] In accordance with one embodiment of the invention. as illustrated in FIGS. 5 a  and  5   b , the height of the lower girdle facets extends long enough to overlap or break up the primary table reflection. Thus, if each lower girdle facet  34  is considered as a triangle, the length of the sides and the height of the triangle is configured to be long enough so that the triangles extend to either become adjacent to the primary table reflection or overlap into the primary table reflection.  
     [0045] This multiple reflective pattern remarkably provides the basis for strong scintillation as the diamond, the light source, or the observer moves. In accordance with one embodiment of the invention, the overall visual impact of this pattern is even stronger when the diamond is mounted. Furthermore, diamonds cut in accordance with the principles of the present invention provide light return and fire, that is above the levels produced by prior art diamonds.  
     [0046] Thus, a brilliant diamond created in accordance with the principles of the present invention provides a unique reflective characteristics include multiple reflections and unexpected scintillation quality.  
     [0047] It is noted that although specific embodiments have been discussed, the invention is not limited in scope to such embodiments. Various modifications and applications may be employed without departing from the true spirit and scope of the invention.