Background of The Invention Diamonds are generally polished by hand, substantially in the manner in which they have been polished for centuries. Polishing is achieved by means of gently applying the diamonds against a rotating polishing wheel at various angles. The angles at which the diamond comes into contact with the polishing wheel are dependent upon the type of diamond being polished.

One of the factors determining the quality of the polishing of a diamond is the number of facets formed on the diamond, with quality being related to the number of facets in a directly proportional relationship. The facets must be esthetically and decoratively placed, since a random array of facets, even if enormous in number, will not ensure quality. The number of facets can be increased by decreasing the variation between the subsequent angles at which the diamond is applied to the polishing wheel. Hence, the finer the variations between angles, the greater the number of facets and the higher the quality.

Due to the delicacy and the accuracy involved in the polishing of diamonds, the polishing process requires the use of a steady and firm structure to hold the diamond in a desired position while applying it to the polishing wheel. Two structures that operate in conjunction are currently in use for the purpose of holding the diamond during the polishing process. These structures are commonly referred to as a tang and a dop.

A dop is essentially a structure designed to hold a diamond in place during application against a rotating polishing wheel. The dop must be capable of angular adjustment to enable the diamond which it holds to be applied to the polishing wheel at various angles.

A tang is a structure designed to hold the dop and provide it with a stable, stationary platform. The dop is connected to the tang by a device which enables vertical slanting of the dop in relation to the tang.

Different types of tangs and dops, used for different purposes, are widely known in the art. The combination of the dop and the tang provide a high degree of control over the diamond during the polishing process.

Different tangs and dops are used for the polishing of diamonds of different sizes. Moreover, even while working on the same diamond, different tangs and dops are used for the purpose of polishing different portions of the same diamond.

When working with large diamonds i. e. those of a size of approximately 1 karat after finishing, accuracy and symmetry are crucial factors in achieving good quality of the diamond. Consequently, when such large diamonds are involved, it is important to use a tang and a dop that are very accurate and very stable.

Slanting of the dop connected with the large diamond tang is performed mechanically, using a highly sophisticated fine-tuning mechanism. Several fine- tuning mechanisms are known to the art which comprise an adjustment screw, rotation of which causes the dop to shift its angle in a desired direction. Using the fine-tuning screw mechanism to slant the dop enables the operator to achieve highly accurate faceting angles and near-perfect symmetry, especially when used in conjunction with an angle-measuring device.

However, large diamond tangs, when connected to the required dops and angle adjustment mechanisms, form very heavy, large and crude formations, and are therefore difficult to operate, requiring long training periods for potential polishers.

Such tangs are also very expensive.

On the other hand, although accuracy and symmetry are of significance when working with small diamonds of 30 points or less, after finishing (where 100 points = 1 Karat), they are of lesser significance than when working with large diamonds. This is because it would be nearly impossible for the naked eye to even see the facets of the small diamond, let alone notice any asymmetries.

A very important factor when concerning small diamonds is the production rate. Since small diamonds are used for various day to day products, the demand for small diamonds is very high. To meet the high demand, large amounts of small diamonds need to be produced. This is in direct contrast to large diamonds, for which mass production is not required.

Therefore, it is of great importance that the tangs used in the polishing of small diamonds are light, simple and easy to operate and to hold, otherwise a polisher would have to spend a substantial amount of energy and time over the production of each single small diamond, and therefore would not be able to meet the market demand.

Tangs that are currently used for the polishing of small diamonds are different from those used for the polishing of large diamonds. The former are less expensive and easier to operate, being commonly made of wood, lighter in weight, smaller in size, and simpler in shape. The dops used in conjunction with small diamond tangs are also generally simple and light.

However, a number of disadvantages are associated with currently known small diamond tangs.

One of these disadvantages relates to the fact that tilting of the dop used in the small diamond tang of the prior art is achieved by use of a horizontal hinge which is adjusted manually by application of physical force. The amount of force applied is based on an estimate left to the discretion of the polisher.

Therefore, a polisher operating the small diamond tang of the prior art must learn how to manually adjust the angle of the dop in a very accurate manner merely for the purpose of achieving any faceting, before even attempting to achieve symmetry, or any particular shape. The polisher also has to develop the skill of producing slight angular changes manually, in addition to learning the different shapes of the diamonds and properly operating the polishing wheel. Polishers of small diamonds therefore undergo a training procedure lasting approximately 3-4 months, a large portion of which is devoted to the techniques of adjusting and setting the appropriate working angles.

A second disadvantage relates to the fact that as noted before, quality is related to the number of facets formed on the diamond. Although it is possible to achieve a level of quality sufficient for polishing commonly manufactured small diamonds (e. g. princess cut diamonds depicted in Fig. 2) when working manually, a higher level of quality is extremely difficult, if not impossible, to achieve when working manually, even by highly skilled and highly trained professional polishers.

Therefore, it would be desirable to provide a tang and a dop, working in conjunction for the purpose of polishing small diamonds, that will allow for very slight and accurate angular shifting of the dop, such as are achieved by means of large diamonds tangs, by even relatively inexperienced polishers, while maintaining the characteristics of a small diamond tang. These characteristics include the device being of simple structure, light weight, easy to learn, easy to operate, inexpensive, easily used for mass production of small diamonds, and other characteristics not specified herein, a combination of features that is unavailable according to the prior art.

Summary of the Invention Accordingly, it is an object of the present invention to provide a fine-tunable tang for use in the process of shaping of small diamonds that would facilitate performing slight changes in the angle of a dop connected therewith.

In accordance with a preferred embodiment of the present invention, there is provided a tang for holding a dop during polishing and faceting of small diamonds, the tang comprising a unitary elongated body and an angularly adjustable device mounted within a front portion of said elongated body for attachment thereto of the dop, wherein said angularly adjustable device includes an adjustment screw rotation of said adjustment screw causing fine adjustments to the angle at which said dop is connected to said elongated body.

In the preferred embodiment, the tang comprises an elongated body that widens towards its rear end so as to insure its stability. An angle adjustment device operated by an adjustment screw provides fine angular adjustment of the small diamond dop.

A feature of the present invention is that it is simple to operate by even a relatively inexperienced polisher.

An advantage of the present invention is that it can achieve very accurate angles.

A further advantage of the present invention is that it reduces the training period and training level required from a polisher of small diamonds.

A further advantage of the present invention is that it enables a polisher to achieve very high levels of quality in the shaping of a small diamond, that are unachievable by means of the prior art.

A further advantage of the present invention is that it is inexpensive to produce.

Brief Description of The Drawings For a better understanding of the invention with regard to the embodiments thereof, reference is made to the accompanying drawings, in which like numerals designate corresponding sections or elements throughout, and in which: Fig. 1 is a section drawing of a small diamond tang and dop in accordance with the prior art; Fig. 2 is a section drawing showing several views of a princess cut diamond, made by a small diamond tang and dop, in accordance with the prior art; Fig. 3 is an upper perspective view of a preferred embodiment of the small diamond tang and dop of the present invention; Fig. 4 is an exploded upper perspective view of the small diamond tang and dop of the present invention; Fig. 5 is an exploded lower perspective view of the small diamond tang and dop of the present invention; Fig. 6 is an upper perspective view of an alternative embodiment of the present invention; and Fig. 7 is an exploded view of an angle adjustment device of the small diamond tang and dop of the present invention.

Detailed Description Various types of tang and dop for holding a small diamond during the polishing and faceting process are known to the art. Fig. 1 shows an example of a prior art small diamond tang and dop 10, in which small diamond 16 is gripped by dop 14.

Prior art dop 14 comprises two elongated portions 12, commonly referred to as nails, and a small round stationary anvil 18. Legs 20 of tang 22 are positioned on a stable stationary surface (not shown).

The proper angle at which dop 14 should approach the rotating polishing and faceting wheel (not shown) for the purpose of forming a specific facet is determined and adjusted by the polisher prior to applying diamond 16 to the rotating wheel.

Adjustment of the angle of dop 14 is performed manually by the polisher, by shifting the angle of dop 14 in relation to tang 22. Once the proper angle is determined and adjusted, the end of tang 22, to which dop 14 is connected, is gently lowered towards the rotating shaping wheel.

The angle of dop 14 in relation to tang 22 is adjusted by use of a horizontal hinge 24 that enables vertical movement of dop 14 upon exertion of a small force on dop 14, causing dop 14 to slant to a desired angle. Movements are based on an estimate made by the polisher.

Using the dop 14 and tang 22 of the prior art, even experienced polishers often have considerable difficulty in accurately shaping diamonds, such as the princess-cut diamonds shown in Fig. 2.

The present invention is a small diamond tang and dop working in conjunction with an angle adjustment device to enable simple and accurate adjustment of the angle at which a diamond is presented to a rotating wheel.

Referring now to Figs. 3 to 5, the small diamond tang 30 of the present invention is shown. Small diamond tang 30 comprises a rear portion 32 and a forward portion 34. Rear portion 32 is preferably made of Perspex and forward portion 34 is preferably made of aluminum alloy. It should be noted that other plastic and metal substances with similar qualities will also be suitable such as plastic, and any type of light metal.

Rear portion 32 comprises a wide back end 36, an elongated front end 38, and two legs 40 extending downwards from opposite ends of wide back end 36.

Forward portion 34 comprises an elongated member 42 having a back end 44 and a front end 46, where back end 44 of forward portion 34 is connected to front end 38 of rear portion 32.

Front end 46 of forward portion 34 is provided with an elongated recess 50. A leveling device 48 is attached to front end 46 of forward portion 34. Leveling device 48 comprises a leveling knob 52 and a leveling device 54 positioned within recess 50.

Referring to Figs. 4 and 5, legs 40 comprise leg housing 60 and leveling screw 62. Leveling screw 62 further comprises grip disc 64 and plastic bottom 66. Plastic bottom 66 is mounted on the end of leveling screw 62 on which tang 30 eventually stands. Being made of plastic, plastic bottom 66 enables smoother movement of tang 30 over a stable stationary surface (not shown). Grip disc 64 is screwed over leveling screw 62, until it reaches plastic bottom 66 where it is retained in position. Grip disc 64 provides better grip over leveling screw 62 while screwing and unscrewing it.

Leveling screw 62 is screwed into the lower end of leg housing 60. Horizontal leveling of tang 30 is performed by means of screwing and unscrewing leveling screw 62 of one or both of legs 40, as required.

With reference to Fig. 5, elongated member 42 is a hollow elongated square body having a rounded front end 46 and a rear end 44 provided with two threaded holes 68 alignable with two threaded holes 70 provided in front end 39 of rear portion 32. Rear end 44 of elongated member 42 is fixed to front end 39 of rear portion 32 by two screws 72, inserted through aligned holes 68 and 70.

Leveling device 54 comprises round head 74, a substantially flat region 76 extending from round head 74 which ends in a tail 78, and a leveling screw 80. A slit 82 is provided towards the end of tail 78, and leveling screw 80 narrows sufficiently at its lower end so as to be insertable within slit 82. Leveling screw 80 is able to slant towards and away from round head 74. The height of flat region 76 is equivalent to the height of elongated member 42.

The narrow lower end of leveling screw 80 is provided with a through hole 83 (not shown). Tail 78 is provided with a pair of through holes 84 positioned on either side of slit 82, having dimensions corresponding to that of the through hole of leveling screw 80, such that when screw 80 is inserted within slit 82, hole 83 is aligned with holes 84 and fastenable by a pin inserted through holes 83 and 84.

A spring 92 is positioned over leveling screw 80 so as to be contracted and restricted between the lower face of the top surface 98 and the upper face of the lower surface 100 of elongated member 42. Leveling screw 80 is formed with a threaded upper end 94, extending beyond the upper surface 98 of elongated member 42, for receiving threaded leveling knob 52. Leveling knob 52 has a diameter greater than the width of recess 50, thereby maintaining its position above top surface 98 of elongated member 42.

A hole 86 is formed in flat region 76. A pair of oppositely-arranged through holes 88 are formed on rounded end 46 of elongated member 42, on either side of recess 50. Flat region 76 of leveling device 54 is insertable within recess 50, such that hole 86 is aligned with holes 88. Fastening pin 90 is inserted through holes 86 and 88, fastened by a nut or other fastening device (not shown).

Spring 92 can be described as having two extreme positions, fully extended, and fully contracted. At any given point of time, spring 92 can be in either one of these two extremities or in any position between them. Without any restricting means, spring 92 would always be in its extended position.

Once leveling device 54 is assembled as described above, spring 92 strives to its extended position (within the limits of top side 98 and bottom side 100), thereby pushing against top surface 102 of tail 78. The pressure exerted by spring 92 on tail 78 when it is fully extended, causes leveling device 54 to slant slightly upwards from the horizontal position shown in Fig. 3.

Positioning leveling knob 52 on top of leveling screw 80, achieves two purposes. Firstly, it ensures that leveling screw 80 is retained within recess 50.

Secondly, leveling knob 52 facilitates the adjustments made to the vertical angle of leveling device 54. Rotation of leveling knob 52 in one direction pulls leveling screw 80 through the thread of leveling knob 52, causing contraction of spring 92, thereby causing leveling device 54 to slant downwards. Similarly, rotation of leveling knob 52 in the opposite direction will release spring 92 from its contracted position, thereby causing spring 92 to push against tail 78, which in turn causes leveling device 54 to slant upwards.

In accordance with an alternative embodiment of the present invention shown in Fig 6, leveling device 54 and flat region 76 are fused with the front end of elongated member 42. It should be noted that in accordance with this alternative embodiment tail 78, spring 92, leveling screw 80, fastening pin 90 and leveling knob 52 of Figs. 3-5 are absent, as shown in Fig. 6.

With reference to Fig. 5, round head 74 is formed with a central threaded hole 104 by which angle adjustment device 56 is connected to round head 74, as explained below.

The tang in accordance with the present invention further comprises an angle adjustment device 56, mediating between leveling device 54 and dop 58. With reference to Fig. 7, angle adjustment device 56 further comprises mediator 110, housing 112, spring housing screw 114, spring 116, axis pin 118, axis fixating pin 120, adapter screw 122, angle adjustment screw 124 and angle limiting disc 126.

Mediator 110 has a vertical T shaped base 128 having a horizontal section 132 and a perpendicular section 133, with an elongated screw 130 extending perpendicularly upwards from the center of horizontal section 132 of base 128.

Elongated screw 130 fits into threaded hole 104 of round head 74, thereby connecting angle adjustment device 56 to leveling device 54. Horizontal front section 134 of base 128 is provided with a central through hole 136. The diameter of through hole 136 should be large enough to allow insertion therein of axis pin 118.

Horizontal side section 138 is also formed with a central hole 140 extending at least to the position of through hole 136. The diameter of hole 140 is sufficiently smaller than that of axis pin 118 so as not to weaken axis pin 118 and prevent it from serving as an axis for the angular shifting of dop 58 connected with angle adjustment device 56.

Housing 112 comprises a substantially cylindrical vertical portion 148 and a tapering upper section 150. A u-slot 142 is formed in the middle of cylindrical portion 148. The bottom part of u-slot 142 is a rounded thread 144. Housing 112 is further provided with a horizontal channel 146, positioned on the lower edge of tapered upper portion 150 and extending partially into cylindrical portion 148. The diameter of channel 146 is equal to the diameter of through hole 136 of mediator 110.

A mediating screw 152 extends downwards from the center of the bottom face of cylindrical portion 148 of housing 112, enabling attachment of angle adjustment device 56 to dop 58.

Axis pin 118 is provided with a through hole 154, positioned at longitudinal midpoint of pin 118 and extending perpendicular to the axis of pin 118. The diameter of hole 154 is equal to the diameter of hole 140 formed in horizontal side 138 of mediator 110 and complementary to that of axis fixating screw 120. The length of axis pin 118 is shorter than the diameter of housing 112, such that the ends of axis pin 118 do not extend beyond the edges of housing 112.

Mediator 110 is placed within u-slot 142 with through hole 136 and channel 146 aligned so as to form a single continuous channel. The length of perpendicular section 133 of mediator 110 should be such that when in place, the lower edge 156 of perpendicular section 133 is not in contact with the rounded thread 144 at the bottom of u-slot 142.

Once mediator 110 is in place, axis pin 118 is inserted into the continuous channel formed by through hole 136 and channel 146. Hole 154 of pin 118 is aligned with hole 140 formed in horizontal side of base 128 of mediator 110, to form a continuous channel. Axis fixating pin 120 is then inserted into the continuous channel formed by holes 140 and 154, thereby preventing axis pin 118 from slipping.

Adapter screw 122 is screwed into one side of rounded thread 144 (at this stage it is irrelevant to which of the sides adapter screw 122 is screwed, since the formation is in complete symmetry). Adapter screw 122 is a stationary part that serves as an adapter for angle adjustment screw 124. Adapter screw 122 should not be screwed too deeply into thread 144 since by doing so the angle by which angle adjustment device 56 can slant will be dramatically minimized, as will be explained below.

Spring housing screw 114 is also complementary to thread 144. Spring housing screw 114 is hollow for the purpose of containing spring 116. Spring 116 is inserted into spring housing screw 114 so that part of spring 116 is inside spring housing screw 114, and the rest of it extends therefrom. Spring 114 should be formed of a material that is difficult to contract, such that spring 114 exerts sufficient pressure on housing 112 to cause housing 112 to slant to the maximum possible degree while having a dop 58 holding a small diamond attached thereto.

Once spring 116 is inside spring housing screw 114, spring housing screw 114 is screwed into threaded hole 144 of housing 112 on the opposite side to that of adapter screw 122, so that spring 116 is pressed against the lower edge 156 of perpendicular section 133 of mediator 110. The amount of pressure exerted by spring 116 on edge 156 can be reduced and increased as necessary by screwing and unscrewing spring housing screw 114. The pressure exerted on mediator 110 is transferred to housing 112 to which mediator 110 is connected, thereby causing housing 112 to slant in the direction from which the pressure is provided, up to the maximum degree allowed by angle limiting disc 126.

Angle limiting disc 126 is provided with a central threaded hole 160. The threading of hole 160 is complementary to the thread of elongated screw 130 of mediator 110. Angle limiting disc 126 is screwed over elongated screw 130. The thread of elongated screw 130 does not reach the base 128 of elongated screw 130.

The distance between the end of the thread of elongated screw 130 and the base 128 thereof is determined in accordance with the maximum slanting angle desired.

The closer the end of the threading to the base of elongated screw 130, the narrower the slanting angle of angle adjustment device 56 will be.

In accordance with the preferred embodiment, the threading of elongated screw 130 ceases 1.5 mm above base 132. Instead of using different elongated screws 130 having different thread lengths, angle limiting disc 126 can be screwed up to a desired position on the thread of elongated screw 130. Elongated screw 130 can then be fixed in place by insertion within threaded hole 104 of round head 74 (shown in Fig. 5) up to the position of angle limiting disc 126. Angle limiting disc 126 is then pressed against the bottom face of round head 74, thereby maintaining the desired distance between the end of the thread of elongated screw 130 and base 128 of mediator 110.

Adapter screw 122 is provided with a central threaded channel 162, complementary to the thread of angle adjustment screw 124. Angle adjustment screw 124 may therefore be screwed into channel 162 of adapter screw 122.

When angle adjustment screw 124 is completely unscrewed, housing 112 is slanted in the direction from which pressure is applied by spring 116, as described above. When angle adjustment screw 124 is fully screwed into adapter screw 122, adjustment screw 124 presses against the opposite side 156 of perpendicular section 133 of mediator 110 to that on which pressure is exerted by spring 116, thereby pulling housing 112 towards angle adjustment screw 124 Once angle adjustment device 56 is fully assembled, as described above, there are two opposite sources of pressure exerted one on each side of perpendicular section 133 by spring 116 striving to expand, and angle adjustment screw 124. The pressure exerted by angle adjustment screw 124 is stronger than that exerted by spring 116, since spring 116 will contract in response to counter pressure exerted by angle adjustment screw 124, causing housing 112 to slant in the direction of pressure exerted by angle adjustment screw 124. As angle adjustment screw 124 is unscrewed, spring 116 will be allowed to expand, pulling housing 112 in its direction. Therefore, once angle adjustment device 56 is assembled, the slanting of housing 112 is controlled by angle adjustment screw 124.

For the purpose of shaping small diamonds using the tang of the present invention, a dop 58 is connected to angle adjustment device 56. Generally speaking, any dop known to the art, which may be adapted for use with small diamonds and further adapted to fit onto mediating screw 152 may be used.

In accordance with an alternative embodiment of the present invention, tang 100, angle adjustment device 128 and dop 130 are all integral, permanently connected one with the other.

When using the tang of the present invention, changes in the angle of dop 58 are caused mechanically, by means of rotating angle adjustment screw 124, rather than by inflicting human manual pressure, as was performed in accordance with the small diamonds tangs of the prior art.

As mentioned above, rotation of angle adjustment screw 124 causes the slanting of housing 112, thereby causing attached dop 58 to slant to a desired angle, in a desired direction. These rotations of angle adjustment screw 124 achieve slight angle changes easily, slight changes which were not possible in accordance with the prior art, and other levels of changes that were only achieved by highly experienced polishers. Rotation of angle adjustment screw 124 requires no special skill or training, so even inexperienced personnel can achieve very slight angular changes, thereby achieving very high levels of quality. Moreover, due to the ability to perform slight angular changes that were not possible in accordance with the prior art, the quality of the small diamonds achieved using the tang of the present invention is higher than that obtained using prior art devices.

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, since further modifications will now suggest themselves to those skilled in the art, and it is intended to cover such modifications as fall within the scope of the appended claims.