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Title:
APPARATUS FOR CUTTING, POLISHING AND PROCESSING OF GEMSTONES
Document Type and Number:
WIPO Patent Application WO/2018/016966
Kind Code:
A1
Abstract:
Gemstone cutting and polishing apparatus comprising two main components: a precision divider (100) and an angle and elevation platform (200). The precision divider (100) is arranged to cut and polish a desired number of facets in a gemstone with high precision. The precision (100) divider is attached, preferably releasable, pivotal to the angle and elevation platform (200). The precision divider (100)can be positioned and locked in an angle between 0° and 90° withrespect to the horizontal level, to produce precisely cut facets in the gemstone with desired angles. The precision divider (100) is provided with an improved dopstick receptacle (106) with a non-circular cross-section, and a correspondingly shaped dopstick (500, 503), thus providing a highly fixed and stable attachment of the gemstone being processed.

Inventors:
ALVES-FILHO, Odilio (Elvevegen 25, 7031 Trondheim, 7031, NO)
Application Number:
NO2017/050192
Publication Date:
January 25, 2018
Filing Date:
July 14, 2017
Export Citation:
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Assignee:
ALVES-FILHO, Odilio (Elvevegen 25, 7031 Trondheim, 7031, NO)
International Classes:
B24B9/16; B24B19/16; B28D5/00
Attorney, Agent or Firm:
CURO AS (Vestre Rosten 81, 7075 Tiller, 7075, NO)
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Claims:
Claims

1. Apparatus for precisely cutting and polishing gemstones, said apparatus comprising a precision divider (100), a supporting device (200) arranged to be located at a work bench (402) comprising a lap (300) for attachment of grinding and polishing devices, wherein the precision divider (100) is attached pivotal to the supporting device (200), arranged to be pivoted and fixed with its longitudinal axis (124) at a desired angle with the supporting device (200), said precision divider

(100) further comprising a mandrel (101) exhibiting a dopstick recess (106) arranged to accommodate a dopstick (122; 500) carrying a gemstone (400), and means for rotating the precision mandrel (101) about the longitudinal axis (124) and locking the mandrel (101) against rotation during grinding and polishing of the gemstone (400), characterized in that the precision divider (100) comprises a housing (115) accommodating the elongate mandrel

(101) having a first end in which the dopstick recess (106) is formed, and a second end exhibiting a precision graduated disk (120) and a precision dividing gear (118), said mandrel (101), precision dividing gear (118) and graduated disc (120) being arranged rotary in relation to the housing (115) and lockable at a desired rotational position with regard to the longitudinal axis (124) by a mandrel rotation locking device (119, 123), and wherein the supporting device (200) comprises a frame device (210) arranged to be attached to a work bench (402) via a support column (401) in an adjustable manner both in the horizontal plane and in the vertical direction, thus enabling positioning of the frame device (210) and the precision divider (100) at a desired elevation and desired horizontal orientation, said supporting device (200) further including a vertical angle adjustment device comprising a precision divider vertical angle dial (222) and an angle locking device (211, 212, 213, 214), arranged to lock the precision divider (100) in the desired angle position, wherein the supporting device (200) further comprises a fine vertical angle adjustment means (201, 204, 217, 224) arranged to perform fine angle adjustment of the precision divider (100) as a supplement to the vertical angle adjustment device.

2. The apparatus of claim 1, wherein the mandrel (101) is supported rotary within the housing (115) by a first and second bearing (121).

3. The apparatus of claim 1, wherein the fine vertical angle adjustment means comprises a dial (224) having a shaft (204) arranged rotary with respect to the vertical angle dial (222), said shaft (204) exhibiting an eccentric surface (201) serving as a support for a stop pin (109) at the precision divider (100).

4. The apparatus of claim 1, wherein the mandrel rotation locking device comprises a lever (119) arranged pivotal about an adjustment screw (105) at the top of the housing (115), wherein one end of the lever (119) facing the graduated disc (120) exhibits a gear engagement pin (123) arranged to engage with the precision dividing gear (118), pre-tensioned by a spring (108) arranged between the lever (119) and housing (115) to prevent rotation of the mandrel (101) during grinding and polishing.

5. The apparatus of claim 4, wherein the adjustment screw (105) is arranged in a threaded bore in the lever (119) and is provided with a micro balancer dial (116) including a lock screw (107), arranged to perform an accurate re-alignment of the mandrel (101) carrying a dopstick and gemstone from any positional displacements during a transfer from a gemstone crown processing dopstick (122; 500) to a pavilion processing dopstick (122; 500), or vice versa.

6. The apparatus of claim 1, wherein the frame device (210) is provided with a bore (226) and an adjustment lock (223) and lock screw (209), thus providing a releasable attachment of the frame device (210) to the support column (401). 7. The apparatus of claim 1, wherein the dopstick recess (106) in the mandrel (101) exhibits a non- circular cross-section.

8. The apparatus of claim 1, wherein a micrometer depth indicator (227) is attached to the angle locking device (211, 212, 213, 214), accommodated in a recess in the angle locking device (211, 212, 213, 214) with its press-force driven sensor extending down to a shoulder (226) formed in one side of the frame device (210) and abutting the upper surface of the shoulder (226), thus enabling finishing of a gemstone with a precision down to 0.001 millimeter.

Description:
Apparatus for cutting, polishing and processing of gemstones

The present invention is concerning an apparatus for cutting, polishing and processing of gemstones. Background

The invented device includes a platform and a manipulator called precision divider. The present description concerns to manual operation but the invention can accommodate numerically controlled and automatic processing by adopting 3D-step motors.

The current gemstone processing is done manually or with machines that are either very large automatic machines or lack precision and accuracy leading to poor brilliance and dispersion of light. The primitive manual process is called jamb peg where the gemstone is fixed on hand-sticks. In this way, it produces "dead stones" because the asymmetrical facets, irregular sizes and, especially, it misses most crown and pavilion angles. This involves several operators for preforming, cutting to polishing and the working environment is unclean and unhealthy. A faceting machine is described in US 3,559,349 comprising a stationary protractor, an angle setting plate which rotatable on the surface of the protractor about a shaft. A fastening means is provided to fasten the angle setting plate to the protractor at a desired angular position. A faceter spindle is swingable on the surface of the angle setting plate about the shaft while being rotatable about its own axis. However, this machine has several disadvantages. The machine is mounted to a triangular frame 1 provided with three screws 2, 3, 4 which are not anchored to any base. This depends on manual handling and unstable operation resulting in errors during cutting and polishing of a gemstone. Moreover, the screw arrangement mentioned above makes it difficult to control the depth of cutting and polishing. Then, facets will differ from each other in shape and angles. The stationary pointer and angle setting plate 5, 6 are made of relatively thin material which adds to the instability mentioned above. The minimum graduation is 1°, which will make the gemstone to lose reflection, refraction and dispersion of light rays.

US 5,058,324 describes a gem stone face cutting apparatus with a cutting wheel rotating in a horizontal plane and supported above a base which includes a variable speed cutting wheel drive system. The apparatus further comprises angular calibrations, indexing and positional and orientational locking means to place the gem stone at a desired facet angle and orientation. Object

Accordingly, an object of the present invention is to provide an apparatus for finishing gemstones of higher quality in a shorter period of time than has been possible heretofore.

The invention The objects above are achieved by an apparatus in accordance with claim 1. Further advantageous features appear from the dependent claims.

In short terms, the apparatus according to the present invention comprises two main components: a precision divider and a vertical angle and elevation platform. The precision divider is arranged to cut and polish a desired number of facets in a gemstone with high precision. The precision divider is attached, preferably releasable, pivotal to the vertical angle and elevation platform. The precision divider can be positioned and locked in a vertical angle between 0° and 90° to produce precisely cut facets in the gemstone with a desired angle. The precision divider is provided with an improved dopstick receptacle with a non-circular cross-section, and a correspondingly shaped dopstick, thus providing a highly fixed and stable attachment of the gemstone being processed. Long research and development has resulted in this invention, which is a new and precise apparatus for cutting and polishing gemstones. The apparatus according to the present invention is engineered and designed for easy, precise and clean operation by professionals or amateurs. The use of this new machine is easy to learn and even amateurs will accurately and quickly produce "live gemstones". A high quality gemstone can now be cut and polished in a few hours, compared to weeks with manual cutting and polishing.

The apparatus according to the invention is comprised by two major components, a precision divider and an accurate angular platform. These major systems are composed of multiple micro- precise components that allow faceting while cutting and polishing with angular and depth precision of 0.125°, 0.001 mm and 0.10°, which allows even an amateur to quickly, accurately and precisely convert a rough stone into a "lively gemstone" as follows:

• Precise positioning and cutting and polishing

• Accurate repetition of these operations

• Perfect symmetry of facets, triangles and stars

• Obtaining all variety of forms such as oval, marquise, pear, droplet, brilliant

· Clean and safe working bench In further details, the apparatus according to the invention for precisely cutting and polishing of gemstones, comprises a precision divider, a supporting device arranged to be located at a work bench comprising a lap for attachment of grinding and polishing devices, wherein the precision divider is attached pivotal to the supporting device, arranged to be pivoted and fixed with its longitudinal axis at a desired angle with the supporting device, said precision divider further comprising a mandrel exhibiting a dopstick recess arranged to accommodate a dopstick carrying a gemstone, and means for rotating the precision mandrel about the longitudinal axis and locking the mandrel against rotation during grinding and polishing of the gemstone.

According to the invention, the improvement comprises an apparatus of the type described above, wherein the precision divider comprises a housing accommodating the elongate mandrel having a first end in which the dopstick recess is formed, and a second end exhibiting a precision graduated disk and a precision dividing gear, said mandrel, precision dividing gear and graduated disc being arranged rotary in relation to the housing and lockable at a desired rotational position with regard to the longitudinal axis by a mandrel rotation locking device, and wherein the supporting device comprises a frame device arranged to be attached to a work bench via a support column in an adjustable manner both in the horizontal plane and in the vertical direction, thus enabling positioning of the frame device and the precision divider at a desired elevation and desired horizontal orientation, said supporting device further including a vertical angle adjustment device comprising a precision divider vertical angle dial and an angle locking device, arranged to lock the precision divider in the desired angle position, and wherein the supporting device further comprises a fine vertical angle adjustment means arranged to perform fine angle adjustment of the precision divider as a supplement to the vertical angle adjustment device.

The mandrel is advantageously supported rotary within the housing by a first and second bearing, thus providing a proper support for the mandrel and finally the dopstick and gemstone, reducing the risk of cutting wrong angles.

In a preferred embodiment, the fine vertical angle adjustment means comprises a dial having a shaft arranged rotary with respect to the vertical angle dial, said shaft exhibiting an eccentric surface serving as a support for a stop pin at the precision divider. The mandrel rotation locking device preferably comprises a lever arranged pivotal about an adjustment screw at the top of the housing, wherein one end of the lever facing the graduated disc exhibits a gear engagement pin arranged to engage with the precision dividing gear, pre- tensioned by a spring arranged between the lever and housing to prevent rotation of the mandrel during grinding and polishing. This enables a quick setting of facet angle during grinding or polishing. The adjustment screw is advantageously arranged in a threaded bore in the lever and is provided with a micro balancer dial including a lock screw, arranged to perform an accurate re-alignment of the mandrel carrying a dopstick and gemstone from any positional displacements during a transfer from a gemstone crown processing dopstick to a pavilion processing dopstick, or vice versa.

The frame device is preferably provided with a bore and an adjustment lock and lock screw, thus providing a releasable attachment of the frame device to the support column.

In a preferred embodiment, the dopstick recess in the mandrel exhibits a non-circular cross- section. Then, the dopstick exhibits a similar cross-section. In this embodiment, the dopstick and hence the gemstone is prevented from rotation, thus securing a precise cut of the gemstone.

Detailed description The invention is now described in further details by means of drawings, wherein Fig. la is a cross-section through the precision divider in a side view, Fig. lb is a partial cross-section of the precision divider of Fig. 1 in a top-view, Fig. 2a is a partial cross-section of the angular platform in a bottom-view, Fig. 2b is a partial cross-section of the angular platform in a side-vie, Fig. 3a and 3b are perspective illustrations of the apparatus according to the invention, Figs. 4a-4c are drawings illustrating light reflection and refraction from a gemstone, Figs. 4d-4e are drawings of light ray dispersion in a gemstone and air,

Fig. 5 illustrates the precision divider located above a cutting and polishing lap during processing of a gemstone, Figs. 6a-6c are views of side, top and bottom of a brilliant cut gemstone with geometrical proportions for processing, Figs. 7a-7d are two-part drawings of a gemstone in a top view (upper row) and in a side view (lower row) during a process of cutting different facets in the gemstone pavilion,

Figs. 8a-8d are drawings similar to Figs. 7a-7d illustrating cutting of facets in the gemstone crown, and Fig. 9a is a cross-section through a dopstick from the prior art, whereas Fig. 9b is a side view of a dopstick in accordance with the present invention.

Gemstone processing

Initially, the invention is described in general with reference to gemstone faceting and polishing to simplify interpretation of the present invention. Gemstones can be cut and polished in many different shapes. However, for quality purpose, any shape should be cut and polished with symmetric geometry (equal sides, heights) when viewed in horizontal and vertical planes, and the facets should be cut and polished in exact angles to reflect, refract and disperse the incoming and leaving light rays.

The apparatus in accordance with the present invention allows correct cutting and polishing of facets for best quality in terms of brilliance and "fire" or dispersion of light rays. The precise major components of the apparatus according to the invention allow cutting and polishing in precise angles resulting in a gemstone with high optical performance and high quality. The light ray path in this case is shown in Fig. 4a. This drawing illustrates light propagation through a correctly cut gemstone, where light entering at A2 at the left hand side of the stone is reflected back in the same angle at A2" at the right hand side of the gemstone.

However, if the facets are cut and polished in wrong angles, the final stone will have poor optical performance or low quality as shown in Figs. 4b and 4c. Here, the light is not reflected back to an observer viewing the stone from above because the pavilion is cut with wrong face angles. The light ray bounces inside the stone, leaks through the pavilion without returning to the viewer. There will be lack of brightness or scintillation and the stone looks dark and lifeless to the observer. A similar fault will occur if the gemstone crown is cut too shallow. Then, the light will bounce inside the stone and be reflected from the top facet but in a different angle, and the stone will look dark and "lifeless" (not illustrated).

The apparatus according to the present invention allows cutting and polishing of gemstones with maximum desired dispersion, scintillation, "fire" or life. This operation is based on optics where sunlight unfolds to the spectrum of colors between 700 nm (red color) and 300 nm (blue). Notice that the blue ray reflects or bends more than red because the wavelength of blue is shorter than the wavelength of red light. Fig. 4d shows the deflection angle of blue and red colors after crossing prisms. As illustrated in Fig. 4d, blue color (B) bends more from its original path than red color ( ). This invention allows precise set, cut and polish of the facets' angles producing a gemstone that reflects a wider fan of colors ranging from blue to red. This fan colors, emerging from the gemstone's crown, will be perceived by an observer as a rainbow containing the visible spectrum of colors as illustrated in Fig. 4e. The latter figure illustrates light reflection from a perfectly cut gemstone using the present invention by providing a maximum dispersion, scintillation or "fire". Fig. 5 shows the precision divider in the apparatus according to the present invention positioned over a cutting-polishing lap. The precision divider's dopstick 122 holds the gemstone 148 over a lap 300 and allows cutting and polishing facets with 0.1° precise angles for maximum brilliance and distortion of light rays.

A preferred embodiment of the apparatus The invention is now described in further details by a preferred embodiment of the apparatus.

Now referring to Figs, la and lb, a precision divider is illustrated with its multiple components and is indicated in general by reference numeral 100 and having a longitudinal axis indicated at reference numeral 124. The precision divider 100 comprises a mandrel or axle 101 on which the gemstone mounted on a dopstick will be inserted. The mandrel 101 is at its free end (first end) provided with a dopstick recess 106 shaped to accommodate a dopstick on which a gemstone is mounted. The dopstick is lockable in the dopstick recess 106 by one or more lock screws 112. The dopstick is preferably provided with a non-circular cross-section where the recess 106 in the first end of the mandrel 101 is provided with a corresponding cross-section. This improvement makes a more stable and secure fixation of the dopstick, resulting in a more precise cut and alignment of the gemstone. The mandrel 101 is arranged rotary within a housing 115 supported by bearings 121 accommodated within the housing 115. Preferably there are two bearings, one bearing 121 at each end of the housing 115 to provide a more stable support and alignment for the mandrel 101. A precision-graduated disk 120 is attached to the second end of the axle 101 together with a gear

118 arranged to be locked by a gear locking device, here illustrated in the form of a lever 119 attached pivotal at the top of the housing 115, pivotal between a locked position where the lever

119 is in engagement with the teeth of the gear 118 by a lever engagement pin 123 at the end of the lever 119 facing the gear 118, and an unlocked position where the lever 119 is elevated out of engagement with the gear 118 to allow rotation of the mandrel 101 to a desired angular position indicated on the graduated disk 120. The lever 119 is pre-tensioned by a gear lever spring 108, resting in an engagement with the teeth on gear 118. The number of indicators on the graduated disk 120 corresponds to the number of teeth on the gear 118 and hence the desired maximum number of facets in the gemstone to be prepared and processed.

A micro balancer is arranged at the housing 115 to allow fine-adjustment of the angle position of the mandrel 101 about it rotational axis with a precision of 0.125°. The micro balancer comprises a micro balancer dial 116 attached to an adjustment screw 105 accommodated in the housing 115 extending through the lever 119. The lever 119 is attached pivotal to the housing 115 about the screw 105, movable in a direction substantially perpendicular to the longitudinal axis of the mandrel 101 by operating the dial 116. The dial 116 is provided with a lock screw 107 to enable the dial 116 to be locked in a fixed position. The dial 116 is provided with grades (Fig. 3a). When the lever 119 is in an interlocked engagement with the gear 118, the position (angle of rotation) of the mandrel 101 can be fine-adjusted by operating the dial 116 to push or pull the lever 119 in a direction substantially perpendicular to the longitudinal axis of the mandrel 101. The purpose of this fine-adjustment is to compensate for any gemstone displacement between transfer from crown processing to pavilion processing, or vice versa. This fine-adjustment is only performed once before processing the first facet of the gemstone after a transfer.

Now also referring to Figs. 2a and 2b, the precision divider 100 is supported by an angular platform indicated generally by reference numeral 200 exhibiting a frame device or bracket 210 supporting numerous components as described in further detail below. The precision divider 100 is arranged pivotal about a first and second pin 205 and 205', between 0 and 90° with respect to the horizontal level. The pins 205 and 205' are arranged in the sidewalls of an opening provided in the bracket 210. The angular platform 200 is used to set the gemstone cutting or polishing angle. A lock screw 221 is provided to enable the precision divider 100 to be fixed in a desired vertical angular position. Locking screws 219 are provided in threaded ports in the bracket 210, arranged to prevent slackening of the pivotal attachment of the precision divider 100 to the pins 205 and 205'. The angular platform 200 including the attached precision divider 100 can be fixed at a desired elevation by an adjustment lock 223 to a supporting column 401 (Fig. 3a) extending vertically from a work bench 402 (Figs. 3a and 3b) supporting a lap or turntable (reference numeral 300 in Fig. 5) with a rotary grinding surface to process the gemstone in question. The support column, workbench and turntable are considered to be prior art and is not discussed in further detail here. In this manner, the angular platform 200 can be rotated horizontally to be fixed in any position in the xy-plane, and has a desired total vertical displacement, e.g. 50 cm, and is able to reach any position in the z-axis with a precision of 1 micrometer. Accordingly, it can be locked in a specific vertical position while allowing full horizontal rotation and vertical movement with micrometric adjustment and with high precision.

The angular platform further comprises a vertical bore 226 arranged to accommodate the platform supporting column mentioned above, allowing vertical adjustment of the angular platform 200 and attachment at a desired elevation. A precision divider elevation angle dial 222 is attached rotary to the platform 200 by an axle 227 and is connected to a supporting pin 205, which centrally holds the precision divider 100 while allowing full rotation supported. The elevation angle dial 222 is provided in the form of a partial circle shaped disc and is provided with grades on the surface indicating angles from 0 to 90°. The rim of the disc is provided with teeth 225 corresponding to the number of grades on its surface. A locking and balancing device 211 is attached to the platform 200, serving as link and lock for the precision divider 100 at a desired angle in the vertical direction. The locking device 211 is attached pivotal about an axle 208 and exhibits a guide-link 212 located at the end of the locking device 211 that faces the teeth 225 of the angle dial 222. The guide link 212 is arranged to engage with the teeth 225 on the angle dial 222 to lock the precision divider 100 in the desired vertical angle position. The guide link 212 is arranged slideably in the locking device 211, supported in a recess in the locking device 211 and pre-tensioned by a spring 214 which forces the guide link 212 towards the teeth 225 of the angle dial 222. A locking screw 213 is arranged in an elongate recess in the locking device 211 and connected to the guide link 212. The locking screw 213 can be operated to move the guide link 212 out of engagement with the toothed 225 precision divider elevation angle dial 222. A spring 206 is arranged in a space between the locking device 211 and the upper surface of a shoulder 226 formed in the side of the angular platform 200.

Moreover, the angle dial 222 is provided with a fine-angle adjustment dial 224 arranged rotary within the angle dial 222 by a shaft 204. The end of the shaft 204 is provided with an eccentric surface 201 which serves as an adjustable stop means for the precision divider 100. When a stop pin 109 attached to the precision divider abuts the eccentric surface 201, the angle of the precision divider can be adjusted with a precision down to 0.1°.

A micrometer depth indicator 227 (Fig. 3a and 3b) is attached to the locking device 211. The depth indicator 227 is a commercially available mechanical depth indicator having a display and a press- force driven sensor. The depth indicator 227 is accommodated in a recess in the locking device 211 with its press-force driven sensor extending down to a shoulder 226 formed in one side of the angular platform 200 and abutting the upper surface of the shoulder 226. The micrometer depth indicator 227 enables finishing of a gemstone with a precision down to 0.001 millimeter.

The precision divider movement describes a global and spherical shell and can be positioned at any angle between 0 to 360° with the vertical z-axis with accuracy of 0.1°. It has a micrometer depth indicator and is able displace up and down the z-axis with a precision of 1 micrometer. Accordingly, it has and accuracy of 0.001 millimeter for precisely cut and polished gemstones while the gemstone's pavilion and crown facets angle can be set in the required angle in the range of 0 to 90° with the vertical z-axis, as desired for brilliance and dispersion of light rays. The precision divider 100 containing a precision dividing gear 118, a gear engaging lever 119 and a precision-graduated disk 120, allows setting of precise division indexes or circle intervals, where the number of circle intervals corresponds to the desired number of facets around the circumference of the gemstone. The apparatus according to the present invention can cut and polish any complex form or design of gemstones with varying hardness and refraction index, such as sapphire or ruby, topaz, aquamarine, emerald, amethyst, etc. The apparatus is also able to accurately cut and polish different shapes including round brilliant and other rounds, cut-corner rectangular emerald, oval, marquise, navette, heart, pear, etc. Examples of gemstone shapes can be found in the literature and is not illustrated in further detail here.

Figs. 3a and 3b are perspective illustrations of the apparatus according to the present invention in an elevational side view and top view, respectively. These illustrations show a prototype of the apparatus in an assembled condition, comprising the precision divider 100 attached pivotal to the angular platform attached to a support column extending upward from a work bench 402.

Figs. 9a is a cross-section through a dopstick 500 from the prior art, comprising a (circular) connector pin 501 and a gemstone socket 502 holding a gemstone indicated at reference numeral 400. A improved dopstick according to the present invention is illustrated in a side view in Fig. 9b, where a recess 503 has been cut in the connector pin 501. The dopstick recess 106 (Fig. la) is provided with a corresponding cross-section. In this way, the gemstone will be connected in a fixed position prevented from any rotation.

In the following, gemstone processing using the apparatus in accordance with the present invention is described in form of an example and accompanied by illustrations in Figs. 5-8. Cutting and polishing steps

As a demonstration, we now set the device's components to cut and polish a round brilliant gemstone based on the following data:

In the example, the precision divider according to the invention is provided with a precision dividing gear 118 having 96 indexes, distributed evenly around the circular 360° rim of the gear 118. However, 96 index positions is only an example and an increased or decreased number could be provided as well. As mentioned above, the number of facets cut in a gemstone corresponds to the number of gear 118 indexes or a division thereof.

The task is to produce a gemstone having a round brilliant cut with 73 facets and a refraction index of 1.526. Its proportions are shown in Fig. 6a-6c. The number of facets in the pavilion and the crown including required angles are given in Table 1 (pavilion) and Table 2 (crown).

Fig. 6a is a bottom view of the gemstone, showing the pavilion facets according to requirements in Table 1. Here we can se a number of 8 facets, so-called "mains" and indicated at number 3 in the drawing. A number of 16 facets, so-called "breaks" are indicated at number 1 in the drawing. Finally, a number of 16 facets, so-called "girdles" are indicated at number 2 in the drawing. The number of breaks always corresponds to the number of girdles, in this case 16.

Fig. 6b is a side view of the gemstone showing the proportions between the crown and pavilion.

Fig. 6c is a top view of crown of the targeted gemstone according to Table 2. It shows the number of facets and the proportions between the so-called "table" (indicated at number 4) and the maximum width of the gemstone. A number of 8 facets, so-called "stars" are indicated at number 3. A number of 8 facets or mains are indicated at number 2 in the drawings, whereas a number of 16 facets or "breaks" are indicated at number 1.

The successive steps of the facet cutting process of the gemstone is illustrated in Figs. 7a-7d and 8a-8d. A gemstone (reference numeral 148 in Fig. 5) is mounted in the dopstick with its crown seated and affixed with glue in the dopstick gemstone receptacle. Then, the vertical angle of the precision divider 100 holding the gemstone 148 to be processed is adjusted by the geared angle dial 222 (Figs. 2b and 3). Then, the lever 119 is released and the gear 118 is moved to position # 12 on the graduated disk 120, whereupon the lever 119 is brought back to an interlocking engagement with the gear 118. This step is indicated in step PI in Table 1, where the rightmost column shows the index positions involved and their sequence of processing. Then the gemstone is brought into contact with the (rotating) lap (reference numeral 300 in Fig. 5) and the facet is cut and polished to a desired depth, indicated by the depth indicator.

In the next step, the lever 119 of the precision divider 100 is released and the graduated disk 120 (including the attached gemstone and gear 118) is rotated to index position 24 on the graduated disk 120 and locked again, whereupon the second mains facet is cut in the gemstone (see step PI in Table 1 and the gear index position 24 on the graduated disk 120 shown in the rightmost column in the tables).

The PI steps above are repeated for gear index position 36, 48, 60, 72, 84 and 96 on the graduated disk 120 to provide a pavilion having a total of 8 mains facets. This stage is illustrated in Fig. 7a, where the upper figure is a top view of the pavilion and the lower part is a side view of the pavilion with the mains facets indicated at number 1. Accordingly, the figures 7a-7d illustrate the same number of facets for round brilliant, as set forth in the tables, but the principle is the same for another shape of a gemstone having a pavilion with different number of facets. Then, the operator moves on to step P2 where the angle of the precision divider 100 holding the gemstone 148 to be processed is adjusted to 90° as described above, whereupon the position of the graduated disc 120 is moved to index position 3. Then the gemstone 148 is brought into contact with the (rotating) lap 300 and the facet is cut as described above. Then the graduated disc 120 is rotated to the respective index position set forth in column "Gear index on disk 120" in Table 1 step P2 to produce a total of 16 girdles in step P2. The result is indicated in Fig. 7b, though with a different number of facets as mentioned above.

The breaks and transfers of the pavilion are cut in a similar manner with angle and gear index positions as set forth in the steps P3 and P4 in Table 1. The results of the respective steps are illustrated accordingly in Figs. 7c and 7d for the respective steps. The pavilion of the gemstone has now been completely cut and the next step is to perform similar cuts in the crown. The gemstone 148 is, in a manner known per se, removed from the dopstick 122 (Fig. 5) by heating the glue, and is transferred to another dopstick 122 and fixed with glue in a similar manner, exposing the raw crown of the gemstone 148.

The facet cutting process proceeds in a similar manner as described above, starting with the mains and then proceeding with the breaks, the stars and finally the table from steps CI through C4 with the angles and gear index positions as indicated in table 2. The emerging facet patterns are illustrated in Fig. 8a (mains), Fig. 8b (breaks), Fig. 8c (stars) and Fig. 8d (table), which are drawings similar to the pavilion drawings in Fig. 7a-d. Also here, the number of facets illustrated in the drawings is the same as the respective number set forth in table 2.

Table 1.

Gear index to cut and polish the pavilion facets of a round brilliant

Table 2.

Gear index to cut and polish the crown facets of a round brilliant

When the facet cutting procedure has been completed, the grinding lap is exchanged by a polishing lap or the precision divider 100 is turned to a separate polishing lap and the same steps as described above for the facet cutting is repeated, to provide a precisely cut and polished gemstone with perfect angles. While the apparatus according to the invention has been described as a manually operated apparatus, the invention is not limited to this. The apparatus can be automated as well.

Reference numerals

100 precision divider

101 mandrel or axle

102 guide bushing

103 knob-lock of the mandrel and divider-gear

104 manipulator's balancer axle

105 balancer adjusting screw

106 dopstick recess/lock housing

107 lock screw

108 lever-gear spring

109 platform/precision stop pin

110 balancer positioning nut

111 mandrel's wooden protection and decoration

112 dopstick locking-screw

113 adjusting lock-knob screw

114 screw for the guide-bushing

115 housing (mandrel-lever-gear box)

116 micro balancer dial

117 washer

118 precision-dividing gear

119 gear-engaging lever

120 precision-graduated disk

121 ball bearings

122 dopstick

123 gear engagement pin

124 longitudinal axis of precision divider

200 angular platform

201 eccentric axle-support surface

202 dynamic support for the depth indicator

203 platform axle

204 shaft for the fine-angle adjustment dial and eccentric surface

205 shaft for coupling the platform and manipulator

206 spring

207 left stop screw 208 locking device axle screw

209 platform lock screw

210 bracket/frame device

211 locking device and support for depth indicator 212 guide-link

213 locking screw

214 spring

215 locking device stop screw

216 screw

217 screw

218 washer

219 locking screw for platform and precision divider

220 locking screw for angle set dial

221 platform screw axle

222 precision divider vertical angle dial

223 platform vertical adjustment lock

224 fine angle adjustment dial

225 vertical angle dial teeth

226 vertical bore

227 depth indicator

226 platform shoulder

300 lap/turntable

400 gemstone

401 support column

402 work bench

500 dopstick

501 dopstick connector pin

502 dopstick gemstone socket

503 dopstick connector pin recess




 
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