HK1051721B - Systems, apparatuses and methods for diamond color measurement and analysis - Google Patents

Description

Diamond color measurement and analysis system, apparatus and method

Technical Field

The present invention relates to systems, devices and methods for gemstone color measurement and analysis, and more particularly to systems, devices and methods for measuring and analyzing the color of a diamond in a manner that approximates visual measurement and analysis methods.

Background

Diamonds or other gemstones are often analyzed for their visual appearance to the human eye. Indeed, the visual appearance of a diamond to the human eye under natural or near daylight is a major indicator of the quality of a diamond. Thus, because diamond quality is essentially based on human vision, diamond analysis requires judgment of experience, evaluation of information, and differentiation of nuances based on visual comparisons.

In practice, the diamond quality analysis is preferably performed by a trained group of people who visually inspect the diamond for characteristics such as inclusions and structural defects. This intensive process involves a number of detections, measurements and examinations by each person. The process also includes quality control and may include various non-destructive tests to identify processes, fillers, or other defects that may affect sample quality. Finally, the process involves a detailed visual comparison of the diamond with a set of diamond master stone reference standards that serve as historical standards for diamond color and clarity.

The diamond analysis basis comprises the four C analysis (color, clarity, cut and carat weight), which is the analysis method invented by the american gem association (GIA). Two of the four C, color and clarity, were evaluated in terms of grade or continuum. In the case of colorless to yellow colored diamonds, the analysis is performed according to a scale, commonly referred to as the GIA D-Z scale. The GIA D-Z color scale, which changes from colorless to yellow, is an international standard that has been calibrated to the GIA standard diamond due to its development.

As mentioned above, the visual inspection process of diamond analysis is delicate, time consuming and requires specially trained and experienced individuals. Thus, many people in the jewelry and gemstone arts claim an instrument that can closely analyze the color of a diamond according to the D to Z criteria. Over the years, a number of mechanical instruments have been proposed to "measure" the color of delicate diamonds. However, these instruments do not achieve the required level of accuracy and reproducibility due to various deficiencies, in addition to the problems of correcting errors and electronic drift. Moreover, these instruments do not approximate visual color analysis methods in a way that can make their meaningful results within the scope of historical analysis criteria.

The history of mechanical gemstone color grading instruments dates back at least to the 40 th 20 th century, when the founder of the GIA, dr. The Shipley device places a colored wedge (wedge) behind a static diamond base plate, allowing the user to compare the color of the diamond to the background of the colored wedge. The Shipley device then serves as a visual inspection aid by relying on the human eye and brain rather than on mechanical photodetectors and optical measuring devices and processors.

In the 50 s of the 20 th century, dr, shipley invented a first non-vision gemstone color analyzer, an improved color comparator comprising a tungsten lamp as the light source, a photocell as the light detector, blue and yellow filters, a static gemstone holder, and an iris light control device that conducted light to the photocell. According to the method of the Shipley colorimeter (Colormeter), the instrument user places the diamond table face down over the diffuser plate, whereby the tungsten light is first conducted through the diamond and then through the iris light control device to the photocell. The instrument user then performs sequential light transmission measurements, first deploying a blue filter and then a yellow filter. According to the method of the invention, the instrument user sequentially compares the two conductivity levels detected by the photocells and looks up the results in a table arranged from D to Z gradations to determine the color index of the diamond.

Although the Shipley colorimeter has provided a color standard for many years, the standard is not precisely correlated with historical visual analysis standards for a variety of reasons. First, the geometry between the diamond, light source and detector is not close to that of visual diamond analysis. Second, tungsten lamps, while fairly stable in output, do not provide daylight conditions that are already standard for visual analysis of diamonds or other gemstones. Third, the photocell detector cannot record every frequency in the visible light spectrum, like the human eye, but tracks changes in the overall spectral content due to changes in the filter. Thus, while the Shipley colorimeter method provides a very useful and innovative instrument for non-visual diamond color analysis, it does not provide accurate access to the visual analysis method. Furthermore, during analysis, the diamond is static rather than rotating, and therefore the device cannot average the colour over the entire 360 °.

In the 70's of the 20 th century, two new types of color measuring instruments were introduced by the Eickhorst colorimeter and the Okuda colorimeter. While still based on the method of the Shipley colorimeter color comparator, Eickhorst discloses the concept of using fiber optic couplers to direct light to photodetectors. Okuda discloses the concept of a voltage stabilized tungsten lamp source and integrating sphere to direct light onto the diamond. However, like the Shipley colorimeter, these instruments rely on tungsten filament lamps as their light source. Also, like the Shipley colorimeter, these devices compare the total amount of light transmitted by the diamond in response to the use of two different frequency filters. Furthermore the Eickhorst and Okuda instruments introduce tungsten light into the crown facets of the diamond, rather than illuminating the diamond into its pavilion sides, and then do not measure the light emanating from the pavilion sides, as is required in visual diamond analysis.

In the 80's of the 20 th century, U.S. patent US4508449 to Okazaki, disclosed a device for measuring the color of a polished engraved diamond by measuring light from a defined spectrum of the diamond using a spectrophotometer. The instrument includes an arithmetic unit for deriving tristimulus values X, Y and Z from the measured spectrum. Okazaki also discloses the use of a xenon or halogen white light source and filters (monochromators) to provide a beam of monochromatic light that sequentially changes frequency over the spectral band of interest. Okazaki also discloses a method of recording the magnitude of light emitted from a diamond in response to sequential changes in frequency within a spectral band of interest. Okazaki teaches not to visually introduce light into the side of a diamond pavilion (col.1, 11.38-39) and neither directly nor indirectly detects a specific angle of light from the diamond. In addition, Okazaki uses a photomultiplier tube and sequential measurements of the frequency response in the spectral band of interest create unwanted time delays in recording the transmission spectrum.

Some improvements have been seen in diamond colour analyzers in the 90 s of the 20 th century. For example, Austron colorimeters and Gran colorimeters disclose the use of photodiodes as photodetectors. Like their predecessors, Austron and Gran colorimeters used halogen and tungsten lamps, respectively, and their light was directed into the top of the diamond. These instruments also do not rotate the diamond during the measurement. In addition, these instruments rely on colorimeter comparisons of sequential filters and, in the case of a Gran colorimeter, compile tristimulus color values.

Other instruments use spectrophotometers to improve the inertia and accuracy of gemstone color analysis. For example, Zeiss-Gubelin disclosed an instrument that used a spectrophotometer in 1992. The Zeiss-Gubelin system conducts light from a xenon flash lamp into the pavilion facet of the diamond via a integrating sphere, with the table placed down and using the same integrating sphere to indirectly detect the light code emitted from all angles of the diamond pavilion facet. The Zeiss-Gubelin system also used a xenon flash lamp for static measurement of diamonds.

Subsequent spectrophotometer systems, including rennlson-Hale gemstone colorimeters, Lamdaspec spectrophotometers, and Gran spectrophotometers (DC2000FS), used tungsten, halogen, and/or xenon lamps. While these systems are capable of detecting and analyzing the full spectrum of light, these instruments themselves cannot take into account the geometrical relationships of visual diamond analysis. Moreover, none of these systems use dynamic color analysis techniques involving diamond rotation. And these systems do not average the color of the diamond over the entire 360 range.

An Adamas system was developed that performs color analysis and configures a spectrophotometer. However, the Adams system illuminates through the diamond table, using an integrating sphere and analyzing the color using a single static measurement. Such instruments also do not provide access to visual color analysis methods and do not meaningfully correlate results with historical precedent of visual diamond analysis.

There is therefore a need for a simple system and instrument that reliably and consistently approaches historical visual analysis methods, including, for example, the detection methods, light source composition, illumination angles, and the use of historical visual analysis criteria, in order to correlate instrument results and historical precedent. There is also a need for systems and instruments that approximate the steady output of daylight, which can compensate for electronic drift, and which can reduce the disturbing effects of light scattering and direct reflection that occur in mechanical analog vision detection methods. Existing devices are inadequate for these purposes.

Disclosure of Invention

The present invention comprises a system, apparatus (instrument) and method for analyzing the color of a gemstone in a manner that reliably and consistently simulates a visual color analysis method. Preferred embodiments of the present invention consist of a number of aspects including the use of near daylight lamps, such as near daylight fluorescent tubes, and the use of geometries that simulate the results of visual analysis. In the case of non-quality color diamond analysis, in one embodiment, the system includes three main components: a daylight-approximating light source illuminating the sides of the diamond pavilion; a light detector for detecting light emitted from the side of the diamond pavilion at a specific angle; and an optical measuring device that measures the light detected by the photodetector. In another embodiment, a measurement chamber surrounds the diamond to be analyzed and a daylight-approximating light source illuminates the diamond pavilion sides through a diffuser (diffuser). Although a variety of photodetectors and optical measuring devices may be used in the present invention, in a preferred embodiment, the photodetector comprises a fiber optic cable connected to a diode array and the optical measuring device comprises a spectrophotometer. In another preferred embodiment of the present invention, the system further comprises a fourth element: an optical analysis device, for example a data processor, compares the measured data obtained from the optical measuring device with historical precedent and/or converts these data into the CIE chromaticity space.

According to one embodiment of the invention, the system comprises four elements: a daylight-approximating light source illuminating the sides of the diamond pavilion; a rotator for rotating the diamond during illumination; a light detector and an optical measuring device which measures the light detected by the light detector. In a preferred refinement of this embodiment, the optical measuring device measures the light that the detector has detected, which light emanates from the diamond at a particular angle relative to the table of the diamond during a single rotation of the diamond.

The various elements of the invention disclosed herein may be provided as separate pieces or as a single unit. For example, in the foregoing embodiments, the light source and the rotor may form part of an integral unit, or alternatively, be provided separately. In another embodiment, the light detector and the optical measuring device may comprise an integral unit having a light source and a rotor. The integral unit may also contain an optical analysis device. Also, in the case of a diode array spectrophotometer, the elements of the photodetector may be part of the same unit as the optical measurement device, or may be provided separately.

To overcome the difficulties associated with visual analysis of geometry, the preferred embodiment of the present invention includes at least one of several innovations to increase the stability and reliability of the system. In a preferred embodiment, to stabilize a near-daylight light source, the system includes a high frequency ballast. Also, in another preferred embodiment, the system includes a light diffuser (diffuser) positioned between the light source and the gemstone to reduce the disturbing effects of dispersion (dispersion) and direct reflection due to the type of illumination used in visual color analysis. In another preferred embodiment, the invention includes a mechanism to process a plurality of individual spectral measurements during rotation of the gemstone. According to this preferred embodiment, the present invention comprises a rotating platform optionally having a stabilizing ring to ensure its rotation in unison. In another embodiment, designed to overcome the difficulties associated with electronic drift, the present invention includes a drift correction component that can operate statically or dynamically.

The method of the present invention generally involves analyzing gemstone color based on historical precedent using a system and apparatus. According to one aspect of the method, the method of the invention comprises the steps of: illuminating the gemstone with a proximity daylight lamp, detecting light emanating from the gemstone at a particular angle, measuring the detected light with an optical measuring device, analyzing the measured data with an optical analyzing device and expressing the gemstone's color according to historical precedent.

According to another aspect of the method of the invention which may be particularly useful for diamond analysis, the method comprises the steps of: the method comprises the steps of illuminating the side of the diamond pavilion with a proximity fluorescent lamp, detecting light emitted from the side of the pavilion at a specific angle with respect to the table of the diamond, facing downward from the table, measuring the detected light with an optical measuring device and comparing the measured data with historical precedent. According to another aspect of the method of the invention, the method comprises the steps of: placing the diamond on a rotating platform, illuminating the side of the diamond pavilion with a near fluorescent lamp, rotating the rotating platform, detecting light emitted from the side of the diamond pavilion at a specific angle relative to the table surface of the diamond during the rotation, and measuring the detected light and analyzing the measured data with an optical measuring device.

With respect to the system and apparatus, it is an object of the present invention to increase the ease with which individuals can substantially obtain a reliable analysis of the color of a gemstone. It is another object of the present invention to overcome the difficulties associated with the application of visual analysis geometry to mechanical analysis systems. It is another object of the present invention to provide a stable and reliable system for gemstone color analysis. It is another object of the present invention to reduce chromatic dispersion and direct reflection during gemstone color analysis.

With respect to the method of the invention, it is an object of the invention to provide a color analysis method that can be performed by individuals with little technical training or experience in the gemstone. It is yet another object of the present invention to provide a method that allows individuals with little technical training or experience in gemstones to reliably and consistently obtain semi-automated color analysis according to visual color analysis methods.

Brief description of the drawings

Reference is made to the accompanying brief description of the drawings which is intended to illustrate the gemstone color analysis system and apparatus used as disclosed herein. The drawings and the following detailed description are illustrative only and are not intended to limit the scope of the invention as set forth in the claims.

Fig. 1 depicts a light box that is overhead illuminated by near-daylight fluorescent lamps (high frequency ballast not shown).

Figure 2 shows a perspective angled view of a photosensitive fiber optic cable according to a simple embodiment of the invention, the cable being directed at an angle between 0 and about 45 degrees relative to the table of a diamond with the table facing downward when the diamond is provided on a rotating platform. The rotating platform and diffuser are shown in the light box of fig. 1.

Figure 3 shows a perspective angled view of a simple embodiment of the invention where a diamond with its table facing down is placed on a rotating platform, where the rotating platform is enclosed by a measuring chamber. The diffuser separates the light source (not shown) and the diamond.

Fig. 4 shows the embodiment of fig. 3 without the measurement chamber and diffuser.

FIG. 5 shows a perspective angled view of a preferred integral unit embodiment of the present invention in which a fiber optic cable is housed in the light sensor housing and disposed above the rotating platform at an angle between 0 and about 45 degrees.

Fig. 6 shows the embodiment of fig. 5 with the measurement chamber in a fully deployed position.

FIG. 7 shows a perspective angular view of another embodiment of the present invention, wherein the present invention incorporates a swing arm with a dark reference that enables dark reading (dark reading) as part of the calibration step.

Fig. 8 shows a top perspective view of the alternative embodiment of fig. 7, where the swing arm is in a nearly closed position.

Figure 9 shows a combination of an embodiment of the invention with a drift correction component comprising a second fiber optic cable leading into the standard material measurement chamber and the reference platform at an angle between 0 and about 45 degrees, made of the same material and having the same diffuser as the measurement chamber and the rotating platform.

Fig. 10 shows a complete view of the system of the invention, including the light box, the meter, the light measuring device, the data processor and the monitor.

FIG. 11 shows a perspective angled view of another embodiment of the invention in which the meter is an integrated unit and the position of the light detector relative to the platform (not shown) is adjusted by a positioning member.

Figure 12 shows the gauge of figure 11 placed in a light box ready for use.

Detailed Description

FIG. 1 shows one embodiment of portions of the system of the present invention, as disclosed and used herein. In this embodiment, the system comprises at least one near daylight lamp 10 providing a light source similar to that used in diamond visual color analysis. According to this embodiment, a light source is provided in the light box 20 and provides top illumination to the gemstone (not shown) contained within the light box. The light box of fig. 1 may be of any size capable of holding a light source and a diamond or other gemstone. In the embodiment shown in fig. 1, the daylight approximating lamp is a daylight approximating fluorescent lamp for visual color analysis, which may be, for example, Osram Biolux 72, Verilux F20T12, or Gretag Macheth F20T 1265. However, other lamps having a color temperature between 5500 and 6500K, having a high color rendering index (rendering index), preferably at least 95, may also be used. The light box has a length similar to that of a preferred daylight-approximating fluorescent lamp. The interior 22 of the light box 20 preferably has white or light gray walls.

According to another aspect of the invention, the system forms a novel illumination by: improved halogen light sources having a high color temperature, preferably above 4000K (absolute), and improved filters which increase the color temperature to be equivalent to daylight, preferably between 5500 and 6500K. According to this aspect of the invention, the illumination source may comprise a halogen lamp, preferably using a stabilized power supply, boosted to approximate daylight conditions by a daylight correction filter, such as a Schott filter BG26/2 mm.

Figure 2 shows a simple embodiment of the gauge of the invention together with the light source and light box of figure 1. According to a simple embodiment of the gauge, a light detector 30 comprising a fiber optic cable is directed at an angle between 0 and about 45 degrees to the pavilion facet of the diamond 40, which pavilion facet is set on a rotating platform 50. The rotating platform 50 is in turn connected to a rotor 70 via a stabilizer cylinder 60. In fig. 2 is shown a rotating platform 50 located within the light box 20, light propagating from the lamp 10 through a diffuser 90 in the direction of the pavilion facet of the diamond 40. This form of diffuse transmission serves to reduce the blocking effects of direct light reflection and dispersion and substantially facilitates the detection of specific angles of light emitted from the diamond, which approximates visual analysis methods.

According to one embodiment, diffuser 90 is made of thin Polytetrafluoroethylene (PTFE), but other suitable equivalent diffusing materials may be used. In a preferred embodiment, the diffuser has a thickness of between 0.06mm and 1.0mmMade, and in the most preferred embodiment 0.4mm thickAnd (5) manufacturing. The rotor 70 preferably comprises a continuous load motor, such as a 3W synchronous ac continuous load motor. In the most preferred embodiment, the rotor 70 rotates at 20rpm, although many rotational speeds may be used, which are coordinated with the measurement and analysis components of the system. As shown in fig. 2, the light detector comprising the fiber optic cable 30 further comprises a collimator 100. However, while the light detector preferably comprises a fiber optic cable 30 and a collimator 100, other light detectors suitable for approximate visual analysis methods may be used. As shown in fig. 2, the cross-section of the rotating platform 50 is preferably circular for stability. However, other platform shapes may be used. Also, although FIG. 2 shows the rotor 70 and the photodetector comprising the fiber optic cable 30 physically disconnected, they may form an integral meter portion (see FIG. 5).

Figure 3 shows a perspective angled view of an embodiment of the gauge of the invention in which a diamond 40 rests on the surface of a rotating platform 50 in a table-down position. In fig. 3, the rotary platform 50 is rotatably coupled to the rotor 70. Rotating platform50 is also enclosed by the measurement chamber 110 and a diffuser 130, preferably located between the light source (not shown) and the diamond and close to the diamond 40. In the embodiment shown in FIG. 2, diffuser 130 is preferably a thin white colorMade of a material that diffuses light propagating from the crown facets of the diamond. According to a preferred embodiment, the measurement chamber 110 and the rotating platform 50 are made of a reflective material, more preferably a diffuse, reflective material, and most preferably a diffuse, white reflective material such as tetrafluoroethylene (PTFE). Other materials such as barium sulfate orThey have the lowest absorbance in the visible and near Ultraviolet (UV) spectrum. In a preferred embodiment, the material also does not fluoresce to ultraviolet radiation. In the embodiment shown in fig. 3, the diffuser 130 is connected to the top of the measurement chamber 110, whereby it at least partially seals the top of the measurement chamber. As shown in fig. 3, the measuring chamber is preferably a cylinder with a circular cross-section. Alternatively, the measurement chamber may have other cross-sectional shapes. According to the embodiment of fig. 3, a light source (not shown) illuminates the diamond 40 from the pavilion side while the rotating platform 50 rotates, and a light detector comprising a fiber optic cable 30 detects light emitted at a specific angle from the rotating diamond pavilion side.

Fig. 4 shows the embodiment of fig. 3 with the measurement chamber 110 and diffuser 130 removed. The geometrical relationship between the diamond 40, the rotating platform 50 and the light detector containing the fiber optic cable 30 approximates the geometry of the visual color analysis method. The rotatable platform 50 is optionally stabilized by a circular stationary cylinder 60 which is stably attached to the bottom of the rotatable shaft 55 of the rotatable platform 50. The rotatable platform 50 preferably has a slightly concave top so that it can more reliably receive a diamond with the table facing downwards. Preferably, the rotatable platform 50 has a slope of about 3 degrees from its centre to each point on its circumference to stabilise the diamond during rotation. The stabilizing cylinder 60 may be of various heights and may even extend across the horizontal plane of the rotating platform 50. The stabilizer cylinder may also support the measurement chamber 110 when the measurement chamber is used. Although the surface that receives the diamond is shown as a platform, other types of surfaces, such as the bottom of the instrument itself, may be used to receive the diamond.

In a preferred embodiment, the platform doubles as a white reference for calibration purposes. According to this embodiment, the user takes calibration readings based on the detection of light from the platform after the gemstone has been removed. The user can then recalibrate the measuring device, for example by pressing a button on the spectrophotometer, the reading should be changed between gemstone analyses. Alternatively, the calibration readings and/or recalibration of the instrument may occur automatically between gemstone analyses.

In a preferred embodiment of the meter section of the present invention, as shown in FIG. 5, the fiber optic cable 30, the rotator 70, the rotating platform 50 and the measurement chamber 110 are all integrated on the base 140. Thus, the rotor, the rotating platform and the light detector are part of an integral unit that maintains the proper geometric relationships consistent with visual color analysis methods. As shown in fig. 5, the rotatable platform 50 may be formed as a unit having a cylindrical body 150 that stabilizes the rotation of the rotatable platform. The fiber optic cable 30 (not shown) is preferably contained in the light detector housing 160 whereby the detection end of the diamond cable is positioned at an angle between 0 and about 45 degrees at which a table will rest on the rotating platform 50. The light detector housing 160 may have a collimator (not shown) and a light pipe 170 to ensure that the light correction angle from the gemstone is detected. The optional angle adjustment mechanism 180 may be changed to change the light detection angle by the light detector. In the embodiment shown in fig. 5, the angle adjustment mechanism 180 comprises a plurality of slotted frames 190a and 190 b. The angle adjustment mechanism is optionally connected to an angular direction reader (not shown), which may be analog (as shown in fig. 9) or digital. In another embodiment, the light detector may be rotated around a fixed diamond receiving surface to detect light emitted from the diamond.

According to a preferred embodiment of the invention, the light detector detects light coming directly from the diamond at a specific angle relative to the table of the diamond. In the case of non-quality colored diamonds, the particular angle at which light is detected is preferably between 0 and about 45 degrees relative to the table of the diamond with the table facing downward. Although other detection angles may be used, such angles are not preferred to the extent that they are close to the visual analysis method. However, according to a preferred embodiment, the detector may detect light emanating from the side of the non-fancy-coloured diamond pavilion at more than one angle, sequentially or simultaneously, but within a certain range of angles, preferably between 0 and about 45 degrees relative to the table of the diamond with the table facing downwards. Detection of multiple angles within a particular range may be achieved by various techniques according to this embodiment, including moving the detector during detection, using additional detectors, using a wide angle detector, and/or tilting the platform or other gemstone receiving surface during rotation. For a rotating gemstone, if the detection of multiple angles within a particular range occurs sequentially, then the change in angle after full rotation occurs better. In the case of simultaneous detection, for non-fancy colored diamonds, the detector or detectors better detect multiple angles within a particular range during a single rotation.

According to this preferred embodiment, the light detector detects light emitted from the diamond at a particular angle at a distance identifiable with respect to the centre of the diamond with the table facing downwards. For non-fancy colored diamonds, the distance is preferably between 10mm and 50mm from the center of the diamond with the table side down. If a collimator or other detection reducing device is used, the preferred distance from the diamond will increase due to the narrowing of the detection range. Also, within the preferred range, the distance may also increase as the filter diameter narrows. Similar adjustments may be made within the preferred ranges, such as adjusting the particular height selected for the rotating platform or adjusting the diamond size and position. Slight adjustments may optionally be made to adjust to change the diameter of the measurement chamber and platform or to change the distance of the diffuser to the gemstone. Although light emanating from the gemstone to be detected at a particular angle may be detected indirectly, for example by using a mirror, direct detection as shown in fig. 5 is preferred.

In fig. 5, the preferred gauge comprises a movable measurement chamber 110 comprising a gantry 210 and a diffuser 130. The movable measurement chamber 110 may be retracted during gemstone placement and removal to allow access to the rotating platform 50. Conversely, as shown in fig. 6, the movable measurement chamber 110 may be deployed to cover the rotating platform 50 and stabilize its rotation during light detection. As shown in fig. 5, the frame 210 is connected to the fixed base plate 200 by a rotary joint 220, wherein the rotary joint 220 includes a metal rod 222 horizontally running through the frame 210 and the fixed base plate 200. The metal rod 222 is fixed to the side of the fixing base plate 200 by nuts 225a and 225b, respectively (not shown). The coupling of the gantry 210 and the fixed base 200 allows for controlled movement of the gantry 210 and the movable measurement chamber 110 between deployed and non-deployed positions.

According to an aspect of the invention, the surveying instrument provides for a stable, consistent movement of the gantry and the movable measuring chamber and ensures a precise range of movement of the measuring chamber such that proper geometrical relations are maintained during the measurement. This aspect of the invention also prevents unnecessary contact between the rotating platform and the movable measurement chamber during light detection. For these purposes, the embodiment of the meter of the present invention shown in FIG. 5 has a rotating wheel coupling comprising a large central wheel 230 connected to a small non-central wheel 240 and a positioning rod 250 parallel to the base 140, running horizontally through both wheels. According to the embodiment shown in fig. 5, the two wheels are not concentric, whereby rotating the two wheels by circumferentially moving the positioning rod 250 may cause the small wheel 240 to gradually increase or decrease its distance from the base 140, depending on whether the movement of the positioning rod 250 is clockwise or counterclockwise. In the embodiment shown in fig. 5, the frame 210 is located in the width direction of the small wheel 240. By moving the wheels 230 and 240 using a clockwise cyclic motion of the positioning rod 250, as shown in FIG. 6, the gantry 210 and the measurement chamber 110 will be gradually and steadily lowered into the deployed position. Conversely, as shown in fig. 5, the holster 210 may be raised into the non-deployed position by a reverse cyclical motion of the positioning rod 250.

According to the embodiment of fig. 5, the movement of the positioning rod is inhibited by a slotted track (not shown) located in a coupling 260, wherein the coupling 260 couples the two wheels 230 and 240. The positioning rod 250 is rotated by a track (not shown) until the positioning rod reaches the stopper 270, at which time the movable measurement chamber 110 is fully deployed on the rotating platform 50. The actuator 270 then prevents the movable measurement chamber 110 from being lowered in a manner that would interfere with the photodetector detection path, the rotating platform rotation, or the appropriate geometric measurement relationship between the various meter elements. In a preferred embodiment, the movable measurement chamber is locked in position during light detection. Thus, the embodiment of FIGS. 5 and 6 advantageously uses the coupling wheels 230 and 240 to move and the brake 270 to achieve stable and consistent placement of the movable measurement chamber. However, other mechanical mechanisms, as known in the art, may be used to achieve the same result.

Fig. 7 shows a perspective angular view of another embodiment of the present invention, wherein the present invention comprises a swing arm 280 having a dark reference 290 for measurement calibration. The swing arm 280 may be movably connected to the base 140 so that it may be moved from a non-deployed position, shown in fig. 7, to a deployed position, shown in fig. 8 in a nearly deployed state. Fig. 8 illustrates the fig. 7 embodiment and the deployed swing arm 280 beginning to place the dark reference 290 on the light detector conduit 170 (not shown) so that the user can obtain a dark reading.

In the embodiment shown in FIG. 7, the measurement chamber 110 is shown in a non-deployed mode. The measurement chamber 110 is a hollow cylinder with a hole in its side that allows light to pass from the chamber to the light detector. As shown in this embodiment, the measurement chamber 110 is also integrated with the frame 210. Alternatively, however, the measurement chamber and the housing may be provided as a single piece. As further shown in the embodiment of fig. 7, the measurement chamber 110 is covered by a diffuser 130, which is integrated within the gantry head 320. Alternatively, the diffuser 130 may cover only the measurement chamber, and need not cover the gantry head. Furthermore, although fig. 7 discloses a measurement chamber, in another embodiment the measurement chamber is fixed and the light detector is movable to allow placement and removal of the gemstone.

In another embodiment of the present invention, as shown in FIG. 9, the system includes drift correction components, including a second photodetector, and also includes a fiber optic cable 400 that is directed at an angle between 0 and about 45 degrees to the reference material measurement chamber 430 and the reference platform (not shown). The reference material measurement chamber 430 and the reference platform (not shown) are made of the same material and preferably use the same type of diffuser as the main measurement chamber and the rotating platform. The second photodetector comprises a fiber optic cable 400 that is positioned at the same angle with respect to the reference platform as the first photodetector with respect to the rotating platform 50, wherein the first photodetector comprises the fiber optic cable 30. The drift correction component can provide data, either stably or dynamically, to a data processor and/or light measuring device, which in turn corrects for electronic drift and/or interference of the system. The drift correction component may be included as an integral component of the meter or may be provided separately, as shown in fig. 9. Preferably, the drift correction component uses the same light source and illumination angle as the main measurement chamber. Although the embodiment of fig. 9 shows that both the photodetector and drift correction components comprise fiber optic cables, other types of photodetector assemblies may be used as are known in the art.

Figure 10 shows a combination diagram of one embodiment of the system of the present invention. The embodiment of fig. 10 includes a light box 20, a meter 500, a diode array spectrophotometer 600, a data processor 700 and a monitor 800. Fig. 10 shows a particular embodiment of the system of the present invention, where the entire meter 500 of fig. 5 is mounted on a microscope base 630, which has a mounting platform 635. The microscope base plate can be used for height and distance adjustment of the measuring instrument with respect to the light source. The microscope base plate may also control the movement of the light detector containing the optical fiber 30 relative to a measurement chamber, which is separately housed in a light box. Referring to, for example, fig. 2, the output of the photodetector comprising the fiber optic cable 30 is provided to a light measuring device 600, which is preferably a spectrophotometer, according to the fig. 10 embodiment. Although as shown in the present embodiment, the photodetector comprises a diode array, which is itself part of the light measuring apparatus, i.e. a diode array spectrophotometer, as an alternative the diode array together with the fibre optic cable forms part of the housing of the photodetector. Alternatively, the light detector may comprise a spectrophotometer with a collimator lens that detects light directly without passing through a fiber optic cable.

According to the embodiment shown in fig. 10, the light measuring device 600 provides the measurement data to an optical analyzer, a data processor 700, which in turn compares the measurement data to historical precedent and/or converts the measurement data to a standard CIE chromaticity space. The data processor 700 may also assign a color grade to the gemstone that meets historical precedent or simply identify the gemstone. The results of the data processor analysis may optionally be displayed on a monitor 800, output on a printer or electronically stored. The measurement data itself may be displayed graphically, in addition to or instead of gemstone color identification.

According to a preferred embodiment shown in fig. 11, to receive the gemstone, the height adjustment, angle adjustment and distance adjustment of the light detector relative to the surface receiving the gemstone are accomplished by a positioning assembly 900, which is secured to the base 140. FIG. 11 shows an integrated meter in which the fiber optic cable 30 is secured to the positioning assembly 900 by means of an angle adjuster 910. As shown in fig. 11, angle adjuster 910 is pivotally connected to distance adjuster 930, which in turn facilitates adjustment of the distance of the light detector to the surface receiving the gemstone by means of support 940 of positioning assembly 900 being movable. Also height adjuster 920 allows vertical movement of support 940 to facilitate light detector height adjustment. In this way, the present invention provides a compact, fully adjustable, integrated surveying instrument which is easy to deploy under near daylight illumination. Alternatively, the light detector may be permanently fixed to the integral measuring device at an appropriate angle, height and distance relative to the surface on which the gemstone is received. In a preferred embodiment, the light source itself forms part of an integral unit with the measuring instrument, in order to self-provide the illumination and measuring means. The overall illumination and measurement device may also be reduced in size so as to be portable.

Fig. 12 shows a preferred embodiment of the invention, where the meter of fig. 11 is housed in a light box 20. As shown in the embodiment of fig. 12, the cylinder 150 extends from the floor of the lightbox housing 20 and rotates the rotary platform 50 (not shown) against the rotator 70, which rotator 70 is disposed below the floor of the lightbox housing 20. The bottom 140 of the meter has a circular hole that allows the meter to be securely placed on the cylinder 150. Alternatively, in a non-rotating embodiment, the entire meter, including the platform, is freely placed in the light box 20. As mentioned above, the illumination source and the gauge may be comprised of an integral unit.

Turning to an exemplary method of the present invention, according to a preferred method, a diamond 40 is placed table down on a rotating platform 50, illuminated with a near daylight light source and rotated 360 degrees at a fixed speed, and light is detected by a light detector through an aperture in the measurement chamber 110. The light detector transmits the illumination response of the gemstone to the optical measurement device 600, which in turn provides measurement data to the data processor 700. The data processor provides the final color identification by averaging the measurements over a 360 degree rotation of the gemstone. The rotational aspect of the invention improves the reproducibility of the results, especially for poorly cut diamonds.

According to an aspect of the invention, the processor may average each measurement, give each measurement an equal weight, or alternatively provide a weighted average. For example, the processor may provide a height average that corresponds to a visual analysis location for visual analysis of a quality shaped diamond. For all gemstones, the processor may then convert the data to CIE chromaticity space and/or compare the data to historical precedent. Although by this method measurements of the entire multi-rotation process are evaluated to improve accuracy and reduce mechanical stress on the system, a minimum amount of rotation of the gemstone is preferred and a single rotation is most preferred.

As far as materials are concerned, the diffuser of the present invention is preferably made of a thin PTFE sheet (about 4mm), or other suitable equivalent material, which reduces the disturbing effects of direct light reflection and diffusion. Preferred materials have minimal absorbance in the visible or near visible UV spectrum. Also, the measurement chamber and the rotating platform are preferably made of a diffuse, white reflective material such as PTFE, althoughBarium sulfate orTo the extent that they have minimal specific absorption in the visible or near-visible UV spectrum, may be used. The rotator of the invention preferably comprises a positive mechanism for rotating the gemstone through 360 degrees, most preferably a continuous load motor, for example a synchronous 3W ac continuous load motor.

According to one aspect of the invention, in a preferred embodiment, the invention uses a high frequency ballast in combination with a near daylight fluorescent lamp to provide a more stable light intensity and color distribution and to improve the reliability of the measured data. In the most preferred embodiment, the high frequency ballast has a frequency of about 30000 and 70000Hz, and the most preferred frequency is about 35000 Hz.

As disclosed herein, the present invention has several advantages over prior systems, devices, and methods. First, because the light detection mechanism of the present system is close to the gemstone visual color analysis method, the present invention more closely achieves the visual color analysis results. Moreover, because the system of the present invention uses near daylight lamps, the system achieves results that are more relevant to visual color analysis. Also, because the optical measuring device can make multiple measurements for a single rotation of the gemstone, for example using a fast spectrophotometer measuring device, the instrument results in extremely fast and reproducible color analysis. Finally, certain components of the present invention, such as the diffuser, overcome the substantial difficulties associated with near vision gemstone analysis methods.

The foregoing invention and principles may also be modified for analysis of premium colored diamonds and other colored gemstones. In a novel system that uses these principles to analyze premium color diamonds and other color gemstones, the detector of the present invention preferentially detects light from the crown facet of the stone at a particular angle between about 60 and 85 degrees relative to the table of the stone. However, according to a preferred embodiment, the detector may detect light emitted from the quality color diamond and other color gemstones at more than one angle, either sequentially or simultaneously, but within a particular range of angles, preferably between about 60 and 85 degrees relative to the table of the gemstone. Multi-angle inspection within a particular angular range may be accomplished by moving during inspection, using multiple detectors, using a wide-angle detector, and/or tilting a platform or other gemstone receiving surface during inspection. If multiple angle detection sequences occur within a particular angular range, sequential changes in angle occur preferentially for a rotating gemstone after full rotation. According to this embodiment, in the case of simultaneous detection, the detector or detectors preferentially detect multiple angles within a particular range of angles during a single rotation for a rotating gemstone. The system also includes a daylight-equivalent light source that diffusely illuminates the crown facets of the gemstone.

Although a particular system, apparatus and method have been described for measuring and analyzing the color of a gemstone, it will be apparent to those of ordinary skill in the art that other embodiments and selection steps are possible without departing from the spirit and scope of the invention. For example, gemstones are often analyzed for their fluorescence. The system, apparatus and method may be used to innovatively analyze the fluorescence color or fluorescence intensity of a diamond or other gemstone by using an ultraviolet light source rather than an approximately daylight source, and a detector capable of detecting fluorescence. It will be further apparent that certain features of each embodiment disclosed herein may be used in combination with the systems and apparatus set forth in the other embodiments. The description is thus to be regarded as illustrative instead of limiting, and the scope of the invention is given by the appended claims.

Claims (32)

1. A diamond color measurement apparatus comprising:

a light source approximating daylight;

a surface for receiving a diamond;

a light detector arranged to detect light from said daylight-approximating light source emanating from the pavilion facet of a table-side-down diamond at an angle of between 0-45 degrees when said surface receives such diamond, wherein said table-side-down diamond is illuminated from its pavilion side; and

an optical measuring device for measuring the light detected by the light detector.

2. The diamond color measurement apparatus of claim 1 further comprising:

a diffuser.

3. The diamond color measurement apparatus of claim 1 wherein:

the light detector detects light from the daylight-approximating light source directly emerging from the pavilion facet of the table-faced down diamond.

4. The diamond color measurement apparatus of claim 1 further comprising:

a diffuser disposed outside a detection path of the light detector.

5. The diamond color measurement apparatus of claim 1, 2 or 3 wherein said surface comprises a platform.

6. The diamond color measurement apparatus of claim 1, 2 or 3 wherein said surface comprises a rotating platform.

7. The diamond color measurement apparatus of claim 1, 2 or 3 wherein said surface comprises a rotatable platform capable of rotating 360 degrees.

8. The diamond color measurement apparatus of claim 1, 2 or 3 further comprising a measurement chamber that at least partially surrounds the diamond when said surface receives such diamond.

9. The diamond color measurement apparatus of claim 1, 2 or 3 wherein said surface comprises a rotating platform and a rotating body which may be configured to allow measurement by said optical measurement device during a complete rotation.

10. The diamond color measurement apparatus of claim 2 wherein said diffuser at least partially blocks light from directly illuminating a diamond when such a diamond is received by said surface.

11. The diamond color measurement apparatus of claim 1, 2 or 3 wherein said surface is a white reference for calibration purposes.

12. A diamond colour measurement apparatus according to claim 1, 2 or 3, wherein said light detector is aimed at a horizontal mid-point of a diamond when said surface receives such a diamond.

13. The diamond color measurement apparatus of claim 2 wherein said diffuser is a light transmissive diffuser.

14. The diamond color measurement apparatus of claim 5 wherein said diffuser is a light transmissive diffuser.

15. The diamond color measurement apparatus of claim 1, 2 or 3 wherein said light detector further comprises a collimator.

16. The diamond color measurement apparatus of claim 3 further comprising a diffuser.

17. A diamond color measurement system comprising:

a surface for receiving a diamond;

a daylight-approximating illumination source for illuminating said diamond when said surface receives said diamond;

a light detector arranged to detect light emanating from the pavilion facet of said diamond at an angle between 0 and 45 degrees from a table-side down, when said surface receives said diamond, wherein said table-side down diamond is illuminated from its pavilion side; and

an optical measuring device for measuring the light detected by said light detector.

18. The diamond color measurement system of claim 17, further comprising:

a diffuser disposed between said illumination source and said diamond contained by said surface.

19. The diamond color measurement system of claim 17 wherein:

the light detector detects light directly emanating from the pavilion facet of the table-faced down diamond.

20. The diamond color measurement system of claim 17, 18 or 19 further comprising an optical analysis device for processing the measurements measured by said optical measurement device.

21. The diamond color measurement system of claim 17, 18 or 19 wherein said surface comprises a rotating platform.

22. The diamond color measurement system of claim 17, further comprising:

a diffuser disposed between the illumination source and the platform.

23. The diamond color measurement system of claim 17, 18 or 19 wherein said optical detector can be rotated around said surface.

24. A method of analyzing the color of a non-fancy-colored diamond comprising the steps of:

illuminating the diamond table down with a light source that diffuses near daylight;

detecting light from a light source emanating from a pavilion facet of said diamond at a specific angle between 0-45 degrees;

measuring the detected light with an optical measuring device; and

the measured values were analyzed with an optical analysis device.

25. The method of analyzing the color of a non-fancy-colored diamond of claim 24 further comprising the step of rotating said table-down diamond during said detecting step.

26. The method of analyzing the color of a non-fancy-colored diamond of claim 24 further comprising the step of rotating said diamond with said table facing downward a total of 360 degrees during said detecting step.

27. The method of analyzing the color of a non-fancy-colored diamond of claim 24 wherein said illuminating step comprises illuminating with daylight-approximating light.

28. The method of analyzing the color of a non-fancy-colored diamond of claim 24 further comprising the step of placing said diamond table face down on a platform.

29. The method for analyzing the color of a non-fancy-colored diamond of claim 25 further comprising the step of placing said diamond on a closed platform.

30. The method of analyzing the color of a non-fancy-colored diamond of claim 24 further comprising detecting light emanating from said diamond pavilion facets at a second specific angle between 0 and 45 degrees.

31. The method of claim 30, wherein the step of detecting light emanating at a second specific angle between 0-45 degrees is performed simultaneously with the step of detecting light emanating at a first specific angle between 0-45 degrees.

32. A method of analyzing the color of a non-fancy-colored diamond comprising the steps of:

illuminating the diamond table down with a light source that diffuses near daylight;

detecting light from the light source at a plurality of angles in a particular range of angles between 0-45 degrees from the diamond pavilion facet;

measuring the detected light with an optical measuring device; and

the measured values were analyzed with an optical analysis device.