Abstract: Disclosed are methods and devices for assessing the colors of diamonds. In embodiments, the color of finished diamonds cut from a given rough diamond is assessed by analyzing the effect on light interacting with the rough diamond to give a reasonable (that is to say commercially significant) assessment of the color quality of the finished diamond.

Abstract: The present invention is an engraved gemstone viewer for viewing a smooth surface of a gemstone that has been micro or nano etched, engraved or embossed with an inscription such as an identification number. The gemstone is mounted on a piece of jewelry or can remain unmounted when received by the viewer. A source of light directs a light beam toward a magnifying lens coated with a reflection enhancing coating. The lens reflects the light beam along a path incident to the surface of the gemstone containing the inscription. The smooth gemstone surface specularly reflects the light beam along a path back toward the magnifying lens, which produces a viewable light image that reveals the inscription. The inscription is shown as a combination of darkened or lightened areas, lines and characters given the reduction or absence of light reflected, or highlighted by the reflection of light.

Abstract: Systems and methods, for the evaluation, grading, and presentation of evaluation results, of the scintillation of gemstones, such as diamonds. Specifically, there are discussed systems and methods for determining when a scintillation event in a gemstone is likely to occur and for mapping such events to a presentation.

Abstract: A method of determining the position of inclusions in a gemstone, comprising: (a) placing the gemstone within a material having a refractive index within 0.5, optionally 0.2 or 0. 1, of that of the gemstone; (b) illuminating the gemstone and imaging the illuminated gemstone; and (c) determining the position of inclusions based on images of the inclusions in the images.

Abstract: A gemstone fluorescence measuring device according to the invention generally includes an ultraviolet (“UV”) emission chamber, a UV radiation source, and a light meter assembly. The UV radiation source includes an upper light emitting diode (“LED”) and a lower LED that radiate a gemstone under test from both above and below the gemstone. The UV radiation source provides both trans-radiation and direct radiation to the gemstone, and the UV radiation source has an adjustable intensity, thus facilitating calibration of the fluorescence measuring device. The light meter assembly includes a light detector that detects the visible light emitted from the gemstone under test in response to the UV radiation. The light detector is configured to simulate the spectral characteristics of the human eye. The fluorescence measuring device converts the measured visible light into a numerical lux reading, which can then be converted into a fluorescence grade for the gemstone under test.

Abstract: A method and apparatus for characterizing objects. The method includes the steps of illuminating the object with incident red light having at least some wavelengths between 620 nms and 650 nms and detecting red light fluorescence from said object having a wavelength greater than visible wavelengths greater than that of the incident wavelengths, for example by using a filter. An apparatus including a source of red incident light, a detector for longer wavelength fluorescent light and a means for physically removing the detected objects from the rest is also provided. An embodiment of the present invention may be used in a mine, for example, to separate gem stones from less valuable ore rock or in prospecting to detect the presence of gems. In this embodiment the detection is not possible with the naked eye alone.

Abstract: The present invention is an engraved gemstone viewer for viewing a flat, smooth surface of a gemstone that has been micro or nano etched with an inscription such as an identification number. The gemstone is mounted on a piece of jewelry or can remain unmounted when placed inside or otherwise received by the viewer. A source of light directs a light beam toward a magnifying lens coated with a reflection enhancing coating. The lens reflects the light beam along a path incident to the surface of the gemstone containing the inscription. The smooth flat gemstone surface spectrally reflects the light beam along a path back toward the magnifying lens, which produces a viewable light image that reveals the inscription. The inscription is shown as a dark or lightless region of the light image.

Abstract: An apparatus for determining the shape of a gemstone, including irregularities on its surface, is provided, The apparatus comprises a platform adapted to support the gemstone, a scanning system adapted to provide geometrical information concerning the three-dimensional convex envelope of the gemstone, an illumination system adapted to project on the gemstone a plurality of laser beams, an imaging system adapted to capture reflections of at least a part of said laser beams from the surface of the gemstone, and a processor. The processor is adapted to calculate, based on said geometrical information, a predicted reflection of each laser beam, to compare the captured reflections with said predicted reflections and to relate each captured reflection to its corresponding predicted reflection, to determine said shape of the gemstone based on the comparison and said geometrical information.

Abstract: An apparatus, system and method for providing spot lighting for observing a gemstone is presented. In particular, the spot lighting provided by the invention allows for observing of the fire of a gemstone, i.e. the visible effects of light dispersion into separate colors. The apparatus includes a tube for receiving a portion of a multi-spectral light source, and a mask coupled to the tube for blocking other portions of the light source. By selecting the proper tube dimensions and aligning the tube with both the light source at an inlet and a gemstone at an outlet, the spot lighting source provides direct lighting for isolating and accentuating the effects of fire.

Abstract: An apparatus that automatically captures, stores and analyzes images of crystallization experiments contained in a number of crystallization plates. The apparatus includes a plate nest capable of accommodating protein crystallization plates of a plurality of different types, image acquisition optics, including an objective lens and an image capturing device, for focusing an image of a crystallization well, a light source including a bright field illumination device and a dark field illumination device, a nest positioning controller for moving the position of the plate nest with respect to the image acquisition optics to align various selected wells with said objective lens for imaging of the content of the wells. A database stores experiment information associated with each of the crystallization plates, the experiment information including identification of specific crystal forming parameter values, each of the crystallization plates is identified in said database by a unique identification code.

Abstract: An apparatus for determining location of at least one inclusion in a gemstone having a first refractive index, comprising: a container adapted for containing a material having a second refractive index, a holder operative to support a gemstone in the material when the container contains the material; an illuminator positioned and adapted to illuminate said gemstone when disposed within said material in said container, with illumination at which said gemstone and said material have their respective first and second indices; a detector that detects illumination from the illuminated gemstone and said material and produces signals responsive thereto; a controller that receives the signals and is operative to determine a location of an inclusion in the gemstone based on the signals; and a system, operative to reduce the presence within said material, at least when the gemstone is disposed therein, of any substance other than inclusions, having a third refractive index.

Abstract: A system and method for determining macromolecule crystallization conditions by measuring the polarization anisotropy of a fluorescent probe attached to the macromolecule in solution as a function of a variation in crystallization conditions. In one exemplary embodiment, the concentration of the macromolecule material is varied and the polarization anisotropy as a function of concentration gives an indication of the proximity to crystallization conditions. A pulse illumination system with time gated detection is disclosed to isolate fluorescence response from excitation to reduce noise due to scattered and reflected light. A microassay system is disclosed to allow a complete 96 condition screen with less than 1 micro-liter of solution.

Abstract: A viewing apparatus for viewing a surface of a gemstone comprising an adjustable platform with a surface adapted to receive the gemstone is disclosed. The apparatus includes a viewing axis along which the gemstone is viewed, a light source to emit light substantially parallel to the viewing axis, and an adjustment mechanism having misalignment indicators, arranged to provide three or more visually distinguishable zones around the viewing axis. The adjustment mechanism also has three or more adjustment indicators positioned relative to the platform and the misalignment indicators, where the adjustment indicators are associated with the visually distinguishable zones such that an image viewed along the viewing axis of one of the zones reflected from the surface of the gemstone provides an indication of which way to adjust the platform relative to the viewing axis to make the surface of the gemstone perpendicular to the viewing axis.

Abstract: An arrangement and a method are provided for non-destructively analyzing the composition of a delicate sample. The value of the sample depends at least partly on absence of visual defects. A laser source (301) produces a pulsed laser beam, and focusing optics (302) focus said pulsed laser beam into a focal spot on the sample. A sensor (312) receives and detects optical emissions from particles of the sample excited by said pulsed laser beam. A processing subsystem (111) produces information of the composition of the sample based on the optical emissions detected by said sensor (312).

Abstract: Methods for grading gemstones, apparatus for grading gemstones, and systems that utilize such methods and apparatus are disclosed.

Abstract: Methods for grading gemstones, apparatus for grading gemstones, and systems that utilize such methods and apparatus are disclosed.

Abstract: The present invention discloses an apparatus and method for color measurement and color grading of faceted gemstones, diamonds and the like. The apparatus comprises a spectrometer, a computer, and a dual integrating sphere measurement arrangement comprising a measurement integrating sphere, a sample integrating sphere, a sample platform, a filter, a lens system, a baffle and a light source. The measurement geometry of the dual integrating sphere measurement arrangement is diffuse illumination and 8 degree viewing with the specular component excluded, plus diffuse white background provided by the sample integrating sphere. The sample integrating sphere encloses a sample to provide a constant environment for simulating the visual color grading environment. A novel three-step calibration insures an accurate spectral measurement of the sample inside the measurement integrating sphere.

Abstract: An online method and system for evaluating a gemstone is provided that enables a consumer to use a personal computer to evaluate the visual appearance and measurement data of the gemstone by emulating the laboratory instruments that previously collected the data for the gemstone. The computer is connected to the internet and a website that is linked to a gemstone database, emulation software and graphical user interface. The consumer identifies the specific gemstone he or she wants to evaluate, and an interactive gemstone certificate screen is displayed. The consumer separately selects and then emulates a variety of lab instruments, such as color and clarity grading, geometric measuring, and light performance and light ray tracing instruments. Graphical images and data pertaining to the selected gemstone are displayed on the computer monitor, and selected portions of the database are downloaded and saved on the computer memory.

Abstract: An apparatus configured to generate image data for use in determining a property of a gemstone is disclosed. The apparatus includes a support structure configured to support the gemstone at an observation position such that an axis of symmetry of the gemstone is substantially parallel to an axis of rotation of the apparatus, a light source, including a reflector having a concave surface arranged to reflect a spatially varied light pattern generally towards the observation position, the concave surface including at least one relatively reflective region and at least one relatively unreflective region and is configured to generate the light pattern, where the length of a boundary between the relatively reflective region and the relatively unreflective region is greater than the radial distance between the center and an edge of the concave surface, and a rotator configured to rotate the gemstone relative to the light pattern substantially about the axis of rotation.

Abstract: A method and system, including a computer program product, implementing a color terminology for accurate color grading of gemstones are provided. The method includes generating a reference color to match that of a graded gemstone under the standard viewing environment, processing color data in different color spaces, assigning a color grade to specify the color of the gemstone graded. The reference color can be continuously changed by adjusting the hue, lightness and saturation values. The color grade comprises a color name and one or more corresponding color coordinates and/or one or more corresponding color notations, in the form of Color Name (Color Coordinates). The color name is used for verbal description of the color, and the color coordinate or color notation is for accurate color communication in the jewelry industry.

Abstract: Methods for grading gemstones, apparatus for grading gemstones, and systems that utilize such methods and apparatus are disclosed.

Abstract: Systems and methods for evaluating an optical property of a gemstone operate to trace selected and ordered model light rays through a model of the gemstone. The rays may be selected such that, when ordered into a sequence, the points of contact of successive rays with the gemstone surface generate a pattern defined by a path created by the linking of successive contact points with line segments. Further, the rays may be propagated through the gemstone in a manner that utilizes an ordered set of facet identifiers corresponding to facets impinged upon by a ray previously propagated through the gemstone. Moreover, these strategies can be combined by propagating an ordered sequence of rays corresponding to an ordered set of contact points generating a pattern defined by a path, and using for such propagation an ordered set of facet identifiers corresponding to facets impinged upon by a ray previously propagated through the gemstone.

Abstract: A crystal optical material is illuminated at a wavelength of light that does not ionize the crystal optical material. Birefringence is measured between a plurality of voxels within the crystal optical material having spatial dimensions small enough to distinguish optical propagations of the light encountering boundary regions between subgrains of the crystal mosaic from optical propagations of the light through the subgrains themselves. The measured birefringence is evaluated for quantifying a characteristic of the crystal matrix. Metrics describing the crystal matrix are associated with performance of the crystal optical material.

Abstract: Methods for grading gemstones, apparatus for grading gemstones, and systems that utilize such methods and apparatus are disclosed.

Abstract: A method for improving accuracy of determining polish endpoint of chemical mechanical polish (CMP) process is provided. The method is performed before the CMP process. First, a test wafer with a to-be-polished layer and a material layer under the to-be-polished layer is provided. Then, a test beam with a wavelength is provided to irradiate the test wafer. The CMP process is performed to the test wafer to remove the to-be-polished layer until the material layer is exposed while the reflection of the test beam during the polish process is continuously detected. The reflection tendency is detected when the to-be-polished layer is to be completely removed and when the CMP process reaches the interface between the to-be-polished layer and the material layer. If the reflection tendency is gradually weakened, the test beam with the wavelength is chosen for the subsequent polish process.

Abstract: Systems and methods for evaluating and displaying a diamond's dispersion or fire potential. These systems and methods can be used to determine the dispersion of a diamond relative to an observation point, which can then be used to provide for a map or other indicator of a diamond's fire potential when it is observed from that point.

Abstract: In-situ monitoring of a crystallization state is used for laser anneal processing for applying an energy line irradiation for at least one of crystallization of a thin film and promotion of the crystallization. A method is characterized by simultaneously irradiating at least a plurality of monitoring places in a region having a predetermined area of at least one of the surface and the underside of the thin film by a monitor light for monitoring a crystallization state of the thin film at least during or after of before, during and after the energy line irradiation directly or through a substrate, and measuring a temporal change of the intensity of at least one of a reflected light and a transmitted light, from the surface or the underside of the thin film, of the monitor light as a light intensity distribution related to the positions of the monitoring places. Apparatus according to the invention perform such methods.

Abstract: Methods for grading gemstones, apparatus for grading gemstones, and systems that utilize such methods and apparatus, specifically methods which trace rays through a computer representation of a gemstone wherein the rays enter the gemstone though the gemstone crown and allow a grade to be assigned to the gemstone represented based on the ray paths through the representation.

Abstract: An apparatus for detecting one or more organic compounds in a gem, comprising a probe for irradiating a surface of a gem with near infrared radiation, to generate internal reflections of the near infrared radiation within the gem, wherein the internal reflections are substantially diffuse; a near infrared radiation transmissive conduit for collecting internally reflected near infrared radiation from a surface of the gem, the internally reflected energy comprising components which are diffuse; a spectrometer for analyzing the collected internally reflected diffuse near infrared radiation from the gem, to determine if spectral characteristics indicative of at least one organic compound are present in the gem.

Abstract: The present invention is directed to a device for imaging a gem, and more specifically, a device capable of imaging the fire of a gem and thereby enabling the qualitative assessment of the fire of the gem. The gem imaging device of the present invention includes an exterior assembly and an inner assembly. The exterior assembly includes a viewing system, an outer housing and a base, while the inner assembly includes a view opening, a light baffle, an illumination mechanism, a diffuser plate mechanism, an outer chamber, an inner chamber, a perforated inner compartment and a rotation mechanism. In use, a user images a gem located in the inner assembly of the gem imaging device, and specifically, located within the inner chamber. Based on the light reflected on, into or from the gem, the user may image the gem, and specifically, the fire of the gem.

Abstract: An apparatus for determining the shape of a gemstone, including irregularities on its surface, is provided, The apparatus comprises a platform adapted to support the gemstone, a scanning system adapted to provide geometrical information concerning the three-dimensional convex envelope of the gemstone, an illumination system adapted to project on the gemstone a plurality of laser beams, an imaging system adapted to capture reflections of at least a part of said laser beams from the surface of the gemstone, and a processor. The processor is adapted to calculate, based on said geometrical information, a predicted reflection of each laser beam, to compare the captured reflections with said predicted reflections and to relate each captured reflection to its corresponding predicted reflection, to determine said shape of the gemstone based on the comparison and said geometrical information.

Abstract: A laser crystallization apparatus, which enables an observation of a high spatial resolution with several ?m and a high temporal resolution with several nanoseconds, comprising a crystallization optical system to irradiate a laser light to a thin film provided on a substrate and to melt and crystallize the thin film, the laser crystallization apparatus comprises an illumination light source disposed out of an optical path of the laser light and emitting an illumination light for observation to illuminate the thin film, an illumination optical system comprising an annular optical element which has the optical path of the laser light in the center and which leads the illumination light from the illumination light source to the thin film along the optical path, and an observation optical system which displays a magnified image of the substrate including the thin film.

Abstract: The invention concerns a method for qualifying a diamond on the basis of a measured light transmission through the diamond, whereby the diamond is radiated by a light source which emits light having a wavelength in a range of 225 nm to 300 nm, whereby the transmission of said light through the diamond is compared to a reference value which corresponds to the transmission of said light through a reference diamond, which is a cut colourless or near colourless diamond with a concentration of A centers between 7 ppm and 22 ppm, and whereby the diamond is classified as natural and not colour-treated if the transmission through the diamond is smaller than or equal to the reference value.

Abstract: A gemstone fluorescence measuring device according to the invention generally includes an ultraviolet (“UV”) emission chamber, a UV radiation source, and a light meter assembly. The UV radiation source includes an upper light emitting diode (“LED”) and a lower LED that radiate a gemstone under test from both above and below the gemstone. The UV radiation source provides both trans-radiation and direct radiation to the gemstone, and the UV radiation source has an adjustable intensity, thus facilitating calibration of the fluorescence measuring device. The light meter assembly includes a light detector that detects the visible light emitted from the gemstone under test in response to the UV radiation. The light detector is configured to simulate the spectral characteristics of the human eye. The fluorescence measuring device converts the measured visible light into a numerical lux reading, which can then be converted into a fluorescence grade for the gemstone under test.

Abstract: Prior methods of measuring diamond proportions in order to construct a complete model, such as a three dimensional virtual wire-frame model, of a diamond have been found to be inadequate. In particular, there has been no commercially available, automated and objective method for measuring the dimensions of a diamond with similar or greater accuracy as compared with the accuracy that can be achieved with manual gauges or micrometers. The present invention provides a method of measuring a physical characteristic of a facet of a diamond, such as the location of one or more points on an edge of a facet. The method comprises illuminating the diamond to visually distinguish a facet from adjacent facets when viewed from a predetermined location, and then capturing an image of the diamond as viewed from this predetermined location.

Abstract: Of the “four C's,” cut has historically been the most complex to understand and assess. This application presents a three-dimensional mathematical model to study the interaction of light with a fully faceted, colorless, symmetrical round-brilliant-cut diamond. With this model, one can analyze how various appearance factors (brilliance, fire, and scintillation) depend on proportions. The model generates images and a numerical measurement of the optical efficiency of the round brilliant—called DCLR—which approximates overall fire. DCLR values change with variations in cut proportions, in particular crown angle, pavilion angle, table size, star facet length, culet size, and lower girdle facet length. The invention describes many combinations of proportions with equal or higher DCLR than “Ideal” cuts, and these DCLR ratings may be balanced with other factors such as brilliance and scintillation to provide a cut grade for an existing diamond or a cut analysis for prospective cut of diamond rough.

Abstract: System and method for providing a gem assessment based upon proportional parameter values relating to the proportions of a gem, such as a diamond. A gem cut quality rating is provided. The system and method are particularly suited for use in an online environment or may be utilized in conjunction with rough diamond analysis instruments in order to provide cutters with greater guidance as to the most appropriate dimensions to cut rough diamonds in order to maximize the yield of a rough diamond and to also produce a diamond of an acceptable grade.

Abstract: A mechanism for always measuring the spatial intensity distribution of a laser beam and displacement of the optical axis of the laser beam is provided so that a measured signal is processed when the laser beam incident on a laser beam shaping optical element is out of a predetermined condition. The shape, diameter and incidence position of the laser beam incident on the laser beam shaping optical element are always kept in the predetermined condition by a spatial filter disposed at the position of a focal point of lenses forming a beam expander disposed in the optical axis, on the basis of a result of the signal processing. In this manner, silicon thin films uniform in crystallinity can be formed stably with a high yield on an insulating substrate which forms display panels of flat panel display devices.

Abstract: An apparatus and associated method for the direct and objective grading of the cut and symmetry of gemstones is provided. The apparatus comprises a laser, an integration sphere, and a gemstone holder, which together measure certain optical characteristics of the gemstone. Optionally, the gemstone holder mechanically rotates and the integration sphere connects to a data recorder such that a plurality of measurements may be recorded and analyzed. The associated method provides a method for interpretation of the data generated by the apparatus as the data relates to the cut quality and symmetry of the gemstone.

Abstract: An inspection method and apparatus of laser crystallized silicons in the low-temperature poly Si (LTPS) process. The crystalline quality is inspected by using a visible light source to irradiate the surface of the poly Si and examining the variations of the reflected light caused by the protrusion arrangement at the surface of the poly Si. This method can be adopted on the poly Si samples prepared by the line scanning of the excimer laser annealing (ELA) technology.

Abstract: A gemstone rating system is provided particularly for rating the cut of diamonds in which particular cuts and features are measured and the results compared with and provided with a predetermined score depending upon deviations from a theoretical perfect cut; and wherein the deviation scores are summed and then subtracted from an initially perfect score to provide a universally comparable indication of quality of cut.

Abstract: Diffuse reflectance spectroscopy using near infrared and mid infrared radiation is used to detect the presence of organic chemical compounds in gems. Suitably, diffuse reflectance infrared Fourier transformation spectroscopy is employed to detect the presence of organic compounds in gems using mid infrared and near infrared radiation. The apparatus uses an integrating sphere or integrating cylinder with a probe that acts as both a source of near infrared radiation and a detector of reflected diffuse internal energy from the gem. Alternatively, the integrating sphere or integrating cylinder is replaced with a reflective fluid which surrounds the gem and causes total internal reflection.

Abstract: An apparatus, system and method for providing spot lighting for observing a gemstone is presented. In particular, the spot lighting provided by the invention allows for observing of the fire of a gemstone, i.e. the visible effects of light dispersion into separate colors. The apparatus includes a tube for receiving a portion of a multi-spectral light source, and a mask coupled to the tube for blocking other portions of the light source. By selecting the proper tube dimensions and aligning the tube with both the light source at an inlet and a gemstone at an outlet, the spot lighting source provides direct lighting for isolating and accentuating the effects of fire.

Abstract: A container has a base including a support for an object to be viewed. A container also has a lid on top of the base, the lid having a light-conveying portion for illuminating an object to be viewed and a magnifying viewer for viewing an object to be viewed.

Abstract: In an object verifier having a housing and an object holder, an object may be placed in the object holder for observation by an operator. The object is illuminated using a collimated beam of white light that is generated by a light generator. The collimated beam of white light is passed through a beam splitter with the two portions of the collimated beam of white light presented to the object at a 90 degree angle one from the other. The interior of the housing includes a reflective surface for maximal illumination of the object. The observer may view the illuminated object through a viewing window and/or through a magnification window. The magnification window provides for the viewing of the object in greater detail.

Abstract: A method and associated apparatus (5) for the standardized grading of gemstones is provided. The system gauges the spectral response of a gemstone subject to a plurality of incident light sources (77, 64, 90, 92, 102) within an imaging apparatus. The operation of the imaging apparatus is controlled by an instruction set of a local station control data processor (12). Light energy data is captured in the form of pixel data sets via a charge coupled device of the imaging apparatus of the local station (8). The control data processor data of the local station is operably linked to analysis station (14). Gemstones qualities are analyzed by the plurality of light sources (92, 90, 102) of the imaging apparatus (5) and quantified relative to model pixel data sets of the database and recorded for future reference therein.

Abstract: A film quality inspecting method comprising applying a measuring beam having a specific wavelength to an annealed silicon film formed on a substrate in a direction inclined with respect to the silicon film, measuring a reflection intensity or reflectivity of a reflection beam reflected by the silicon film as a result of the application, and inspecting a film quality of the silicon film based on a measurement value obtained by the measurement.

Abstract: An apparatus and method for performing rapid grain size analysis on a textured polycrystalline material, by generating average grain size and grain size distribution data from x-ray diffraction data of such material. Raw diffraction data is obtained by capturing a plurality of diffraction arcs within a single data capture frame. The raw diffraction data is digitally registered; (3) and the registered diffraction data is filtered to remove background noise, exclude diffraction overlaps or truncations, and compensate for biased data obtained from regions of highly preferred orientations. Average grain size and grain size distribution data are then correlated with the filtered diffraction data. The apparatus for acquiring raw diffraction data includes a collimated x-ray source having means for adjusting beam size and divergence of the x-ray generated, a 2-dimensional area detector for registering diffracted x-ray, and a sample motion assembly for moving the sample in the sample plane.

Abstract: Process for the measurement of the surface of a polished precious stone, wherein firstly the position of at least some of the flat facet surfaces of the stone is measured in space, in particular by rotating the stone in front of a light source and examination of the shadow cast by the stone, and the facet surface is then observed under direct light.

Abstract: Prior methods of measuring diamond proportions in order to construct a complete model, such as a three dimensional virtual wire-frame model, of a diamond have been found to be inadequate. In particular, there has been no commercially available, automated and objective method for measuring the dimensions of a diamond with similar or greater accuracy as compared with the accuracy that can be achieved with manual gauges or micrometers. The present invention provides a method of measuring a physical characteristic of a facet of a diamond, such as the location of one or more points on an edge of a facet. The method comprises illuminating the diamond to visually distinguish a facet from adjacent facets when viewed from a predetermined location, and then capturing an image of the diamond as viewed from this predetermined location.