Gemstone analysis system and methods

Abstract

A gemstone analysis system (100) optically analyzes a gemstone to generate a fingerprint data set uniquely characterizing the gemstone. In this system (100), an illumination arrangement (112) illuminates the gemstone with collimated light only to obtain a reflection from the gemstone that results from the collimated light only. A camera (114) comprising a telecentric lens (116) and an image sensor (117) exclusively receives reflections that result from the collimated light including the reflection from the gemstone. The reflections traverse the telecentric lens (116) to arrive at an image sensor (117). The telecentric lens (116) has an optical axis and a transmission efficiency for a light ray traversing the telecentric lens (166) that decreases as an angle between the light ray and the optical axis increases. The transmission efficiency is, on the one hand, at least 2% with respect to that for zero angle in case the angle is 1° and, on the other hand, 2% at the most in case the angle is 5°. A processor (113) generates the fingerprint data set based on an image produced by the image sensor (117) in response to the reflections that have traversed the telecentric lens (116).

Description

[0001] Gemstone analysis system and methods.

[0002] FIELD OF THE INVENTION

[0003] An aspect of the invention relates to a gemstone analysis system capable of optically analyzing a gemstone to generate a fingerprint data set uniquely characterizing the gemstone. The gemstone analysis system may be used, for example, for authenticating and identifying various types of gemstones including, for example, polished diamonds, mounted diamonds, and rough diamonds. Other aspects of the invention relate to use of a gemstone analysis system, to a method of authenticating a gemstone, to a method of identifying a gemstone, and to a method of identifying a particular gemstone among various gemstones.

[0004] BACKGROUND ART

[0005] Patent publication WO2016185472 describes a technique for generating a unique identification associated with a gemstone, usable for unique identification of the gemstone. One or more images of the gemstone are obtained. The one or more images are captured at one or more viewing angles relative to the gemstone and to a light pattern. This gives rise to a representative group of images. The representative group of images are processed to generate a set of rotation-invariant values informative of rotational crosscorrelation relationship characterizing the images in the representative group. The generated set of rotation-invariant values are used to generate a unique identification associated with the gemstone. The unique identification associated with the gemstone can be further compared with an independently generated unique identification associated with the gemstone in question, or with a class- indicative unique identification.

[0006] SUMMARY OF THE INVENTION

[0007] There is a need for a gemstone analysis technique that offers an improvement in at least one of the following aspects: analysis speed, cost, ease-of-use, and reliability.

[0008] An aspect of the invention, which is defined in claim 1, relates to a gemstone analysis system capable of optically analyzing a gemstone to generate a fingerprint data set uniquely characterizing the gemstone, the gemstone analysis system comprising: an illumination arrangement configured to illuminate the gemstone with collimated light; a camera comprising a telecentric lens and an image sensor, the camera being arranged to receive a reflection of the collimated light from the gemstone, whereby the reflection of the collimated light traverses the telecentric lens to arrive at the image sensor; and a processor configured to generate the fingerprint data set based on an image produced by the image sensor in response to the reflection of the collimated light that has traversed the telecentric lens.

[0009] A further aspect of the invention, which is defined in claim 21, relates to use of a gemstone analysis system as defined hereinbefore for generating fingerprint data set uniquely characterizing a gemstone.

[0010] Yet a further aspect of the invention, which is defined in claim 22, relates to a gemstone analysis device for use in a gemstone analysis system as defined hereinbefore, the gemstone analysis device comprising the illumination arrangement, the camera, and a communication interface adapted to transmit the image produced by the image sensor of the camera to the processor, which is external to the gemstone analysis device.

[0011] Yet a further aspect of the invention, which is defined in claim 23, relates to a method of authenticating a gemstone, the method comprising: specifying an identifier that has been assigned to the gemstone, the identifier being associated with a reference fingerprint data set that has previously been generated for the gemstone; using a gemstone analysis system as defined hereinbefore to generate the fingerprint data set uniquely characterizing the gemstone; and authenticating the gemstone as genuine if the fingerprint data set matches with the reference fingerprint data set.

[0012] Yet a further aspect of the invention, which is defined in claim 24, relates to a method of identifying a gemstone, the method comprising: using a gemstone analysis system as defined hereinbefore to generate the fingerprint data set uniquely characterizing the gemstone; interrogating a database comprising respective reference fingerprint data sets associated with respective identifiers that have been assigned to respective gemstones; identifying a reference fingerprint data set in the database that matches with the fingerprint data set that has been generated, the identifier associated with the reference fingerprint data set identifying the gemstone.

[0013] Yet a further aspect of the invention, which is defined in claim 25, relates to a method of identifying a particular gemstone among various gemstones, the method comprising: specifying an identifier that has been assigned to the particular gemstone, the identifier being associated with a reference fingerprint data set that has previously been generated for the gemstone; selecting a gemstone among the various gemstones; using a gemstone analysis system as defined hereinbefore to generate the fingerprint data set uniquely characterizing the gemstone that has been selected; identifying the gemstone that has been selected as the particular gemstone if the fingerprint data set matches with the reference fingerprint data set ; and if there is no match, selecting another gemstone among the various gemstones and continue using the gemstone analysis system for identifying the particular gemstone

[0014] In each of these aspects, a gemstone is illuminated with collimated light and an image is captured based on a reflection of the collimated light from the gemstone that has traversed a telecentric lens, which has an optical axis. This affects the image as follows. Firstly, the collimated light makes that the gemstone is illuminated by light rays coming from a single direction. As a result, there are fewer directions in which the gemstone may reflect light than if the gemstone were illuminated by light rays coming from different directions, as is the case with ambient light. Secondly, the telecentric lens makes that only reflected light rays that are parallel to its optical axis will form the image. Many reflections from the gemstone, which makes the gemstone shiny in ambient light, are effectively suppressed, leaving relatively few reflections to form the image. Nonetheless, these relatively few image-forming reflections may uniquely characterize the gemstone. What is more, the telecentric lens makes that there is no perspective effect: the image is a faithful projection of the gemstone. The image accurately represents gemstone features without distortion, particularly in terms of their relative dimensions. The image thus captured comprises relatively few details, which are accurate and uniquely characteristic of the gemstone. Moreover, these details are generally relatively easily detectable and identifiable by a processor. That is, the image is relatively easy to interpret by the processor. Accordingly, the processor may generate the fingerprint data set by means of relatively simple operations. In a basic embodiment, the fingerprint data set may even consist of the image that has been captured. In more evolved embodiments, the finger data set comprises one or features that the processor has extracted from the image that has been captured. These and other factors may thus offer an improvement with respect to prior-art gemstone analysis techniques in at least one of the following aspects: analysis speed, cost, ease-of-use, and reliability.

[0015] For the purpose of illustration, some embodiments of the invention are described in detail with reference to accompanying drawings. In this description, additional features will be presented, some of which are reflected in the dependent claims, and advantages will be apparent.

[0016] BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. l is a schematic perspective view of an exemplary gemstone analysis system.

[0018] FIG. 2 is a schematic side view of various components in the exemplary gemstone analysis system.

[0019] FIG. 3 is an explanatory diagram of a light reflection response in the exemplary gemstone analysis system.

[0020] FIG.4 is exemplary image of a gemstone captured in the exemplary gemstone analysis system.

[0021] FIG. 5 is a flow chart diagram of an exemplary method of generating a fingerprint data set uniquely characterizing a gemstone.

[0022] FIG. 6 is a flow chart diagram of an exemplary method of authenticating a gemstone.

[0023] FIG. 7 is a flow chart diagram of an exemplary method of identifying a gemstone.

[0024] FIG. 8 is a flow chart diagram of an exemplary method of identifying a particular gemstone among various gemstones.

[0025] FIG. 9 is a schematic perspective view of another exemplary gemstone analysis system. DESCRIPTION OF SOME EMBODIMENTS

[0026] FIGS. 1 and 2 schematically illustrate an exemplary gemstone analysis system 100. FIG. 1 provides a schematic perspective view of the exemplary gemstone analysis system 100. FIG. 2 provides a schematic side view of various components in the exemplary gemstone analysis system 100. The exemplary gemstone analysis system 100 may be used, for example, to optically analyze gemstones. Specifically, the gemstone analysis system 100 may generate a fingerprint data set uniquely characterizing a gemstone. The gemstone may be, for example, a polished diamond, a mounted diamond, or a rough diamond. The fingerprint data set that is generated may be regarded as a unique optical fingerprint of the gemstone. This unique optical fingerprint may be used at a later stage to authenticate the gemstone, or to identify the gemstone, or both. This will be discussed in greater detail hereinafter.

[0027] The exemplary gemstone analysis system 100 comprises a gemstone analysis unit 101, a gemstone holder 102, and a pick-and-place feeder mechanism 103. In this embodiment, the gemstone analysis unit 101 comprises a housing 104 that is provided with a slidable cap 105. In FIG. 1, the slidable cap 105 is in a rest position. The gemstone holder 102 has a circular shape forming a carousel that may hold multiple gemstones.

[0028] The housing 104 of the gemstone analysis unit 101 includes a transparent support 106 on which a gemstone may be placed. The slidable cap 105 may slide to a functional position in which the slidable cap 105 covers the transparent support 106, as well as the gemstone placed thereon. The transparent support 106 may comprise wearresistant material preventing the transparent support 106 from being scratched or otherwise damaged by gemstones or other type of objects. The transparent support 106 may comprise a glass plate, in particular a scratch-resistant glass plate. The glass plate may comprise an anti-reflective coating.

[0029] Referring to FIG. 2, the transparent support 106 has two main surfaces 107, 108 one of which will be referred to as top surface 107, while the other one will be referred to as bottom surface 108. The top surface 107 is outwardly oriented, whereas the bottom surface 108 is inwardly oriented with respect to the gemstone analysis unit 101. A gemstone that is placed on the transparent support 106 will thus generally be in contact with the top surface 107 of the transparent support 106. Specifically, the gemstone may be placed on the transparent support 106 so that a table of the gemstone is in contact with the top surface 107. The gemstone is then visible from within the gemstone analysis unit 101 through the bottom surface 108 of the transparent support 106.

[0030] Further referring to FIG. 2, a light-reflecting arrangement 109 is mounted in the slidable cap 105. The slidable cap 105 is not represented in FIG. 2, as well as the housing 104 and other components, for the sake of simplicity and clarity. The lightreflecting arrangement 109 faces the top surface 107 of the transparent support 106, as illustrated in FIG. 2, when the slidable cap 105 is in the functional position. The lightreflecting arrangement 109 may be in the form of a mirror and will be referred to hereinafter as top mirror 109 for ease of reading.

[0031] The top mirror 109 and the top surface 107 of the transparent support 106 delimit a space 110, which may be referred to as a reflection space 110. A gemstone that has been placed on the transparent support 106 is thus within this reflection space 110. Specific light reflections may then occur in the reflection space 110, which will be discussed hereinafter.

[0032] FIG. 2 illustrates various components within the housing 104 of the gemstone analysis unit 101. These include an image-capturing arrangement 111, and an illumination arrangement 112. In this embodiment, the gemstone analysis unit 101 comprises a processor 113. However, in another embodiment, the processor 113 may be external to the gemstone analysis unit 101. In such another embodiment, the gemstone analysis unit 101 may comprise a communication interface that may transmit information to an external processor, which may comprise, for example, a remote server.

[0033] In this embodiment, the image-capturing arrangement 111 comprises two cameras 114, 115: a first camera 114 and a second camera 115. The first camera 114 comprises a first telecentric lens 116 in front of a first image sensor 117. Similarly, the second camera 115 comprises a second telecentric 118 lens in front of a second image sensor 119.

[0034] The second telecentric lens 118 provides a larger magnification than the first telecentric lens 116. As a result, the second camera 115 has a smaller field of view than the first camera 114. The first camera 114 and the second camera 115 will be referred to hereinafter as large field-of-view camera 114 and as small field-of-view camera 115, respectively, for ease of reading. The first telecentric lens 116 and the second telecentric 118 lens will be referred to hereinafter as large field-of-view telecentric lens 116 and small field-of-view telecentric lens 118, respectively. The first image sensor 117 and the second image sensor 119 may be identical, or at least similar. Nonetheless, the one and the other will be referred to as large field-of-view image sensor 117 and small field-of-view image sensor 119, respectively, for ease of reading.

[0035] In this embodiment, the illumination arrangement 112 comprises two light sources, a first light source 120 and a second light source 121. The first light source 120 is adjacent to the large field-of-view camera 114. The second light source 121 is adjacent to the small field-of-view camera 115. The first light source 120 and the second light source 121 will therefore be referred to hereinafter as large field-of-view light source 120 and small field-of-view light source 121, respectively, for ease of reading. Each may be adapted to produce light for which the anti -reflective coating of the transparent support 106 is particularly effective.

[0036] FIG. 2 very schematically represents an optical path 122 that extends between the large field-of-view light source 120 and the bottom surface 108 of the transparent support 106. This optical path 122 will be referred to hereinafter as large field- of-view optical path 122 for ease of reading. In this embodiment, the large field-of-view optical path 122 includes a light reflecting arrangement 123, which may comprise a mirror. This light reflecting arrangement 123 will be referred to hereinafter as diagonal mirror 123 for ease of reading.

[0037] FIG. 2 very schematically represents a further optical path 124 that extends between the small field-of-view light source 121 and the bottom surface 108 of the transparent support 106. This further optical path 124 will be referred to hereinafter as small field-of-view optical path 124 for ease of reading. In this embodiment, the small field-of-view optical path 124 equally includes a light reflecting arrangement 125, which may comprise a semitransparent mirror. This light reflecting arrangement 125 will be referred to hereinafter as diagonal semitransparent mirror 125 for ease of reading. The diagonal semitransparent mirror 125 also forms part of the large field-of-view optical path 122, as shown in FIG. 2.

[0038] The processor 113 is operationally coupled to the small field-of-view camera 115 and the large field-of-view camera 114. More specifically, the processor 113 is coupled to the large field-of-view image sensor 117, as well as to the small field-of-view image sensor 119. The processor 113 may further be operationally coupled to a user interface, which may form part of the gemstone analysis unit 101, or which may be external thereto. The user interface may include, for example, a touchscreen allowing a user to interact with the processor 113 and the gemstone analysis system 100 in general. FIGS. 1 and 2 do not represent any user interface for the sake of simplicity and clarity. The processor 113 may further be operationally coupled to an external data handling device, which may comprise a database. The gemstone analysis unit 101 may comprise a data storage medium capable of comprising a database. FIG. 2 does not represent any data storage medium or database for the sake of simplicity and clarity.

[0039] The gemstone analysis system 100 basically operates as follows. It is assumed that the slidable cap 105 of the gemstone analysis unit 101 is in the rest position as illustrated in FIG. 1. The pick-and-place feeder mechanism 103 may pick up a gemstone from the gemstone holder 102. The pick-and-place feeder mechanism 103 may then place the gemstone on the transparent support 106 of the gemstone analysis unit 101. Specifically, the gemstone may be placed so that the table of the gemstone is in contact with the top surface 107 of the transparent support 106. The slidable cap 105 may then slide to the functional position. In this position, the top mirror 109 faces the transparent support 106 as illustrated in FIG. 2.

[0040] The large field-of-view light source 120 may generate a beam of collimated light. The beam of collimated light follows the large field-of-view optical path 122 reaching the transparent support 106 and its bottom surface 108. Specifically, the diagonal mirror 123 receives the beam of collimated light from the large field-of-view light source 120 along a first axis. The diagonal mirror 123 deflects the beam of collimated light along a second axis toward the bottom surface 108 of the transparent support 106; traversing the diagonal semitransparent mirror 125. In this embodiment, the first axis being horizontal and the second axis being vertical, these axes are perpendicular with respect to each other. The beam of collimated light traverses the transparent support 106 exiting at its top surface 107 on which the gemstone is present. Accordingly, the beam of collimated light enters into the aforementioned reflection space 110.

[0041] FIG. 3 schematically illustrates a light reflection response 300 from the reflection space 110 in the gemstone analysis system 100. FIG. 3 provides a schematic explanatory diagram of the light reflection response 300 from the reflection space 110. The gemstone that is present on the transparent support 106 is represented in FIG. 3 and denoted therein by reference numeral 301. The table of the gemstone 301, which is in contact with the top surface 107 of the transparent support 106, is denoted by reference numeral 302. The gemstone 301 further has a girdle 303 and a crown 304 between the girdle 303 and the table 302. The gemstone 301 has multiple facets, which are very schematically indicated in FIG. 3. The beam of collimated light that traverses the transparent support 106 and enters the reflection space 110 is schematically indicated in FIG.3 by densely dashed lines.

[0042] The light reflection response 300 exclusively includes light reflections that are substantially perpendicular to the top surface 107 and the bottom surface 108 of the transparent support 106. Accordingly, light reflections that have a different orientation are excluded from the light reflection response 300. Namely, these non-perpendicular orientated light reflections will effectively be prevented from reaching the large field-of- view image sensor 117 and the small field-of-view image sensor 119. This will be discussed in greater detail hereinafter.

[0043] The light reflection response 300 is determined by various light reflections that occur in the reflection space 110. Basically, there are four sources of reflections. A first source of reflection is the top mirror 109. A portion of the collimated light beam bypasses the gemstone 301 and is incident on the top mirror 109. The top mirror 109 may almost entirely reflect this portion of the collimated light beam. This is because the top mirror 109 has a relatively high reflectance, which may be close to 100%. Further, reflected light from the top mirror 109 is oriented substantially perpendicular to the top surface 107 and the bottom surface 108 of the transparent support 106.

[0044] The reflected light from top mirror 109 accounts for a first component 305 in the light reflection response 300, which is schematically indicated in FIG. 3. This first component 305 will be referred to hereinafter as the mirror-related component 305 for ease of reading. The mirror-related component 305 in the light reflection response 300 is relatively bright. This is mainly due to two factors. First, the reflected light from the top mirror 109 is oriented substantially perpendicularly as discussed hereinbefore. Second, the relatively high reflectance of the top mirror 109 makes that the mirror-related component 305 is relatively bright.

[0045] A second source of reflection is the crown 304 of the gemstone 301, more precisely, its exterior surface. The exterior surface of the crown 304 has a relatively low reflectance, significantly lower than that of the top mirror 109. Accordingly, the exterior surface of the crown 304 reflects only a portion of the collimated light that is incident thereon. Another portion of this light penetrates into the gemstone 301. What is more, since the exterior surface of the crown 304 portion is inclined with respect to the top surface 107 of the transparent support 106, reflected light is mainly directed sideways. The reflected light is non-perpendicular to the top surface 107 and the bottom surface 108 of the transparent support 106. The reflected light from the crown 304 accounts for a second component 306 in the reflection response, which is schematically indicated in FIG. 3. This second component 306 will be referred to hereinafter as the crown-related component 306 for ease of reading. The crown-related component 306 is relatively dark. This is mainly because the light reflections from the crown 304 are substantially non-perpendicularly oriented as discussed hereinbefore. In addition, the relatively low reflectance of the exterior surface of the crown 304 makes that the mirror-related component 305 is relatively dark.

[0046] A third source of reflection is the table 302 of the gemstone 301, more precisely, its exterior surface, which is in contact with the top surface 107 of the transparent support 106. The exterior surface of the table 302 has a relatively low reflectance, which may be, for example, about 17% if the gemstone 301 is a polished diamond or even lower for other types of gemstones. Accordingly, the exterior surface of the table 302 reflects only a portion of the collimated light that is incident thereon. Another portion of this light penetrates into the gemstone 301. Further, since the exterior surface of the table 302 is parallel to the top surface 107 of the transparent support 106, reflected light from the exterior surface of the table 302 is oriented substantially perpendicular to the top surface 107 and the bottom surface 108 of the transparent support 106.

[0047] The reflected light from the table 302 accounts for a third component 307 in the reflection response, which is schematically indicated in FIG. 3. This component will be referred to hereafter as the table-related component 307 for ease of reading. The table- related component 307 is grayish. This is mainly due to two factors. First, the reflected light from the table 302 is oriented substantially perpendicularly as discussed hereinbefore. Second, the relatively low reflectance of the table 302 makes that the table-related component 307 is grayish.

[0048] A fourth source of reflection are the facets of the gemstone 301 and, more precisely, their interior surfaces. These interior surfaces are referred to hereinafter as interior facet surfaces for ease of reading. The interior facet surfaces may reflect light that has penetrated into the gemstone 301, through the crown 304 and through the table 302, as discussed hereinbefore. These internal reflections may be multiple. That is, light that has penetrated into the gemstone 301 may successively be reflected by various interior facet surfaces. Light that has penetrated into the gemstone 301 may exit after one or more internal reflections. This gemstone-exiting light is thus marked by the facets of the gemstone 301. The gemstone-exiting light, which is marked by the facets of the gemstone 301, accounts for further components in the reflection response. These further components will be referred to as internal reflection components for ease of reading. The internal reflection components will generally make that the light reflection response 300 comprises brighter zones and darker zones defining contours within the light reflection response 300. These contours may have respective shapes and respective positions within the light reflection response 300. These respective shapes and positions depend on the facets of the gemstone 301 and, more specifically, on their geometric characteristics, as well as on their relative positions.

[0049] The light reflection response 300 from the reflection space 110 discussed hereinbefore manifests itself as light exiting the bottom surface 108 of the transparent support 106 as illustrated in FIG. 3. This light arrives at the large field-of-view camera 114 by following, at least partially, the large field-of-view optical path 122 indicated in FIG. 2. The large field-of-view telecentric lens 116 projects the light exiting the bottom surface 108 of the transparent support 106 on the large field-of-view image sensor 117. The large field-of-view image sensor 117 thus receives the light reflection response 300 from the reflection space 110 with a relatively small magnification provided by the large field-of- view telecentric lens 116.

[0050] The large field-of-view telecentric lens 116 projects the light reflection response 300 on the large field-of-view image sensor 117 without perspective effects, or at least, with no significant perspective effects. The large field-of-view image sensor 117 thus receives a faithful projection of the light reflection response 300. This allows accurate and precise measurement of features, such as, for example, contours, in the light reflection response 300 from the reflection space 110. These measurements will be discussed hereinafter, as well as use of results that these produce.

[0051] Furthermore, the large field-of-view telecentric lens 116, which has an optical axis, only passes light rays that are substantially parallel to its optical axis. This provides a filtering effect: the large field-of-view image sensor 117 will only receive components in the light exiting the bottom surface 108 of the transparent support 106 that are substantially perpendicular to this surface. This filtering effect may make that relatively few internal reflection components reach the large field-of-view image sensor 117. This, in turn, may significantly facilitate identification of features in the reflection response, as well as accurate and precise measurement of these features. The filtering effect provided by a telecentric lens, such as the large field-of- view telecentric lens 116, is gradual. The telecentric lens can be said to have a transmission efficiency that is 100% in case the light ray is perfectly parallel to its optical axis. The light ray has an angle of zero degree (0°) with respect to the optical axis of the telecentric lens in that case. The transmission efficiency decreases as the angle between the light ray and the optical axis of the telecentric lens increases.

[0052] The filtering effect provided by large field-of-view telecentric lens 116 may be within the following boundaries. On the one hand, the transmission efficiency of this lens should be at least 2% in case the angle between the light ray and its optical axis is one degree (1°). In case the transmission efficiency is lower at this angle, too few of the light reflections occurring in the reflection space 110 may reach the large field-of-view image sensor 117. The filtering effect is too strong in that case; useful details may be eliminated. On the other hand, the transmission efficiency of the large field-of-view telecentric lens 116 should be 2% at the most in case the angle between the light ray and its optical axis is five degrees (5°). In case the transmission efficiency is higher at this angle, too many of the light reflections occurring in the reflection space 110 may reach the large field-of-view image sensor 117. The filtering effect is too weak in that case; the image that is captured may comprise too many and unnecessary details.

[0053] The filtering effect provided by large field-of-view telecentric lens 116 may be sharper than that indicated in the preceding paragraph. For example, on the one hand, the transmission efficiency may be at least 2% in case the angle between the light ray and the optical axis of the large field-of-view telecentric lens 116 lens is 3 degrees (3°). On the other hand, the transmission efficiency may be 2% at the most in case the angle between the light ray and the optical axis of the large field-of-view telecentric lens 116 is four degrees (4°). Accordingly, according to these specifications, the transmission efficiency may be relatively high up to 3° and may then decrease relatively sharply from 3° to 4°. The filtering effect according to these specifications has been found to be particularly suited for capturing images of relatively small gemstones.

[0054] The filtering effect provided by large field-of-view telecentric lens 116 may be sharper in another angular range. For example, on the one hand, the transmission efficiency may be at least 2% in case the angle between the light ray and the optical axis of the large field-of-view telecentric lens 116 lens is 1 degree (1°). On the other hand, the transmission efficiency may be 2% at the most in case the angle between the light ray and the optical axis of the large field-of-view telecentric lens 116 is two degrees (2°). Accordingly, according to these specifications, the transmission efficiency may be relatively high up to 1° and may then decrease relatively sharply from 1° to 2°. The filtering effect according to these specifications has been found to be particularly suited for capturing images of relatively large gemstones.

[0055] A way of operation similar to that described hereinbefore applies to the small field-of-view light source 121 and the small field-of-view camera 115. Briefly, the small field-of-view light source 121 may equally generate a beam of collimated light. The beam of collimated light follows the small field-of-view optical path 124 to enter into the aforementioned reflection space 110. A light reflection response from the reflection space 110 manifests itself as light exiting the bottom surface 108 of the transparent support 106. The light reflection response is as discussed hereinbefore with reference to FIG. 3. It should be noted that, alternatively, the large field-of-view light source 120 may generate a beam of collimated light to illuminate the gemstone 301. The small field-of-view light source 121 may thus be dispensed with.

[0056] The light exiting the bottom surface 108 of the transparent support 106 arrives at the small field-of-view camera 115 by following, at least partially, the small field-of-view optical path 124 indicated in FIG. 2. The small field-of-view telecentric lens 118 projects this light on the small field-of-view image sensor 119. The small field-of-view image sensor 119 thus receives the light reflection response 300 from the reflection space 110 with a relatively large magnification provided by the small field-of-view telecentric lens 118.

[0057] Like the large field-of-view telecentric lens 116, the small field-of-view telecentric lens 118 does not produce a perspective effect, or at least not significantly. The small field-of-view telecentric lens 118 equally provides the filtering effect discussed hereinbefore with respect to the large field-of-view telecentric lens 116. The boundaries of this filtering effect discussed hereinbefore may thus equally apply to the small field-of- view telecentric lens 118.

[0058] The large field-of-view camera 114 and a small field-of-view camera 115 may each capture an image covering an area within their respective fields of view on the bottom surface 108 of the transparent support 106. This covered area is larger for the large field-of-view camera 114 than that for the small field-of-view camera 115. However, the image captured by the small field-of-view camera 115 may show more details, or may show details with greater precision, or both, than the image captured by the large field-of- view camera 114. For example, the image captured by the large field-of-view camera 114 may cover a relatively large area having a shortest dimension of about 15 mm. A pixel in the image may correspond to a size of 9 pm in this area. For example, the image captured by the large field-of-view camera 114 may cover an area of about 34.9 mm by 19.6 mm on the bottom surface 108 of the transparent support 106, wherein a pixel may correspond with a size of 9,1 pm. The image captured by the small field-of-view camera 115 may cover a smaller area having a shortest dimension of about 6 mm. A pixel may correspond to a size of 4 pm in this area. For example, the image captured by the small field-of-view camera 115 may cover an area of about 15.4 mm by 8.6 mm on the bottom surface 108 of the transparent support 106, wherein a pixel may correspond with a size of 4 pm. The aforementioned areas, which differ in size, may be centered with respect to each other.

[0059] An optical analysis of a gemstone 301 may be based on an image captured by the large field-of-view camera 114, or on an image captured by the small field-of-view camera 115, or on both these images. In case the gemstone 301 is relatively large, the large field-of-view light source 120 and the large field-of-view camera 114 may be used to capture an image of the gemstone 301. The small field-of-view light source 121 and the small field-of-view camera 115 may be used to capture a further image, which may cover only part of the gemstone 301, may additionally be used to obtain more details, or to obtain details with greater precision, or both, In case the gemstone 301 is relatively small, the small field-of-view light source 121 and the small field-of-view camera 115 may be used exclusively.

[0060] FIG. 4 is an exemplary image 400 of a gemstone captured in the exemplary gemstone analysis system 100. Basically, the image 400 comprises three zones: a peripheral zone 401, a ring-shaped zone 402, a center zone 403 within the ring-shaped zone 402. The peripheral zone 401 corresponds with the mirror-related component 305 in the light reflective response illustrated in FIG. 3. The peripheral zone 401 is relatively bright. That is, pixels in the peripheral zone 401 have relatively high luminance values.

[0061] The ring-shaped zone 402 in the image 400 corresponds with the crown- related component 306 in the light reflective response illustrated in FIG. 3. The ringshaped zone 402 is relatively dark. That is, a relatively large majority of pixels in the ringshaped zone 402 have relatively low luminance values.

[0062] The center zone 403 in the image 400 corresponds with the table-related component 307 in the light reflective response illustrated in FIG. 3. The center zone 403 is primarily grayish, darker than the peripheral zone 401 but brighter than the ring-shaped zone 402.

[0063] The image 400 further comprises relatively small patches 404 in the ringshaped zone 402 and in the center zone 403. Only a single patch is denoted by reference numeral 404 for the sake of simplicity and clarity. These patches 404 are formed by clusters of luminance values that are different from surrounding luminance values. In this example, the patches 404 are primarily triangularly shaped. The relatively small patches 404 correspond with the internal reflection components discussed hereinbefore. The image 400 only includes internal reflection components comprising reflected light that is perpendicularly oriented as discussed hereinbefore. This makes that the image 400 comprises relatively few patches 404 of relatively high contrast. This, in turn, facilitates optic analysis of the image 400.

[0064] The aforementioned zones 401-403 and patches 404 account define various contours in the exemplary image 400 illustrated in FIG. 4. A contour may be defined as a closed line along which a sharp luminance transition occurs in the image 400. A sharp luminance transition between the peripheral zone 401 and the ring-shaped zone 402 defines a girdle-related contour 405. A sharp luminance transition between the ring-shaped zone 402 and the center zone 403 defines a table-related contour 406. Sharp luminance transitions between the aforementioned patches 404 and its surroundings define various internal -refl ecti on-rel ated contours .

[0065] The processor 113 may identify at least some of the aforementioned contours. The processor 113 may then generate a fingerprint data set that includes morphological characteristics of at least one contour that has been identified. The morphological characteristics of a contour may include, for example, any of the following: shape, size, orientation, and position with respect to another contour. The aforementioned contours and their morphological characteristics may uniquely characterize a gemstone 301. Accordingly, a unique gemstone fingerprint may be obtained by including these characteristics in the fingerprint data set.

[0066] The exemplary gemstone analysis system 100 produces images that allow generating unique gemstone fingerprints through relatively simple processing. This is because the images are relatively easy to analyze. An image of a gemstone that is obtained as described hereinbefore comprises pronounced contours that are relatively easy to identify and that uniquely characterize the gemstone. This is apparent from the image 400 illustrated in FIG. 4 by way of example. FIG. 5 schematically illustrates an exemplary method 500 of generating a fingerprint data set uniquely characterizing a gemstone 301. FIG. 5 provides a flow chart diagram of this method 500, which comprises several steps 501-506. The method 500 is applied to an image of a gemstone produced by the exemplary gemstone analysis system 100 as described hereinbefore. This image may correspond with, for example, the image 400 illustrated in FIG. 4. This is assumed to be the case for the sake of explanation. The processor 113 in the exemplary gemstone analysis system 100 may carry out the method 500 illustrated in FIG. 5 by executing a software program. FIG. 5 may thus be regarded as a schematic representation of the software program, or at least a portion thereof. The software program may be stored in a memory within the exemplary gemstone analysis system 100.

[0067] In a first step 501, the processor 113 converts the image 400 of the gemstone into a binary map by applying a relatively high luminance threshold. This luminance threshold is relatively close to an extreme luminance value in the image 400, which may be a luminance value of a pixel in the peripheral zone 401 illustrated in FIG. 4. In case a pixel has a luminance value that is above the relatively high luminance threshold, the pixel may be mapped to a given one of two possible binary values. Conversely, in case a pixel has a luminance value that is below the aforementioned threshold, the pixel may be mapped to the other one of the two possible binary values. The processor 113 may then readily identify and extract the girdle-related contour 405 from the binary map. Namely, the girdle-related contour 405 is the largest contour in the binary map or, in an extreme case, the sole contour in the binary map. The processor 113 may then include morphological characteristics of the girdle-related contour 405 in the fingerprint data set, as well as its position.

[0068] In a second step 502, the processor 113 may crop the image 400 of the gemstone on the basis of the binary map. Accordingly, a cropped image 400 of the gemstone may be obtained, which is delimited by the girdle-related contour 405. The processor 113 converts the cropped image 400 of the gemstone into a further binary map by applying a medium luminance threshold. The medium luminance threshold may be somewhere in between the aforementioned relatively high luminance threshold and another extreme luminance value in the image 400, which may be a luminance pixel in the ringshaped zone 402. The processor 113 may then readily identify and extract the table-related contour 406 from the further binary map. Namely, the table-related contour 406 is the largest contour in the further binary map or, in an extreme case, the sole contour in this binary map. The processor 113 may then include morphological characteristics of the table-related contour 406 in the fingerprint data set, as well as its position.

[0069] In third step 503, the processor 113 may calculate a relative distance between the girdle-related contour 405 and the table-related contour 406. This relative distance may also uniquely characterize the gemstone 301 or, at least, contribute to uniquely characterizing the gemstone 301. The processor 113 may then include the relative distance in the fingerprint data set.

[0070] In a fourth step 504, the processor 113 may identify further contours in the further binary map, which are smaller than the table-related contour 406. These smaller contours are generally those of the patches 404 in the image 400, which are related to the internal reflection components as discussed hereinbefore. The smaller contours are thus representative of the internal reflections within the gemstone 301, which may also uniquely characterize the gemstone or, at least, contribute to uniquely characterizing the gemstone. The processor 113 may then include morphological characteristics of one or more of the smaller contours in the fingerprint data set, as well as their respective positions.

[0071] In fifth step 505, the processor 113 may interrogate a database of reference contours, which may include reference girdle contours and reference table contours. The processor 113 may then identify a reference girdle contour that matches with the girdle- related contour 405 in the image 400 of the gemstone. The processor 113 may then further identify a reference table contour that matches with the table-related contour 406 in the image 400 of the gemstone. The processor 113 may then include data identifying these matching reference contours in the fingerprint data set. As such, this data may not uniquely characterize the gemstone. However, the data identifying the matching reference contours may allow efficient authentication and identification of the gemstone concerned. Namely, this data may identify a category to which the gemstone belongs so that operations needed for authentication and identification may be limited to this category.

[0072] In a sixth step 506, the processor 113 may uniquely associate the fingerprint data set with an identifier that has been assigned to the gemstone. A user may specify this identifier by means of the user interface mentioned hereinbefore. The identifier may be, for example, a unique code that may have been assigned to the gemstone in accordance with, for example, a specific standard imposing a specific format for the unique code.

[0073] FIG. 6 schematically illustrates an exemplary method 600 of authenticating a gemstone. FIG. 6 provides a schematic flow chart diagram of this method 600, which comprises several steps 601-602. In the method 600, the exemplary gemstone analysis system 100 described hereinbefore with reference to FIGS. 1-5 is used. It is assumed that the gemstone to be authenticated is present on the transparent support 106 of the gemstone analysis system 100 illustrated in FIGS. 1 and 2.

[0074] In a first step 601, a user may specify an identifier that has been assigned to the gemstone. It is assumed that the identifier has previously been associated with a fingerprint data set that has previously been generated for this gemstone, as discussed hereinbefore. This fingerprint data set then constitutes a reference fingerprint data set for authenticating the gemstone that is present on the transparent support 106.

[0075] In a second step 602, the exemplary gemstone analysis system 100 generates a fingerprint data set for the gemstone that is present on the transparent support 106. This process has been described hereinbefore with reference to FIGS. 1-5.

[0076] In a third step 603, the fingerprint data set that has been generated is compared with the reference fingerprint data set. The gemstone is authenticated as genuine if the fingerprint data set that has been generated matches with the reference fingerprint data set. Correspondingly, if there is no match, the gemstone is found not to be genuine.

[0077] FIG. 7 schematically illustrates an exemplary method 700 of identifying a gemstone. FIG. 7 provides a schematic flow chart diagram of this method 700, which comprises several steps 701-702. In this method 700 too, the exemplary gemstone analysis system 100 described hereinbefore with reference to FIGS. 1-5 is used. It is again assumed that the gemstone to be identified is present on the transparent support 106 of the gemstone analysis system 100 illustrated in FIGS. 1 and 2.

[0078] In a first step 701, the exemplary gemstone analysis system 100 generates a fingerprint data set for the gemstone that is present on the transparent support 106. This process has been described hereinbefore with reference to FIGS. 1-5.

[0079] In a second step 702, a database is interrogated. This database comprises respective fingerprint data sets that have previously been associated with respective identifiers that have been assigned to respective gemstones. These respective fingerprint data sets in the database constitute respective reference fingerprint data sets. The database is searched to find a reference fingerprint data set that matches with the fingerprint data set that has been generated for the gemstone that is present on the transparent support 106. The gemstone is identified by the identifier associated with the reference fingerprint data set that matches with the fingerprint data set that has been generated. If there is no matching reference fingerprint data set, no identification is possible in this matter. Other databases may then be interrogated. FIG. 8 schematically illustrates an exemplary method 800 of identifying a particular gemstone among various gemstones FIG. 8 provides a schematic flow chart diagram of this method 800, which comprises several steps 801-804. In this method 800 too, the exemplary gemstone analysis system 100 described hereinbefore with reference to FIGS. 1-5 is used. It is assumed the various gemstones are present on the gemstone holder 102 of the gemstone analysis system 100 illustrated in FIG. 1.

[0080] In a first step 801, a user may specify an identifier that has been assigned to the particular gemstone to be identified. It is assumed that the identifier has previously been associated with a fingerprint data set that has previously been generated for this gemstone, as discussed hereinbefore. This fingerprint data set then constitutes a reference fingerprint data set for identifying the particular gemstone among various gemstones that are present on the gemstone holder 102.

[0081] In a second step 802, the pick-and-place feeder mechanism 103 may pick up a gemstone from the gemstone holder 102. The pick-and-place feeder mechanism 103 may then place the gemstone on the transparent support 106 of the gemstone analysis unit 101, as discussed hereinbefore with reference to FIGS. 1 and 2.

[0082] In a third step 803, the exemplary gemstone analysis system 100 generates a fingerprint data set for the gemstone that has been placed on the transparent support 106. This process has been described hereinbefore with reference to FIGS. 1-5.

[0083] In a fourth step 804, the exemplary gemstone analysis system 100 may determine whether the fingerprint data set that has been generated matches with the reference fingerprint data set. If there is a match, the gemstone that is present on the transparent support 106 is the particular gemstone, which was to be identified. If there is no match, the second to fourth steps 802-804 are carried out anew, whereby, in the second step 802, the pick-and-place feeder mechanism 103 picks up another gemstone from the gemstone holder 102. The third and fourth steps 803, 804 are then carried out for this other gemstone.

[0084] FIG. 9 schematically illustrates another exemplary gemstone analysis system 900. FIG. 9 provides a schematic perspective view of this other exemplary gemstone analysis system 900, which will be referred to as the second exemplary gemstone analysis system 900 for ease of reading. Correspondingly, the exemplary gemstone analysis system 100 presented hereinbefore with reference to FIGS. 1 to 8 will be referred to hereinafter as the first exemplary gemstone analysis system 100. The second exemplary gemstone analysis system 900 includes a housing 901 having a recess 902 in which a gemstone to be analyzed may be placed. Specifically, the recess 902 is comprised between a platform 903 and a fixed cap 904, which form part of the housing 901. The platform 903 comprises a transparent support 905 on which the gemstone may rest. The fixed cap 904 may comprise a light reflecting arrangement that faces the transparent support 905.

[0085] The transparent support 905 and the light reflecting arrangement of the second exemplary gemstone analysis system 900 may be similar to those of the first exemplary gemstone analysis system 100 presented hereinbefore. More generally, FIG. 2 may equally apply to the second exemplary gemstone analysis system 900, representing various components within its housing 901. The second exemplary gemstone analysis system 900 may thus operate in a manner largely similar to that described hereinbefore with respect to the first exemplary gemstone analysis system 100. A difference is that, in the second exemplary gemstone analysis system 900, an operator may place the gemstone on the transparent support 905 whereas, in the first exemplary gemstone analysis system 100, the pick-and-place feeder mechanism 103 may place the gemstone on the transparent support 106. Nevertheless, the second exemplary gemstone analysis system 900 may be equipped with a pick-and-place feeder mechanism configured to place a gemstone on the transparent support 905.

[0086] NOTES

[0087] The embodiments described hereinbefore with reference to the drawings are presented by way of illustration. The invention may be implemented in numerous different ways. In order to illustrate this, some alternatives are briefly indicated.

[0088] There are numerous different ways of implementing a gemstone analysis system in accordance with the invention. In the embodiments presented hereinbefore, a gemstone is placed on a transparent support, such as a glass plate. In other embodiments, the gemstone may be placed in a holder that need not be transparent. Such a holder may hold, for example, a jewelry item that includes a gemstone. The table of the gemstone may face upwards. The illumination arrangement may then illuminate the gemstone with collimated light coming from above, directed towards the table. Such an embodiment need not comprise a light-reflecting arrangement. A girdle identification may thus be dispensed with. However, a contour of the table may be identified, as well as internal reflections. This may be done, for example, in a manner as discussed hereinbefore. The holder may be orientable so as to align the table of the gemstone with respect to the collimated light and the camera and the telecentric lens therein. This alignment may involve a pre-aligned transparent plate against which the table of the gemstone is brought into contact. Such another embodiment as described here may have a microscope-like appearance.

[0089] Yet other embodiments may be specifically adapted for analyzing rough gemstones. These other embodiments may comprise hardware that is similar to the embodiments presented hereinbefore with reference to FIGS. 1 and 2. However, the processor may carry out operations different from those described hereinbefore with reference to FIG. 5. Briefly stated, instead of identifying a table contour and internal reflections, the processor identifies gemstone trigons in a captured image to generate the fingerprint data set. The processor may identify a peripheral contour in a manner similar to that described hereinbefore and include features of the peripheral contour in the fingerprint data set.

[0090] There are numerous different ways of implementing a telecentric lens in a gemstone analysis system in accordance with the invention. Some possible specifications have been presented concerning the filtering effect of the telecentric lens in the presented embodiments. Other embodiments may include a telecentric lens having different specifications. For example, the transmission efficiency of the telecentric lens may be characterized by any feasible combination of the following values. On the one hand, the transmission efficiency is at least 2% at 1 degree (1°), or at least 2% at 2 degrees (2°), or at least 2% at 3 degrees (3°), or at least 2% at 4 degrees (4°). On the other hand, the transmission efficiency is at most 2% at 1 degree (1°), or at most 2% at 2 degrees (2°), or at most 2% at 3 degrees (3°), or at most 2% at 4 degrees (4°), or at most 2% at 5 degrees (5°).

[0091] There are numerous different ways of implementing a processor in a gemstone analysis system in accordance with the invention. As indicated hereinbefore, the processor may be external to a gemstone analysis device that includes the illumination arrangement and the camera of the gemstone analysis system. The term processor should be interpreted broadly. This term encompasses any data-processing device or set of data- processing devices that may generate a fingerprint data set based on an image produced by an image sensor in the camera of the gemstone analysis device. For example, the processor may comprise a server that is communicatively coupled with the gemstone analysis device. The processor may further comprise a data processing device, such as, for example, a personal computer, which is located nearby the gemstone analysis device. This local data processing device may operate as an intermediate between the server and the gemstone analysis device and may also operate as a controller of the gemstone analysis device. The remarks made hereinbefore demonstrate that the embodiments described with reference to the drawings illustrate the invention, rather than limit the invention. The invention can be implemented in numerous alternative ways that are within the scope of the appended claims. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope. Any reference sign in a claim should not be construed as limiting the claim. The verb “comprise” in a claim does not exclude the presence of other elements or other steps than those listed in the claim. The same applies to similar verbs such as “include” and “contain”. The mention of an element in singular in a claim pertaining to a product, does not exclude that the product may comprise a plurality of such elements. Likewise, the mention of a step in singular in a claim pertaining to a method does not exclude that the method may comprise a plurality of such steps. The mere fact that respective dependent claims define respective additional features, does not exclude combinations of additional features other than those reflected in the claims.

Claims

CLAIMS:

1. A gemstone analysis system (100) capable of optically analyzing a gemstone (301) to generate a fingerprint data set uniquely characterizing the gemstone, the gemstone analysis system comprising: an illumination arrangement (112) configured to illuminate the gemstone with collimated light only to obtain a reflection (300) from the gemstone that results from the collimated light only; a camera (114) comprising a telecentric lens (116) and an image sensor (117), the camera being arranged to exclusively receive reflections that result from the collimated light including the reflection from the gemstone, whereby the reflections traverse the telecentric lens to arrive at the image sensor; the telecentric lens having an optical axis and a transmission efficiency for a light ray traversing the telecentric lens that decreases as an angle between the light ray and the optical axis increases, the transmission efficiency being, on the one hand, at least 2% with respect to that for zero angle in case the angle is 1° and, on the other hand, 2% at the most in case the angle is 5°; and a processor (113) configured to generate the fingerprint data set based on an image (400) produced by the image sensor in response to the reflections that have traversed the telecentric lens.

2. A gemstone analysis system according to claim 1, comprising: a transparent support (106) on which the gemstone (301) to be analyzed can be placed so that the gemstone is in contact with a top surface (107) of the transparent support, and wherein: the illumination arrangement (112) is configured to make the collimated light incident on a bottom surface (108) of the transparent support, with the collimated light exiting the top surface perpendicularly thereto.

3. A gemstone analysis system according to claim 2 comprising:a light-reflecting arrangement (109) facing the top surface (107) of the transparent support (106) and being parallel thereto.

4. A gemstone analysis system according to any of claims 2 and 3, comprising: another camera (115) equally comprising a telecentric lens (118) and an image sensor (119), the other camera equally being arranged to exclusively receive reflections that result from the collimated light including the reflection (300) from the gemstone, whereby the reflections traverse the telecentric lens to arrive at the image sensor, the telecentric lens of the other camera equally having an optical axis and a transmission efficiency for a light ray traversing the telecentric lens that decreases as an angle between the light ray and the optical axis increases, the transmission efficiency being, on the one hand, at least 2% with respect to that for zero angle in case the angle is 1° and, on the other hand, 2% at the most in case the angle is 5°, wherein the telecentric lens (116) of the camera and the telecentric lens (118) of the other camera have different magnifications.

5. A gemstone analysis system according to claim 4, wherein the camera (114) has a field-of-view covering a first area on the bottom surface (108) of the transparent support (106) and the other camera (115) has another field-of-view covering a second area on the bottom surface of the transparent support, the first area and the second area differing in size but being centered with respect to each other.

6. A gemstone analysis system according to any of claims 2 to 5, wherein the transparent support (106) comprises a glass plate.

7. A gemstone analysis system according to any of claims 2 to 6, wherein the transparent support (106) comprises an anti -reflective coating.

8. A gemstone analysis system according to any of claims 2 to 7, wherein: the illumination arrangement (112) comprises: a light source (120) configured to generate the collimated light; and an optical path (122) extending between the light source and the bottom surface (108) of the transparent support (106); andthe camera (114) is arranged to receive the light exiting the bottom surface of the transparent support at least partially through the optical path.

9. A gemstone analysis system according to claim 8, wherein the optical path (122) includes a light-deflecting arrangement (123) configured to receive the collimated light from the light source (120) along a first axis and to deflect the collimated light along a second axis toward the bottom surface (108) of the transparent support (106).

10. A gemstone analysis system according to claim 9, wherein the first axis and the second axis are perpendicular with respect to each other.

11. A gemstone analysis system according to any of claims 2 to 10, wherein the processor (113) is configured to identify a girdle-related contour (405) in the image (400) produced by the image sensor (117) of the camera (114), the girdle-related contour being the largest contour that has been identified in the image.

12. A gemstone analysis system according to claim 11, wherein the processor (113) is configured to identify a table-related contour (406) in the image (400) produced by the image sensor (117) of the camera (114), the table-related contour being the largest contour that has been identified within the girdle-related contour (405).

13. A gemstone analysis system according to claim 12, wherein the processor (113) is configured to identify the girdle-related contour (405) by applying a first luminance threshold to the image (400), and to identify the table-related contour (406) by applying a second luminance threshold to the image, the second luminance threshold being different from the first luminance threshold.

14. A gemstone analysis system according to claim 13, wherein the first luminance threshold is closer to an extreme luminance value in the image than the second luminance threshold.

15. A gemstone analysis system according to any of claims 12 to 14, wherein the processor (113) is configured to determine a relative distance between the girdle-related contour (405) and the table-related contour (406), the relatively distance being included in the fingerprint data set.

16. A gemstone analysis system according to any of claims 12 to 15, wherein the processor (113) is configured to identify intemal-reflection-related contours in the image (400) produced by the image sensor of the camera, the internal-reflection-related contours being contours within the girdle-related contour (405) that are smaller than the table-related contour (406).

17. A gemstone analysis system according to claim 16, wherein the processor (113) is configured to include in the fingerprint data set, morphological characteristics of at least one of the following contours: the girdle-related contour (405), the table-related contour (406), and at least one internal-reflection-related contour.

18. A gemstone analysis system according to any of claims 11 to 17, wherein the processor (113) is configured to interrogate a database of reference contours so as to identify a reference contour in the database that matches with at least one contour that has been identified in the image, whereby a data identifying the reference contour is included in the fingerprint data set.

19. A gemstone analysis system according to any of claims 1 to 18, wherein the processor (113) is configured to uniquely associate the fingerprint data set with an identifier that has been assigned to the gemstone (301).

20. A gemstone analysis system according to any of claims 1 to 19, comprising a gemstone holder (102) configured to hold multiple gemstones; and a feeder (103) configured to pick up the gemstone (301) to be analyzed from the gemstone holder and to place the gemstone on a support positioned so that the gemstone placed thereon is illuminated with the collimated light only and the reflection from the gemstone, which results from the collimated light only, is received by the camera (H4).

21. Use of a gemstone analysis system according to any of claims 1 to 20 for generating fingerprint data set uniquely characterizing a gemstone.

22. A gemstone analysis device for use in a gemstone analysis system (100) according to any of claims 1 to 20, the gemstone analysis device comprising the illumination arrangement (112), the camera (114), and a communication interface adapted to transmit the image (400) produced by the image sensor (117) of the camera to the processor (113), which is external to the gemstone analysis device.

23. A method of authenticating a gemstone, the method comprising: specifying an identifier that has been assigned to the gemstone, the identifier being associated with a reference fingerprint data set that has previously been generated for the gemstone; using a gemstone analysis system (100) according to any of claims 1 to 18 to generate the fingerprint data set uniquely characterizing the gemstone; and authenticating the gemstone as genuine if the fingerprint data set matches with the reference fingerprint data set.

24. A method of identifying a gemstone, the method comprising: using a gemstone analysis system (100) according to claim 19 to generate the fingerprint data set uniquely characterizing the gemstone; interrogating a database comprising respective reference fingerprint data sets associated with respective identifiers that have been assigned to respective gemstones; identifying a reference fingerprint data set in the database that matches with the fingerprint data set that has been generated, the identifier associated with the reference fingerprint data set identifying the gemstone.

25. A method of identifying a particular gemstone among various gemstones, the method comprising: specifying an identifier that has been assigned to the particular gemstone, the identifier being associated with a reference fingerprint data set that has previously been generated for the gemstone; selecting a gemstone among the various gemstones; using a gemstone analysis system (100) according to any of claims 1 to 18 to generate the fingerprint data set uniquely characterizing the gemstone that has been selected;identifying the gemstone that has been selected as the particular gemstone if the fingerprint data set matches with the reference fingerprint data set; and if there is no match, selecting another gemstone among the various gemstones and continue using the gemstone analysis system for identifying the particular gemstone.

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