CLAIMS:
1. A method for producing an accurate 3D-Model of a gemstone, said method
comprising:
a) obtaining an original 3D-model of an external surface of said gemstone
including facets, edges abounding said facets, and junctions each constituting an
area of meeting of at least three said edges associated with at least two facets;
b) imaging at least one selected junction with only portions of its associated facets and edges disposed adjacent the junction, the location of said junction being determined based on information obtained at least partially by using the original 3D model, said imaging being performed under at least one imaging condition different from that at which the original 3-D model was obtained, and under illumination conditions providing such contrast between adjacent facets as to allow to distinguish an edge therebetween;
c) analyzing results of said imaging to obtain information regarding details of the gemstone at saidjunction; and
d) using the information obtained in step c) for producing an accurate 3D-model of said external surface of the gemstone, which is more accurate than the original 3-D model.
2. A method according to Claim 1, wherein the gemstone has a planned cut geometry
and wherein the original 3D-model of the external surface of said gemstone
comprises revealed edges and revealed junctions, and step (a) further includes
selecting said at least one selected junction in at least one of the following manners:
e) considering at least one of the revealed junctions to be said selected junction; and
f) determining at least one non-revealed junction existing in said planned cut geometry but absent from said 3D model, considering a predicted location of said non-revealed junction to be said selected junction.
3. A method according to Claim 1 or 2, wherein said gemstone is a cut gemstone
having a girdle with planned girdle features, which are features that the girdle was
planned to have when it was cut, the method further comprising the following steps:

g) obtaining one or more images of at least one selected portion of said girdle, said one or more images being taken under such conditions as to enable distinguishing at least one of said planned features at said selected portion of the girdle;
h) analyzing said one or more images to obtain information regarding details of the girdle at said selected portion thereof; and
i) using said information when producing said accurate 3D-model.
A method according to Claim 2 or Claim 3 when dependent on Claim 2, further comprising predicting a new junction absent from the original 3D model and from the planned cut geometry, based on the information obtained in at least one of steps (c) and (h), considering said new junction to be a selected junction and performing said steps (b) to (d) with respect thereto.
A method according to Claim 4, wherein when a new edge is determined which is absent from the original 3D model, said predicting is performed by associating said new junction with a predicted end of the new edge at its predicted intersection with an edge revealed in said original 3D model.
A method according to any one of Claims 2 to 5, wherein when based on the information obtained in at least one of steps (c) and (h), it is realized that at least one revealed edge is missing from any image of its associated junction, such missing edge is not included in the accurate model in said steps (d) and (i). A method according to any one of Claims 3 to 5 or Claim 6, when dependent on Claim 3, wherein step (g) is performed under such conditions as to distinguish at least one edge meeting with the girdle, and if said images include such edge and/or a junction associated with the girdle at which such edge terminates, such edge and/or such junction constituting said details in step (c).
A method according to any one of the preceding claims, wherein the at least one imaging condition in step (b) is at least one of the magnification and resolution, which is higher than that at which the original 3-D model was obtained. A method according to any one of the preceding claims, wherein the at least one imaging condition in step (b) is a depth of focus which is lower than that at which the original 3-D model was obtained.

10. A method according to any one of the preceding claims, wherein the step (a)
comprises
1) illuminating the gemstone by means of one or more step-(a) illumination device,
m) imaging the gemstone by means of a step-(a) imaging device, and
n) rotating the gemstone relative to the step-(a) illumination device and step-(a) imaging device to obtain a plurality of images, based on which said original 3D model is calculated; and
o) wherein obtaining said one or more images in said step (b) includes illuminating the gemstone by means of one or more step-(b) illumination devices, and imaging the gemstone so illuminated by means of a step-(b) imaging device, and wherein at least one of the following conditions is fulfilled:
i) at least one of said step-(b) illumination devices provides illumination different from that of said step-(a) illumination device, and
ii) said step-(b) imaging device is different from said step-(a) imaging device.
11. A method according to any one of Claims 1 to 10, wherein said gemstone is supported by a gemstone stage station including a gemstone holder with a gemstone supporting surface, and a stage with a holder mounting surface whose center has a disposition which is invariant relative to a first optical axis FOA of an imaging device used in step (a) for gemstones of any size which the system is configured to examine, and the distance from which to the gemstone supporting surface is variable depending on the size of the gemstone, so that in a relative Cartesian coordinate system (RCCS) said first optical axis FOA is defined by the Y - axis of the RCCS and said distance is variable along the Z axis, which optionally constitutes an axis of rotation of the gemstone holder relative to said imaging device and/or to an imaging device used in step (b).
12. A method according to Claim 11, wherein said gemstone is illuminated by means of one or more step-(b) illumination devices with such an illumination that at least three adjacent facets of the crown or the pavilion, or two facets of the crown or the pavilion and the girdle, are each at least partially illuminated with such a contrast between at least one couple of their adjacent illuminated surfaces as to enable distinguishing an edge therebetween.

13. A method according to Claim 12, wherein said contrast is obtained by at least one of
the following:
p) said illumination is uniformly diffusive along the entire field of vision of an imaging system used in step (b);
q) said illumination has a chief ray with an angle of incidence selected based on an average between angles defined by said at least three facets or two facets and the girdle, with said axis Z;
r) said illumination is provided by an illumination source using contrast improving techniques optionally comprising a mask interacting differently with light exiting from said illumination source at different surface portions of said mask, including at least one of the following:
iii) at least two surface portions with distinct absorption properties,
iv) at least two surface portions with different polarization properties, and
v) at least two surface portions that provide different propagation properties of the light.
14. A method according to Claim 13, wherein the number of said surface portions corresponds to the number of facets in the field of vision.
15. A method according to any one of Claims 12 to 14, wherein the gemstone is illuminated with an upper illumination device disposed on the opposite side of the X-Y plane as the stage, optionally with a chief ray forming an acute angle to said Z-axis.
16. A method according to Claim 15, wherein said upper illumination device is movable along the Z-axis of said RCCS to change its distance from the X-Y plane and thereby obtain uniformly diffusive illumination.
17. A method according to any one of Claim 12 to 16, wherein the gemstone is illuminated with a lower illumination device disposed on the same side of the X-Y plane as the stage, optionally at a constant distance from said plane.
18. A method according to any one of Claims 12 to 17, wherein said step (b) is performed without moving the gemstone relative to the gemstone supporting surface after having performed said step (a).

19. A method according to any one of Claims 11 to 18, wherein the gemstone has a resting surface in contact with said gemstone supporting surface, and said supporting surface has such dimensions as to allow adjacent portion of the gemstone to radially project therefrom, and wherein optionally, the resting surface of the gemstone is at least the majority of its table, and the projecting portion is at least its crown and, possibly, an area of the table adjacent thereto.
20. A method according to any one of Claims 11 to 19, further including providing a relative translation between the gemstone supporting surface and an imaging device used in step (b) in at least one of a direction along the Z- axis and a direction along a normal to the Z- axis.
21. A method according to any one of the preceding claims, wherein said step (b) comprises obtaining a plurality of images of the or each selected junction and selecting thereamongst at least one selected image, in which one or more edges seen therein are distinguished better than in other images.
22. A method according to Claim 2 and any one of claims 3 to 2 1 when dependent on Claim 2 directly or indirectly, wherein the steps (b) to (d) are performed for all junctions revealed in step (e), and for all non-revealed junctions determined in step
(f), and optionally, wherein if said gemstone has a girdle of a planned girdle geometry including a plurality of planned girdle features, the method further comprises the following steps for all portions of the girdle: j) obtaining one or more images of at least one selected portion of said girdle, said
one or more images being taken under such conditions as to enable
distinguishing at least one of said planned features at said selected portion of the
girdle; k) analyzing said one or more images to obtain information regarding details of the
girdle at said selected portion thereof; and 1) using said information in obtaining said accurate 3D-model,
and, optionally,
m) predicting a new girdle feature absent from the original 3D model and from the planned girdle geometry, based on the information obtained in step (h), identifying a portion of the girdle comprising said new girdle feature and

performing steps (g) to (i) with respect to this portion of the girdle constituting said selected portion.
23. A method according to any one of the preceding claims, wherein in said step (b) all distinguishable edges are selected; in step (c) each selected edge constitutes said details, and in step (d) all the details determined in step (c) are included in said accurate 3D-model.
24. A method according to any one of Claims 11 to 23, further comprising centering said gemstone on said gemstone supporting surface, optionally before said step (a).
25. A system for automatically producing an accurate 3D-Model of a gemstone, the system comprising:
3D modeling system configured for obtaining an original 3D model of an external surface of a gemstone, including facets, edges abounding said facets, and junctions each constituting an area of meeting of at least three said edges associated with at least two facets;
an illumination and imaging system configured for imaging at least one junction selected from the junctions in said 3D model, with only portions of its associated facets and edges disposed adjacent the junction, under at least one imaging condition different from that at which the original 3D model was obtained, and under illumination conditions providing such contrast between adjacent facets as to allow to distinguish an edge therebetween; and
a computing system configured to operate the system for automatically producing an accurate 3D model in accordance with the method of any one of Claims 1 to 24.
26. A system according to Claim 25, comprising a stage station with a holder and holder
mounting surface; a step-(a) illumination and imaging devices for performing the
step (a) of said method, said devices constituting a part of said 3D modeling system
and having a first optical axis FOA congruent with the Y axis of a relative Cartesian
coordinate system (RCCS), the X-Y plane separating between a gemstone side and a
stage side of the system along the Z axis; and step- (b) illumination and imaging
devices, each constituting a part of said illumination and imaging system, for
performing the step-(b) of said method, wherein at least one of the step (b)
illumination devices is different from that of step (a).

27. A system according to Claim 26, including a relative movement arrangement configured for providing at least one of the following movements between the stage station and the step-(b) imaging system: translation to change a distance therebetween along the Z-axis; translation to change a distance therebetween in at least one direction perpendicular to the Z-axis, a rotation displacement to rotate at least the holder around the Z-axis, and, optionally, a rotation displacement to change an angle between the Z-axis and an optical axis of the imaging system.
28. A system according to Claim 26 or 27, wherein the step-(b) illumination devices comprise at least two step-(b) illumination devices configured to provide illumination in the form of a diffused illumination beam of an opening angle a, propagating in a propagation direction along its chief ray, each one of said at least two step-(b) illumination devices meeting one of the following conditions different from that met by at least one other of said step-(b) illumination devices:
s) it is disposed on the gemstone side of the system, is spaced from the X-Y plane to a variable distance along Z axis, so that the chief ray of said diffused illumination beam forms an acute angle with said Z direction;
t) it is disposed on the stage side of the system, is spaced from the X-Y plane to a constant distance along Z axis, so as to illuminate mainly an area disposed between the Z - axis and said step-(b) imaging device; and
u) it is spaced radially from the Z axis on the stage side or gemstone side of the system, its propagation direction has at least a vector component perpendicular to the Z - axis, and the spatial relationship between the device and said step-(b) imaging system is constant.
29. A system according to Claim 26, wherein the illumination device meeting the condition (s) or (t) is fitted with a mask configured to influence illumination therefrom so as to provide non-uniform distribution of light.
30. A system according to Claim 29, wherein the illumination device comprises an illumination source, and said mask interacts differently, at different surface portions of the mask, with light exiting from said illumination source, said mask including at least one of the following:
v) at least two surface portions with distinct absorption properties,
w) at least two surface portions with different polarization properties, and

x) at least two surface portions that provide different propagation properties of the light.
31. A system according to Claim 30, wherein said mask comprises a number of said surface portions corresponding to the number of facets of the gemstone in the field of vision.
32. A system according to any one of Claims 26 to 31, wherein the holder is selected from a set of at least two holders of different dimensions configured to support gemstones from at least two size groups by way of a support surface such that the distance between each respective support surface and the holder mounting surface of the stage station is such that the respective gemstone of each size group is placed within the field of vision of said step-(a) imaging device, and optionally the support surface coincides with said Y-axis.
33. A system according to any one of Claims 27 to 32, wherein the step-(b) imaging device is configured for taking images with at least one of a magnification, resolution or depth of focus, being different than that provided by the step-(a) imaging device.
34. A system according to Claim 33, wherein the step-(b) imaging device is configured for taking images with at least one of the following:
a magnification higher than that provided by the step-(a) imaging device;a resolution higher than that provided by the step-(a) imaging device; and
a depth of focus lower than that provided by the step-(a) imaging device.
35. A system according to any one of Claims 25 to 34, further comprising a processor with a capability for image analysis allowing it to choose out of a plurality of images at least one selected image, in which one or more edges are distinguished better than in other images.
36. A system according to any one of Claims 27 to 35, further comprising a processor configured for controlling the system to perform the following steps with respect to each selected surface portion on the gemstone:
y) causing relative movement between said stage and said step - (b) imaging device to bring said selected surface portion of the gemstone into a field of view of said step - (b) imaging device;
z) operating said step-(b) imaging device to focus on said selected surface portion;

aa) operating the step-(b) illumination system for illuminating said selected surface portion from a suitable direction, for producing conditions to distinguish a detail in said at least one image.
37. A system according to any one of Claims 28 to 36, wherein said processor is further
configured for operating the system after a gemstone has been mounted on said
gemstone supporting surface, as follows:
bb) causing said step-(b) imaging device to record a plurality of images of said selected surface portion of the gemstone at a corresponding plurality of relative positions of said stage and said step-(b) illumination devices, said images differing in the illumination conditions for distinguishing of said detail,
cc) comparing said images, deciding if at least one of the images offers said conditions for distinguishing said detail, and
vi) if in the affirmative, selecting said one of the images a selected image; and
vii) if in the negative, repeating said steps (bb), (cc) until at least one image is selected as being said selected image.
38. A system according to claim 35, wherein said processor is further configured for performing the method of any one of Claims 1 to 24.
39. A system according to any one of Claims 27 to 38, comprising a centering mechanism configured for centering said gemstone on said gemstone mounting surface.
40. A system according to Claim 39, when dependent on Claim 28, wherein said centering mechanism is configured for allowing for direct lines of sight from any illumination device to an area disposed between said gemstone supporting surface and projection of the imaging system on the X-Y plane, at least while taking said images.
41. A method of upgrading a first system configured for obtaining an original 3D model of an external surface of a gemstone, in order to provide a second system for producing a more accurate 3D model of said external surface of the gemstone than the original 3D model; said method comprising the steps of:
dd) adding to said first system a second illumination system and a second imaging device configured for imaging at least one junction with only adjacent portions

of its associated facets and edges, the location of said junction being determined based on information obtained at least from the original 3D model, said imaging being performed with at least one imaging condition being different from that or those at which the original 3-D model was obtained, and under illumination conditions providing such contrast between adjacent facets as allow to distinguish an edge therebetween; and
ee) adding computing capability for:
viii) analyzing said images to obtain information regarding details of the cut gemstone;
ix) using said information for obtaining said more accurate 3D-model of the gemstone.
42. A method according to Claim 41, wherein said imaging condition is at least one of
the following:
a magnification higher than that provided by provided by an imaging device with which the original 3D image has been obtained;
a resolution higher than that provided by provided the imaging device with which the original 3D image has been obtained; and
a depth of focus lower than that provided by the imaging device with which the original 3D image has been obtained.
43. A method according to Claim 42, wherein the first system comprises at least one first gemstone holder with a first gemstone mounting surface for mounting a gemstone thereon, said first holder being configured to be mounted on said stage base, and wherein said method further comprises replacing said at least one first holder with at least one second holder having a second gemstone supporting surface so as to allow an access of an illumination source to a space between said second gemstone supporting surface and the stage base.
44. A method according to any one of Claims 4 1 to 43, wherein the second illumination system is configured for producing a light beam producing an illumination that is uniformly diffusive along the entire field of vision of said second imaging device.
45. A method according to any one of Claims 4 1 to 44, wherein said second system is configured for performing the method according to any one of Claims 1 to 25.

46. A method according to any one of claims 4 1 to 45, wherein said second system is characterized by features according to any one of Claims 25 to 40.
47. A kit for upgrading a first system configured for obtaining an original 3D model of an external surface of a gemstone, in order to obtain a second system for producing a 3D model of said external surface of a gemstone which is more accurate than the original 3D model, said first system comprising a first set of gemstone holders each having a first gemstone mounting surface, a first illumination source and a first imaging device, and a computer system configured to produce said original 3D model, said kit comprising:
a second illumination source different from the first illumination device;- a second imaging system different from the first imaging system, configured for imaging at least one selected junction with only portions of its associated facets and edges disposed adjacent the junction, the location of said junction being determined based on information obtained at least partially by using the original 3D model, said imaging being performed under at least one imaging condition different from that at which the original 3-D model was obtained, and under illumination conditions provided by said second illumination system, with such contrast between adjacent facets as to allow to distinguish an edge therebetween;
- a capability provided to said computer system, of analyzing results of said imaging to obtain information regarding details of the gemstone at said junction; and using said information for producing the 3D-model, which is more accurate than the original 3-D model; and, optionally,
a second set of gemstone holders each having a second gemstone mounting surface and being configured for mounting on a stage base such so as to allow an access of said second illumination source to a space between said second gemstone mounting surface and the stage base.
48. A kit according to Claim 47, configured for use in a method according to any one of
Claims 4 1 to 46.