Methods, apparatus, and systems for evaluating gemstones

• US 7,382,445 B2
• Filed: 12/20/2004
• Issued: 06/03/2008
• Est. Priority Date: 12/22/2003
• Status: Active Grant

• Current Assignee: Gemological Institute of America Incorporated
• Original Assignee: American GEM Society
• Inventors: Sasian, Jose, Yantzer, Peter, Caudill, James
• Primary Examiner(s): Lauchman; Layla G.
• Application Number:
  US11/018,743
• Publication Number:
  US 20050190357A1
• Time in Patent Office: 1,261 Days
• Field of Search: 356/30, 356/31
• US Class Current: 356/30
• CPC Class Codes: G01N 21/00 Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light G01N3/00 - G01N19/00 take precedence
• CPC Class Codes: G01N 21/01 Arrangements or apparatus for facilitating the optical investigation
• CPC Class Codes: G01N 21/87 Investigating jewels G01N21/88 takes precedence
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features

Abstract

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

Claims

1. A method for evaluating a gemstone, the method comprising:

tracing a plurality of ray paths through a representation of a gemstone;

determining a ray direction that each of said ray paths leaves said gemstone;

providing an image of said gemstone comprising different representations, wherein each of said representations corresponds to a different range of ray directions; and

evaluating the gemstone based on the representations.

2. The method of claim 1 wherein in said using, said plurality of ray paths initiate from a single point.

3. The method of claim 2 wherein said point is located at a point above a crown of said gemstone.

4. The method of claim 1 wherein said different representations comprise different colors.

5. The method of claim 4, wherein a first color in said image corresponds to light directed by said gemstone to an observation location within a first range of polar ray directions with respect to a hemispherical reference flame centered on said representation of said gemstone.

6. The method of claim 5 wherein a second color in said image corresponds to light directed by said gemstone to an observation location within a second range of polar ray directions with respect to said hemispherical reference frame.

7. The method of claim 6 wherein a third color in said image corresponds to light directed by said gemstone to an observation location within a third range of polar ray directions with respect to said hemispherical reference frame.

8. The method of claim 7, wherein said observation location within said third range of polar ray angles corresponds to a location between about 20 centimeters and about 10 meters from said gemstone.

9. The method of claim 8, wherein said observation location within said second range of polar ray angles corresponds to a location between about 20 centimeters and about 10 meters from said gemstone.

10. The method of claim 9 wherein said observation location within said second range of polar ray angles and said observation location within said third range of polar angles corresponds to a location between about 20 centimeters and about 30 centimeters from said gemstone.

11. The method of claim 5, wherein said observation location within said first range of polar ray angles corresponds to a location between about 20 centimeters and about 30 centimeters from said gemstone.

12. The method of claim 1 wherein said tracing, determining and providing is performed by a computer.

13. The method of claim 12 wherein said evaluating is performed by a computer.

14. The method of claim 1 wherein each of said ray paths is initiated at a point outside said representation of said gemstone.

15. The method of claim 1, wherein said evaluating comprises assigning a grade by:

determining values corresponding to multiple characteristics of the gemstone;

assigning an initial grade based on said characteristics; and

deducting from said initial grade based on the relative proportions of said colors in said image.

16. The method of claim 15, wherein a first color in said image corresponds to light directed by said gemstone to an observation location within a first range of polar ray directions with respect to a hemispherical reference flame centered on said representation of said gemstone.

17. The method of claim 16 wherein a second color in said image corresponds to light directed by said gemstone to an observation location within a second range of polar ray directions with respect to said hemispherical reference frame.

18. The method of claim 17 wherein a third color in said image corresponds to light directed by said gemstone to an observation location within a third range of polar ray directions with respect to said hemispherical reference frame.

19. The method of claim 18 wherein said second range of polar direction is from 45°

to 75°

with respect to said hemispherical reference frame and said third range of polar directions is 75°

or more with respect to a hemispherical reference frame.

20. The method of claim 15, wherein said multiple characrerisrics correspond to a cut of said gemstone.

21. The method of claim 1, wherein said evaluating comprises assigning a grade by:

determining values corresponding to multiple characteristics of the gemstone;

assigning an initial grade based on said characteristics; and

deducting fiom said initial grade based on the distribution of said colors in said image.

22. The method of claim 1, wherein the gemstone is a diamond.

23. The method of claim 1 wherein said image shows the crown of said gemstone.

24. A computer system for providing an image representative of the quality of a gemstone, the system comprising:

means for tracing a plurality of ray paths through a representation of a gemstone;

means for determining a ray direction that each of said ray paths leaves said gemstone; and

means for providing an image of said gemstone comprising different colors, wherein each of said colors corresponds to a different range of ray directions.

25. A computer-readable memory storing computer-executable instructions for providing an image representative of the quality of a gemstone, the memory comprising:

computer-executable instructions for tracing a plurality of ray paths through a representation of a gemstone;

computer-executable instructions for determining a ray direction that each of said ray paths leaves said gemstone; and

computer-executable instructions for providing an image of said gemstone comprising different colors, wherein each of said colors corresponds to a different range of ray directions.