Methods, apparatus, and systems for evaluating gemstones

• US 7,336,347 B2
• Filed: 12/20/2004
• Issued: 02/26/2008
• 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:
  US11/018,042
• Publication Number:
  US 20050190356A1
• Time in Patent Office: 1,163 Days
• Field of Search: 356/30, 702/35
• 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, specifically methods which trace rays through a computer representation of a gemstone wherein the rays enter the gemstone though the gemstone crown and allow a grade to be assigned to the gemstone represented based on the ray paths through the representation.

Claims

1. A method, comprising:

providing a computer file comprising information about cut proportions of a gemstone;

tracing paths of rays through the gemstone using the computer file, wherein the rays enter the gemstone through the gemstone crown;

determining an intersection of each ray path with the gemstone crown;

determining an intersection of each ray path exiting the gemstone with a reference surface; and

assigning a grade to the gemstone based on the ray paths.

2. The method of claim 1, wherein providing the computer file comprises creating the computer file.

3. The method of claim 1, wherein the computer file is in STL format, DXF format, or IGES format.

4. The method of claim 1, wherein the ray paths are traced using an algorithm executed by a computer.

5. The method of claim 4, wherein the algorithm accounts for Snell'"'"'s law of refraction for each ray.

6. The method of claim 4, wherein the algorithm accounts for the law of reflection for each ray.

7. The method of claim 4, wherein the algorithm accounts for Fresnel reflections for each ray.

8. The method of claim 1, wherein the rays originate from in front of the gemstone'"'"'s crown.

9. The method of claim 1, wherein the rays originate from a side of the gemstone'"'"'s crown.

10. The method of claim 1, wherein the grade is assigned based on the rays intersection with the crown.

11. The method of claim 1, wherein the grade is assigned based on the rays intersection with the reference surface.

12. The method of claim 1, wherein the grade is assigned based on the proportion of rays that intersect a portion of the reference surface.

13. The method of claim 1, wherein the grade is assigned based on directions of the rays.

14. The method of claim 1, wherein rays are traced for different wavelengths.

15. The method of claim 14, wherein rays are traced for different wavelengths that originate from the same point in the same direction.

16. The method of claim 15, wherein the grade is assigned based on a divergence between rays traced for different wavelengths that originate from the same point in the same direction.

17. The method of claim 1, wherein the rays are traced for more than one orientation of the gemstone with respect to the reference surface.

18. The method of claim 1, further comprising retracing the rays from the reference surface to their point of origin.

19. The method of claim 1, further comprising compiling an image of the gemstone from the traced rays.