Claims
- 1. A method for changing the color of a colored Type II natural diamond comprising:
(a) placing a colored Type II natural diamond in a pressure-transmitting medium; (b) consolidating said pressure-transmitting medium into a pill; (c) exposing said pill to elevated pressure and elevated temperature for a time sufficient to change the color of the diamond; and (d) recovering said diamond.
- 2. The method of claim 1, wherein said elevated pressure ranges from about 10 to about 200 kilobars and said elevated temperature ranges from about 1500° C. to about 3500° C.
- 3. The method of claim 2, wherein said pressure ranges from about 20 to about 80 kilobars.
- 4. The method of claim 2, wherein said pressure ranges from about 50 to about 90 kilobars.
- 5. The method of claim 2, wherein said temperature ranges from about 1800° C. to about 2700° C.
- 6. The method of claim 2, wherein said pressure ranges from about 50 to about 70 kilobars and said temperature ranges from about 2200° C. to about 2700° C.
- 7. The method of claim 2, wherein said pressure ranges from about 70 to about 90 kilobars and said temperature ranges from about 1800° C. to about 2500° C.
- 8. The method of claim 1, wherein the pill is exposed to elevated pressure and elevated temperature in the graphite-stable range of the carbon-phase diagram for a time sufficient to change the color of the diamond without significant graphitization of the diamond.
- 9. The method of claim 1, wherein the pill is exposed to elevated pressure and elevated temperature above the diamond-graphite equilibrium and within the diamond-stable range of the carbon-phase diagram.
- 10. The method of claim 1, wherein said colored Type II natural diamond is a Type IIa or Type IIb diamond.
- 11. The method of claim 1, wherein the recovered diamond is colorless.
- 12. The method of claim 1, wherein the recovered diamond is a fancy-colored diamond
- 13. The method of claim 1, wherein said recovered diamond is subjected to steps (a), (b), (c) and (d) a plurality of times.
- 14. The method of claim 1, wherein said pressure-transmitting medium is thermally and chemically stable at elevated-pressure and elevated-temperature conditions and is selected from the group consisting of a salt, a carbide, a nitride, a boride, an oxide, graphite, and combinations thereof.
- 15. The method of claim 14, wherein said pressure-transmitting medium is selected from the group consisting of sodium chloride, sodium iodide, sodium bromide, potassium chloride, potassium iodide, potassium bromide, calcium chloride, calcium iodide, calcium bromide; boron nitride and boron carbide.
- 16. The method of claim 14, wherein said pressure-transmitting medium is selected from the group consisting of magnesium oxide, calcium oxide, and mixtures thereof.
- 17. The method of claim 14, wherein said pressure-transmitting medium is graphite.
- 18. The method of claim 1, wherein said pressure-transmitting medium is a finely divided powder.
- 19. The method of claim 1, wherein the consolidation step comprises melting and solidifying the pressure-transmitting medium to form the pill.
- 20. The method of claim 1, wherein said elevated temperature and said elevated pressure are maintained from 30 seconds to 96 hours.
- 21. The method of claim 20, wherein said elevated temperature and said elevated pressure are maintained from 5 minutes to 24 hours.
- 22. The method of claim 21, wherein said elevated temperature and said elevated pressure are. maintained from about 5 minutes to about 1 hour.
- 23. The method of claim 1, wherein said colored Type II natural diamond has a brownish color.
- 24. A diamond having a changed color prepared by the method of claim 1.
- 25. A diamond of claim 24, wherein the diamond is colorless.
- 26. A diamond of claim 24, wherein the diamond is a fancy-colored diamond.
- 27. The method of claim 1, wherein the recovered diamond is pink, red, blue, or a color combination thereof.
- 28. The method of claim 12, wherein said fancy-colored diamond has a color selected from the group consisting of pink, red, yellow, green, blue, purple, orange, and a color combination thereof.
- 29. The method of claim 1, wherein the colored Type II natural diamond has a weight ranging from about 0.1 to 100 carats.
- 30. The method of claim 1, wherein the colored Type II natural diamond is cut and polished when placed in said pressure-transmitting medium.
- 31. The method of claim 1, wherein the recovered diamond is subsequently cut and polished.
- 32. The method of claim 31, wherein the cut is selected from the group consisting of Brilliant, Old Miners, Old European, Baguette, Triangle, Emerald, Elliptical, and Free Form.
- 33. The method of claim 32, wherein said Old European cut comprises Perruzi and Mazarin; said Elliptical cut comprises Pear, Heart, Oval and Marquise; and said Free Form cut comprises Scimitar, Briollete, State and Nation.
- 34. The method of claim 1, wherein the recovered diamond has a Gemological Institute of America Clarity Grade of about FL, IF, VVS1, VVS2, VS1, VS2, SI1 or SI2.
- 35. The method of claim 12, wherein the recovered diamond has a Gemological Institute of America color grade selected from the group consisting of D, E, F, G, H, I, J, K, L, M, N, O, P, Q and R.
- 36. The method of claim 28, wherein the recovered diamond has a Gemological Institute of America color grade selected from the group consisting of D, E, F, G, H, I, J, K, L, M, N, O, P, Q and R.
RELATED APPLICATIONS
[0001] This application claims benefit under 35 U.S.C. § 120 to U.S. application Ser. No. 09/162,206, filed Sep. 28, 1998, and U.S. application Ser. No. 08/966,642, filed Nov. 10, 1997, which is a continuation-in-part of and U.S. application Ser. No. 08/953,701, filed Oct. 17, 1997, all of which are herein incorporated by reference in their entirety.
Continuation in Parts (3)
|
Number |
Date |
Country |
Parent |
09162206 |
Sep 1998 |
US |
Child |
10338136 |
Jan 2003 |
US |
Parent |
08966642 |
Nov 1997 |
US |
Child |
10338136 |
Jan 2003 |
US |
Parent |
08953701 |
Oct 1997 |
US |
Child |
08966642 |
Nov 1997 |
US |