High pressure and high temperature production of diamonds

Details High pressure and high temperature production of diamonds High pressure and high temperature production of diamonds

2007-07-10

2007-07-10

Hendrickson, Stuart (Department: 1754)

Chemistry of inorganic compounds

Carbon or compound thereof

Elemental carbon

C117S929000, C423S264000

Reexamination Certificate

active

10344249

ABSTRACT:
The present invention is directed to a method for treating discolored natural diamond, especially Type IIa diamond and Type IaA/B diamond with nitrogen as predominantly B centers, for improving its color. The method includes preblocking and preshaping a discolored natural diamond to prevent its breakage in a high pressure/high temperature (HP/HT) press, placing said discolored natural diamond in a pressure transmitting medium which is consolidated into a pill. Next, the pill is placed into a HP/HT press at elevated pressure and elevated temperature within the graphite-stable or diamond-stable range of the carbon phase diagram for a time sufficient to improve the color of said diamond. Finally, the diamond is recovered from said press. Colorless and fancy colored diamonds can be made by this method.

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