High pressure/high temperature production of colorless and fancy colored diamonds

Abstract

Abstract of Disclosure 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 placing a discolored natural diamond in pressure transmitting medium powder which is consolidated into a pill. Next, the pill is placed into a high pressure/high temperature (HP/HT) press at elevated pressure and elevated temperature within the 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 diamond can be made by this method.

Dependencies are inferred from the claim text.