High pressure/high temperature production of colored diamonds

The present invention is directed to a method for treating discoloured natural diamond, especially Type IIa diamond and Type IaA/B diamond with nitrogen as predominantly B centres, for improving its color. The method includes preblocking and preshaping a discoloured natural diamond to prevent its br...

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Bibliographische Detailangaben
Hauptverfasser:	KADIOGLU, YAVUZ, ANTHONY, THOMAS RICHARD, SMITH, ALAN C, WEBB, STEVEN W, VAGARALI, SURESH S, CASEY, JOHN K, BANHOLZER, WILLIAM F, JACKSON, WILLIAM E
Format:	Patent
Sprache:	eng ; fre ; ger
Schlagworte:	CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY PERFORMING OPERATIONS PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL THEIR RELEVANT APPARATUS TRANSPORTING
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Beschreibung
Zusammenfassung:	The present invention is directed to a method for treating discoloured natural diamond, especially Type IIa diamond and Type IaA/B diamond with nitrogen as predominantly B centres, for improving its color. The method includes preblocking and preshaping a discoloured natural diamond to prevent its breakage in a high pressure/high temperature (HP/HT) press, placing said discoloured 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.