Method for changing the color of discolored natural diamond and diamond prepared therefrom

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 brea...

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Bibliographische Detailangaben
Hauptverfasser:	SMITH, ALAN, C, BAGARALI, SURESH, S, BANHOLZER, WILLIAM, F, CASEY, JOHN, K, JACKSON, WILLIAM, E, WEBB, STEVEN, W, ANTHONY, THOMAS, R, YAVUZ KADIOGLU
Format:	Patent
Sprache:	eng
Schlagworte:	CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY CHEMISTRY COMPOUNDS THEREOF DRESSING OR CONDITIONING OF ABRADING SURFACES FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS GRINDING INORGANIC CHEMISTRY MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING METALLURGY NON-METALLIC ELEMENTS PERFORMING OPERATIONS PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL POLISHING PRESSES PRESSES IN GENERAL THEIR RELEVANT APPARATUS TRANSPORTING
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Beschreibung
Zusammenfassung:	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.