US 7,241,434 B2 · High pressure and high temperature production of diamonds

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.

Claims25

Dependent claims

A method for changing the color of brownish natural diamond, comprising:

a) blocking a brownish natural diamond to streamline a shape of the natural diamond;
b) placing said streamlined natural diamond in a pressure transmitting medium;
c) consolidating said pressure transmitting medium into a pill;
d) exposing said pill to elevated pressure and elevated temperature within the graphite-stable range or within the diamond forming range of the carbon phase diagram for a time sufficient to change the color of said diamond;
and
e) recovering said diamond.

3 more elements

Dependencies are inferred from the claim text.

Facts

Application

10/344,249Filed 8 Aug 2001

Published

US 2005/0260935 A124 Nov 2005

Granted

10 Jul 2007

Term ends

Not estimatedThe source records don’t support an estimate.

Classification11 codes

B01J 3/062
Processes using ultra-high pressure, e.g. for the formation of diamonds; Apparatus therefor, e.g. moulds or dies: characterised by the composition…
B01J 3/067
Presses for the formation of diamonds or boronitrides: presses using a plurality of pressing members working in different directions
B24B 19/16
Single-purpose machines or devices for particular grinding operations not covered by any other main group: for grinding sharp-pointed workpieces,…
B30B 11/004
Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses:…

High pressure and high temperature production of diamonds

Life of this patent

High pressure and high temperature production of diamonds

Life of this patent

Abstract

Claims25