General Electric Company

Diamond Innovations. Inc.

Bellataire International, LLC

Alan Cameron Smith

Thomas R Anthony

Suresh Shankarappa Vagarali

John Kieran Casey

Steven William Webb

Robert C DeVries

John William Lucek

William Edwin Jackson

Biju Varghese

Stephen Lee Dole

Yavuz Kadioglu

William Frank Banholzer

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.

High pressure and high temperature production of diamonds

A jadeite material has a thickness in excess of about 1.0 mm and CIELAB indices of L*&#x3e;42, a*&#x3c;&#x2212;6, and b*&#x3e;+6. The grain size of the jadeite material is less than about 30 microns and is an equiaxed grain structure. The jadeite material has an optical transmission peak between 500 and 565 nm with an I/Ioptical transmission ratio of over 40%. The first step in making the jadeite material is to wrap a glass block, convertible by HP/HT into jadeite and having a nominal composition of NaAlSiO, with a graphite or refractive metal sheet. The wrapped glass block is placed in an HP/HT apparatus, rapidly heated, and subjected therein to a pressure in excess of about 3 GPa and a temperature in excess of about 1000&#xb0; C. for a time adequate to convert the glass block into jadeite. The jadeite material then is cooled and the pressure subsequently released.

Jadeite and its production

A method for detecting whether a natural diamond has been processed at high pressure and high temperature (HPHT) conditions comprises steps of disposing the diamond in a cyrostat that is provided at temperatures equal to or less than liquid nitrogen; illuminating the diamond with a laser beam; recording an optical spectrum of the diamond with a photoluminescence spectrometer; and examining the optical spectrum of the diamond to detect an absence of selected photoluminescent spectral lines. The invention also sets forth a method for predicting whether a natural diamond has been treated under HPHT conditions

Method of detection of natural diamonds that have been processed at high pressure and high temperatures

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Dublin, Ireland

Alan Cameron Smith