High pressure/high temperature production of colorless and fancy-colored diamonds
US7323156B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 15, 2003 |
| Grant date | Jan 29, 2008 |
| Priority date | — |
| Expiry date | Aug 8, 2024 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB01J2203/0695
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
The present invention is directed to a method for changing the color of colored natural diamonds. The method includes placing a discolored natural diamond in a pressure-transmitting medium 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 for a time sufficient to improve the color of the diamond. The diamond may be exposed at elevated-pressure and elevated-temperature conditions within the graphite-stable region of the carbon-phase diagram—without significant graphitization of the diamond, or above the diamond-graphite equilibrium and within the diamond-stable region of the carbon-phase diagram. Finally, the diamond is recovered from said press. Colorless Type Ia and Type II diamonds may be made by this method.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.