High-Pressure-High-Temperature Treatment of Gem Diamonds

Research Article| March 01, 2005 High-Pressure-High-Temperature Treatment of Gem Diamonds James E. Shigley James E. Shigley 1Gemological Institute of America, Research Department, 5345 Armada Drive, Carlsbad, CA 92008-4603, USA E-mail: jshigley@gia.edu Search for other works by this author on: GSW Google Scholar Author and Article Information James E. Shigley 1Gemological Institute of America, Research Department, 5345 Armada Drive, Carlsbad, CA 92008-4603, USA E-mail: jshigley@gia.edu Publisher: Mineralogical Society of America First Online: 09 Mar 2017 Online ISSN: 1811-5217 Print ISSN: 1811-5209 © 2005 by the Mineralogical Society of America Elements (2005) 1 (2): 101–104. https://doi.org/10.2113/gselements.1.2.101 Article history First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation James E. Shigley; High-Pressure-High-Temperature Treatment of Gem Diamonds. Elements 2005;; 1 (2): 101–104. doi: https://doi.org/10.2113/gselements.1.2.101 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyElements Search Advanced Search Abstract Annealing of gem-quality diamonds at very high pressures (above 5 GPa) and temperatures (above ∼1800°C) can produce significant changes in their color. Treatment under these high-pressure-high-temperature (HPHT) conditions affects certain optically active defects and their absorptions in the visible spectrum. In the jewelry industry, laboratory-treated diamonds are valued much less than those of natural color. Polished diamonds are carefully examined at gemological laboratories to determine the "origin of color" as part of an overall assessment of their quality. Currently, the recognition of HPHT-treated diamonds involves the determination of various visual properties (such as color and features seen under magnification), as well as characterization by several spectroscopic techniques. HPHT-treated diamonds were introduced into the jewelry trade in the late 1990s, and despite progress in their recognition, their identification remains a challenge. While some detection methodologies have been established, the large number of diamonds requiring testing with sophisticated analytical instrumentation poses a logistical problem for gemological laboratories. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.