Working in partnership with new diamonds of Siberia and their Research and Development Manager, Dr. Victor Vins, Lucent has developed a unique multiple-step procedure to treat natural, type Ia diamonds. The result is colors that range from brown to purple and pink-to-red through HPHT annealing, irradiation, and low pressure annealing at relatively low temperatures. Those diamonds that result in a pink to red color are sold under the trade name Imperial Red Diamonds.
Lucent President Alex Grizenko began the Conference with a briefing on the history and evolution of the treatment process, also covering future production capabilities and marketing plans. Grizenko pointed out that all Lucent-treated diamonds (other colors besides red are produced) will be fully disclosed, including a laser inscription. Grizenko was joined by Vins, for whom he interpreted, in answering question about the technology behind the treatment.
Both Grizenko and Vins described some of the complications involved with their treatment procedure as a result of the HPHT conditions – temperature above 2,510°C and a pressure of 70 kilobars – so Lucent uses primarily higher clarity stones. Those that survive end up with clarity grades in the VS2- SI1 clarity range, said Grizenko. “Color is usually created at the expense of clarity.” He added that the treated diamonds are cut shallow to maximize their color.
Several of the Lucent diamonds were available for viewing by Conference participants, along with natural pink diamonds supplied by Argyle Diamonds, Ltd. Joseph Casella, Argyle’s senior sales executive for Europe and the U.S.; led the team of Argyle representatives at the Conference.
“The process used by Lucent is a stable and permanent treatment,” said Smith, “and no residual radioactivity was detected.” He added, ‘Several standard gemmological properties and characteristics, as well as advanced analytical techniques, will readily identify these diamonds as treated-color, natural-origin diamonds.”
Smith explained the distinguished characteristics of the Lucent Imperial diamonds, based on GIA’s research, and he illustrated with side-by-side photomicrographs and spectra comparing treated-color and natural-color diamonds. These characteristics include etched surfaces, graphitized coating on mineral inclusions, color zoning, strain patterns, fluorescence, visible luminescence and spectroscopy. A detailed discussion of how these characteristics are used to identify these HPHT treated-color diamonds follows :
The HPHT steps of the treatment process facilitate the de-aggregation of nitrogen defects, resulting in single substitutional nitrogen (Ib component), as well as other defects, while the subsequent high-energy electron irradiation and relatively lower temperature annealing provide a further reconfiguration of defects to produce the necessary color-causing centres, in addition to others that are characteristic of these treatment methods.
Low temperature Raman PL and UV/Vis/NIR spectroscopy further revealed a series of strong absorptions of N-V centres at 637 and 575 nm, 594, H3/H4 at 503, and 496 nm, N3 at 415 nm, as well as others, the combination of which Smith indicated has never been found in natural-color diamonds. Smith said the GIA Gem Laboratory issues a GIA Gemological Identification Report, not a GIA Diamond Grading Report or Diamond Dossier, for Lucent treated-color diamonds.
Following Smith’s presentation, Conference participants examined natural-color and treated-color diamonds using microscopes, a spectroscope and a UV lamp provided by GIA Instruments. Smith, Grizenko, Vins and representatives of Argyle assisted and answered question. All of the diamonds used in the hands-on part of the Conference were provided by Lucent Diamonds and Argyle Diamonds.
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