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Spectroscopic features of natural and HPHT-treated yellow diamonds
Diamond and Related Materials ( IF 4.1 ) Pub Date : 2020-01-01 , DOI: 10.1016/j.diamond.2019.107642
Mei Yan Lai , Christopher M. Breeding , Thomas Stachel , Richard A. Stern

Abstract High pressure high temperature (HPHT) treatment has long been applied in the gem trade for changing the body colour of diamonds. The identification of HPHT-treated diamonds is a field of on-going research in gemological laboratories, as different parameters of treatment will result in either the creation or the destruction of a variety of lattice defects in diamonds. Some features that exist in treated diamonds can also be found in natural diamonds, and consequently must not be employed for the separation of treated and natural diamonds. In this research, we investigated the properties of 11 natural yellow diamonds (directly obtained from the Ekati Diamond Mine to ensure that they are untreated) before and after HPHT treatment, conducted at a temperature of 2100 °C and a pressure of 6 GPa for 10 min. We report spectroscopic data and fluorescence characteristics, collected using PL mapping, FTIR mapping and fluorescence imaging showing the distribution of lattice defects and internal growth structures. PL mapping indicates Si V defects exist in one of the nitrogen-rich natural diamonds prior to treatment. Silicon-related defects can also be created by HPHT treatment, and they seem to show a relationship with pre-existing NV− centres. SIMS analysis was conducted to confirm the presence of silicon in these diamonds. The increase in the hydrogen-related infrared absorption peak at 3107 cm−1 (VN3H) is very strong in some diamonds that do not form B-centres during treatment. NVH was observed in our HPHT-treated natural diamonds, so it is possible that this strong increase in VN3H suppresses the aggregation of A- to B-centres as the newly formed A-centres were captured by NVH lattice defects to form VN3H. HPHT-altered and HPHT-induced platelet peaks are different from their natural counterparts in peak width and shape. Strong green fluorescence over a large area of a diamond, which is linked to relatively high concentration of H3 centres, was produced after HPHT treatment. We are confident that the unusual platelet peaks and strong emission of H3 centres are reliable indicators for HPHT-treated diamonds as they are not observed in untreated natural diamonds.

中文翻译:

天然和经过高温高压处理的黄钻的光谱特征

摘要 高压高温(HPHT)处理长期以来一直应用于宝石贸易中以改变钻石的体色。鉴定经高温高压处理的钻石是宝石学实验室正在进行的研究领域,因为不同的处理参数将导致钻石中各种晶格缺陷的产生或破坏。处理过的钻石中存在的一些特征也可以在天然钻石中找到,因此不得用于区分处理过的钻石和天然钻石。在这项研究中,我们研究了 11 颗天然黄钻(直接从 Ekati 钻石矿获得以确保它们未经处理)在高温高压处理前后的特性,在 2100 °C 的温度和 6 GPa 的压力下进行 10分钟 我们报告了使用 PL 映射、FTIR 映射和荧光成像收集的光谱数据和荧光特性,这些数据显示了晶格缺陷和内部生长结构的分布。PL 映射表明在处理之前,其中一颗富含氮的天然钻石中存在 Si V 缺陷。HPHT 处理也可以产生与硅相关的缺陷,它们似乎与预先存在的 NV− 中心有关。进行 SIMS 分析以确认这些钻石中存在硅。在某些处理过程中未形成 B 中心的钻石中,3107 cm-1 (VN3H) 处与氢相关的红外吸收峰的增加非常强烈。在我们经过高温高压处理的天然钻石中观察到 NVH,因此,由于新形成的 A 中心被 NVH 晶格缺陷捕获以形成 VN3H,因此 VN3H 的这种强烈增加可能抑制了 A 中心到 B 中心的聚集。HPHT 改变和 HPHT 诱导的血小板峰在峰宽和形状上不同于它们的天然对应物。HPHT 处理后在钻石的大面积上产生强烈的绿色荧光,这与相对高浓度的 H3 中心有关。我们相信,异常的血小板峰和 H3 中心的强烈发射是 HPHT 处理钻石的可靠指标,因为它们在未经处理的天然钻石中没有观察到。HPHT 处理后在钻石的大面积上产生强烈的绿色荧光,这与相对高浓度的 H3 中心有关。我们相信,异常的血小板峰和 H3 中心的强烈发射是 HPHT 处理钻石的可靠指标,因为它们在未经处理的天然钻石中没有观察到。HPHT 处理后在钻石的大面积上产生强烈的绿色荧光,这与相对高浓度的 H3 中心有关。我们相信,异常的血小板峰和 H3 中心的强烈发射是 HPHT 处理钻石的可靠指标,因为它们在未经处理的天然钻石中没有观察到。
更新日期:2020-01-01
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