While the first part of this study took a detailed look at the properties, defects and classification of brown diamonds with deformation-related (DR) brown color and compared them to pink to purple to red diamonds, this second part covers diamonds with non-deformation-related (referred to as NDR in this study) brown color, including diamonds with treatment-induced brown color and synthetic brown diamonds. It was found that the natural NDR brown diamonds include CO₂ and Pseudo CO₂ diamonds as well as certain hydrogen-rich diamonds. Based on these, the new classification of NDR brown diamonds has been elaborated, resulting in 5 different classes. The detailed defect study performed has shown and confirmed the complexity of the CO₂ and Pseudo CO₂ diamonds; the probable link between structurally bound oxygen and some of the spectroscopic features such as the 480 nm absorption band is apparent in these diamonds. One of the most interesting findings was made through the low temperature NIR spectroscopy of some usually hydrogen-rich diamonds, which has defined a defect of great interest, the 1330 nm center; we suggest that this defect, together with the many lines in the 970 to 1000 nm range—referred to as the 990 nm series in this study—are responsible for the complex UV-Vis-NIR spectra seen of these diamonds. The results indicate that both features are nickel-nitrogen-related defects, the 1330 nm defect without involvement of hydrogen and the 990 nm series likely with hydrogen involved. Another surprising result was that during various treatment experiments performed we created dark orangish brown color in originally pale yellow “cape” diamonds by HPHT treatment at 2500 °C. It is suggested that the creation of this brown hue is related to the destruction or transformation of the N3 center at such extreme conditions.

中文翻译：

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与变形无关的棕色钻石的缺陷研究和分类

本研究的第一部分详细研究了具有变形相关（DR）棕色的棕色钻石的特性，缺陷和分类，并将它们与粉红色到紫色到红色的钻石进行了比较，而第二部分则涵盖了不变形的钻石相关的（在本研究中称为NDR）棕色，包括具有治疗引起的棕色的钻石和人造棕色钻石。发现天然的NDR棕色钻石包括CO ₂和伪CO ₂钻石以及某些富氢钻石。在此基础上，详细阐述了NDR棕色钻石的新分类，从而产生了5种不同的类别。进行的详细缺陷研究表明并确认了CO ₂和Pseudo CO ₂的复杂性钻石; 在这些钻石中，结构结合的氧与某些光谱特征（例如480 nm吸收带）之间可能存在联系。最有趣的发现之一是通过一些通常富含氢的钻石的低温NIR光谱学得出的，该钻石定义了一个令人关注的缺陷，即1330 nm中心。我们建议将此缺陷与970至1000 nm范围内的许多谱线（在本研究中称为990 nm系列）一起归因于这些钻石的复杂UV-Vis-NIR光谱。结果表明，这两个特征都是与镍-氮有关的缺陷，没有氢参与的1330 nm缺陷和可能涉及氢的990 nm系列。另一个令人惊讶的结果是，在进行的各种处理实验中，我们通过2500°C的HPHT处理，在原本浅黄色的“斗篷”钻石中产生了深橘红色。建议在这种极端条件下，这种棕色色调的产生与N3中心的破坏或转变有关。