Thomas M. Moses's research while affiliated with Boston College and other places

... The X-ray transmission method (XRT) is a new separation technique that uses X-rays to detect diamonds both type I and II diamonds [11,13]. Type I diamonds contain nitrogen atoms that fluoresce when exposed to X-rays, while type II does not contain nitrogen and hence does not fluoresce when exposed to X-rays. ...

... A broad band at 320-380 nm is rarely observed in natural diamonds. Similar bands were observed in brown-yellow (Wang and Moses 2003) and pink-purple diamonds (Titkov et al. 2008). ...

... In addition, Usakos is well known for producing gem-quality blue elbaite, so it is a possible locality of origin for this unusual gem. Type IIa diamonds are generally colourless, brown or pink, and some can turn yellow after HPHT annealing by the formation of substantial nitrogen-related defects (Wang et al. 2003). In addition, Lu and Wang (2010) described an untreated greenish yellow type IIa diamond coloured by the H3 centre. ...

... Many of these samples have been described in detail in previous articles (Wang et al., 2003(Wang et al., , 2007(Wang et al., , 2012 and in G&G's Lab Notes section (e.g., Wang and Moses, 2008;Wang and Moe, 2010;Ardon et al., 2013;Wang et al., 2013;Ardon and Wang, 2014;Moe et al., 2014). Whereas earlier studies examined small batches of CVD synthetic diamonds from specific manufacturers, which were likely to have been grown using a similar recipe, the goal of the present study is to investigate trends in the distinctive features seen among CVD synthetic diamonds from multiple sources over the past 13 years. ...

... For one, in our experience whitish graining is most commonly encountered in large (e.g., over 4 ct) diamonds. Most of these large diamonds are type II (a diamond type that is relatively free of nitrogen) and often absent of solid inclusions (see, e.g., Moses and Wang, 2006). Another factor is that the complex interaction of light with a diamond's cut when viewed in the faceup position may restrict the observation of this often subtle, visually elusive feature to the pavilion, where such graining can impact the most critical clarity determination of Flawless/Internally Flawless (FL/IF) versus VVS 1 (figure 2). ...

... Nitrogen-vacancy (NV) centers, which can produce an attractive pink color in gem quality diamonds (e.g., Fig. 15), are also of great interest to the scientific community as they develop methods to harness properties of the negatively charged state of the center (NV -) for uses in quantum technology and other fields. NV centers can be created by irradiating and annealing HPHT diamonds with Downloaded from http://pubs.geoscienceworld.org/msa/rimg/article-pdf/88/1/689/5645060/rmg.2022.88.13.pdf by guest on 12 January 2023 suitable isolated nitrogen concentrations (Moses et al. 1993;Shigley et al. 2004a). The addition of nitrogen getters narrows the range of temperatures at which diamonds with good crystallinity can be grown, and leading to higher uptake of melt inclusions and associated carbides (Sumiya and Satoh 1996;Burns et al. 1999Burns et al. , 2009Sumiya et al. 2002). ...

... However, these works are gemology-oriented and provide manual guidelines for a broad spectrum of gemstones. Similarly, the work [19] provides general guidelines for a manual analysis of emerald stones, specifically. ...

... A measure of the proportion of diamonds deformed in a particular size fraction in a general diamond production can be gained by assessing the proportion of pink and brown diamonds present, as these colors are linked to plastic deformation (Collins 1982;Harris et al. 1983;Robinson et al. 1986;Fisher et al. 2009;Gaillou et al. 2010Gaillou et al. , 2012Titkov et al. 2012;Howell et al. 2015). Not all deformed diamonds are brown, however, and experiments indicate that the color can be annealed out leaving just the deformation lines (Moses et al. 1999;Collins et al. 2000) a process that can occur naturally during high temperature storage in the mantle. For further details on the relationship between plastic deformation and pink and brown coloration in diamonds see Green et al. (2022, this volume). ...

... Infrared spectroscopy often shows the occurrence of C centers (1344 cm -1 ) along with both A and B centers, another condition that is extremely rare in untreated natural diamonds (Fig. 41). In addition, platelets are usually significantly reduced by the treatment, a feature that can easily be recognized in IR spectroscopy in combination with the occurrence of C centers (Reinitz et al. 2000) (Fig. 41). ...

... Dendritic, vein-like, spiral, and lamellar or striated surface patterns can be observed on the external faces (Tolansky and Sunagawa 1959;Kanda et al. 1980;Koivula and Fryer 1984;Shigley et al. 1986Shigley et al. , 1987Shigley et al. , 1992Shigley et al. , 1997Sunagawa 1995). In particular, the dendritic surface patterns are considered to be indicative of HPHT diamonds. ...