Natural-Color Purple Diamonds from Siberia

Titkov, S. V.; Shigley, James E.; Breeding, Christopher M.; Mineeva, R. M.; Zudin, N. G.; Сергеев, А. М.

doi:10.5741/gems.44.1.56

Cited by 32 publications

(35 citation statements)

References 16 publications

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“…The lower-aggregation category contains diamonds from several localities including South African productions (Finsch and De Beers Pool are kimberlite deposits; Koingnass and Tweepad are alluvial), Canada's Victor mine (kimberlite), and other stones from the Namibian productions. Pink diamonds from the Siberian Internatsional'naya kimberlite (Titkov et al 2008) also fall into this category, exhibiting low aggregation and significant nitrogen concentrations, and classify as group 2 pinks. Group 2 pink Notes: Uncertainties in the nitrogen concentration and aggregation data are ~10%.…”

Section: Color and Cathodoluminescencementioning

confidence: 98%

Pink color in Type I diamonds: Is deformation twinning the cause?

Howell

Fisher

Piazolo

et al. 2015

American Mineralogist

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Plastic deformation of diamond has long been associated with the generation of color, specifically brown and pink. Extensive previous optical and spectroscopic characterization of natural pink Type I (nitrogen containing) diamonds has revealed two clear groupings, with distinct geographical origins. Group 1 pinks, which have low concentrations of nitrogen and are relatively highly aggregated (IaA ≤ B), have only been found in the Argyle lamproite pipe (Australia) and Santa Elena alluvial deposits (Venezuela). Group 2 pinks, which have much higher nitrogen concentrations and exhibit low levels of aggregation, have been found in deposits from southern Africa, Canada, and Russia. Pink color is intimately associated with deformation lamellae on the {111} crystal planes, and understanding their formation and structure has been a priority with respect to defining the source of this gemologically valuable color center. In group 2 pinks, these {111} lamellae have been characterized as deformation microtwins by both transmission electron microscopy and X-ray diffraction. Subsequently the {111} lamellae in group 1 pinks have been assumed to also be deformation microtwins. In this paper we report electron backscatter diffraction (EBSD) studies of three brown and six pink naturally deformed diamonds with varying nitrogen concentrations and aggregation states. The results show that there are no deformation microtwins in the group 1 pink or brown diamonds. The study also highlights the usefulness of orientation contrast imaging as a simple and rapid method for determining the presence of microtwins. Our results suggest that the color in the group 1 pink diamonds is not directly related to the presence of deformation twins. However, we propose that twins may have been present but subsequently removed by de-twinning, a process that utilizes the same Shockley partial dislocations involved in the original twinning event. Therefore, it may be the process of twinning (and de-twinning) that creates the defect responsible for pink color, as opposed to the actual structure of microtwins themselves. In addition, a large laboratory data set of pink diamond analyses reveals the occurrence of group 1 pink diamonds in the Namibian marine (secondary) deposits. This would appear to suggest an additional source of group 1 pink diamonds in southern Africa, but the antiquity of these diamonds means that a common source on the former Pangaea supercontinent cannot be ruled out.

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Section: Color and Cathodoluminescencementioning

confidence: 98%

Pink color in Type I diamonds: Is deformation twinning the cause?

Howell

Fisher

Piazolo

et al. 2015

American Mineralogist

View full text Add to dashboard Cite

show abstract

“…Despite the fact that it is often observed in untreated brown and pink diamond crystals, very few studies have been devoted to it (Gaillou et al 2010;Titkov et al 2008;Tretiakova 2009;Hainschwang et al 2005;Yang et al 2012). According to the present study, the ZPL is accompanied by a vibrational sideband formed via the interaction with 38 and 78 meV phonons close to a quasi-local vibration of a vacancy.…”

Section: N3 H3 H4 and 4907 Nm Centersmentioning

confidence: 70%

The characteristic photoluminescence and EPR features of superdeep diamonds (São-Luis, Brazil)

et al. 2015

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“…The accurate determination of the color of diamond crystals based on comparison of sample and reference colors under standardized conditions (as is customary at the Gemological Institute of America), showed that both purple and pink colors are predominant among these crystals (Titkov et al, 2008). In addition to N2 and W7 centers, M2 centers were identified in all pink-purple diamond crystals (Fig.…”

Section: Abundance Of Deformation Defects and Their Associationsmentioning

confidence: 98%

“…E-mail: titkov@igem.ru ulation, many researchers consider N2 deformation centers as its cause (Shcherbakova et al, 1975). A pinkpurple color of diamonds is brought about by a band centered at 550 nm in the absorption spectrum, which is probably related to the M2 deformation center (Titkov et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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Structural defects in natural plastically deformed diamonds: Evidence from EPR spectroscopy

2009

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Structural defects formed as a result of plastic deformation in natural diamond crystals have been studied by EPR spectroscopy. The spectra of brown, pink-brown, black-brown, pink-purple, and gray plastically deformed diamonds of type Ia from deposits in Yakutia and the Urals were recorded. The results of EPR spectroscopy allowed us to identify various deformation centers in the structure of natural diamonds and to show that nitrogen centers were transformed under epigenetic mechanical loading. Abundant A centers, consisting of two isomorphic nitrogen atoms located in neighboring structural sites, were destroyed as a result of this process to form a series of N1, N4, W7, M2, and M3 nitrogen centers. Such centers are characterized by an anisotropic spatial distribution and a positive charge, related to the mechanism of their formation. In addition, N2 centers (probably, deformation-produced dislocations decorated by nitrogen) were formed in all plastically deformed diamonds and W10 and W35 centers (the models have not been finally ascertained) were formed in some of them. It has been established that diamonds with various types of deformation-induced color contain characteristic associations of these deformation centers. The diversity of associations of deformation centers indicates appreciable variations in conditions of disintegration of deep-seated rocks, transfer of diamonds to the Earth's surface, and formation of kimberlitic deposits. Depending on the conditions of mechanical loading, the diamond crystals were plastically deformed by either dislocation gliding or mechanical twinning. Characteristic features of plastic deformation by dislocation gliding are the substantial prevalence of the N2 centers over other deformation centers and the occurrence of the high-spin W10 and W35 centers. The attributes of less frequent plastic deformation by mechanical twinning are unusual localization of the M2 centers and, in some cases, the N1 centers in microtwinned lamellae. Numerous data on models of deformation centers in natural diamonds, including the M2 and M3 centers, which were observed in the studied collection for the first time, are discussed.

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Natural-Color Purple Diamonds from Siberia

Cited by 32 publications

References 16 publications

Pink color in Type I diamonds: Is deformation twinning the cause?

Pink color in Type I diamonds: Is deformation twinning the cause?

The characteristic photoluminescence and EPR features of superdeep diamonds (São-Luis, Brazil)

Structural defects in natural plastically deformed diamonds: Evidence from EPR spectroscopy

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