1,739,841 research outputs found
The stuff of legend: diamonds and development in southern Africa
Full text linkThis essay establishes four propositions. First, the diamond industry has been a positive force for development in southern Africa. Second, jewelry, among the most profitable segments of the industry, is a non-essential luxury, and accordingly, consumer concerns over conflict diamonds pose a long-term threat to the industry. Third, key in conflict diamonds is violent political conflict, not diamonds per se. Fourth, the continuing challenges shared by the industry, the NGOs, and public sector are to strengthen the Kimberley Process Certification System (KPCS) to eradicate trade in conflict diamonds and to enhance the related Diamond Development Initiative to regularize artisanal production and bring the diggers into the system.diamonds, resource curse, Kimberley process, South Africa, Botswana, Namibia
Hard Assets: The Returns on Rare Diamonds and Gems
Full text linkThis paper examines the investment performance of diamonds and other gems (sapphires, rubies, and emeralds) over the period 1999-2010, using a novel data set of auction transactions. Between 1999 and 2010, the annualized real USD returns for white and colored diamonds equaled 6.4% and 2.9%, respectively. Since 2003, the returns were 10.0%, 5.5%, and 6.8% for white diamonds, colored diamonds, and other gems, respectively. Both white and colored diamonds outperformed the stock market over our time frame. Nevertheless, gem returns are positively correlated with stock market returns, suggesting the existence of stock market wealth effects.Auctions;Diamonds;Gems;Hedonic regressions;Alternative investments
A study of unusual diamonds from the George Creek K1 Kimberlite dyke, Colorado
No full textCathodoluminescence photomicrographs of diamonds from the George Creek Kl (section 28) kimberlite dyke in Colorado reveal complex intergrowth relationships between CO?-free and CO?-bearing diamond growth generations. The distribution of the CO?-bearing diamond in some specimens suggests that this generation is younger than the CO?-free diamond growth generation, although the age relationships are mostly ambiguous. CO?-bearing diamond appears to have crystallized from fluids which invaded fractures and etched embayments in the CO?-free diamond growth generation, which shows evidence of plastic deformation. The CO?-free diamond growth generation commonly exhibits features caused by extreme plastic deformation during mantle residence time. Abundant yellow-green plastic slip planes transect zones of customary blue cathodoluminescence in many diamonds, and raised lamination lines have been recognized on resorption surfaces. The complexity and intensity of surface etch features in most George Creek diamonds, including the CO?-bearing growth generation, suggests that the diamonds were subjected to multiple episodes of etching and resorption. Extensive development of hexagonal and trigonal etch pits resulted from the action of oxidizing CO?-H?O fluids, and some late-stage etching is believed to have occurred in the hypabyssal dyke system prior to kimberlite eruption
NEW TECHNIQUES FOR TRACE ELEMENT AND RADIOGENIC ISOTOPE MEASUREMENT OF DIAMONDS: THEIR APPLICATION TO DIAMOND PETROGENESIS AND SOURCE TRACING
Full text linkTo investigate impurities in diamond we have developed an offline laser ablation method to acquire radiogenic isotope compositions and quantitative trace element determinations on diamond. This information has the potential to be used as both a petrogenetic tracer and as a tool in determining the geographic region of origin of particular diamonds. Trace element abundances are determined by sector-field ICPMS and isotope ratios are analysed via TIMS (Sr) and multi-collector ICPMS (Nd-Pb). To report quantitative trace element data the analyte mass we require from a given ablated sample volume is <1 pg for most elements, except for Sr, Zr, Ba which require between 2 – 30 pg, and for Pb ~40 pg.
Diamonds show broad LILE and LREE enrichment and HFSE and HREE depletion. Trace element systematics in fibrous diamonds are mimicked in monocrystalline diamonds. Monocrystalline diamonds display 87Sr/86Sr(i) = 0.7014±0.0010 to 0.70864±0.00004 and fibrous diamonds display 87Sr/86Sr(i) = 0.70386±0.00005 to 0.712406±0.00007. The isotope data show no defined isochron systematics that could be used for dating purposes. The parental fluids of fibrous and monocrystalline diamonds are thought to be derived through a similar multi-component mechanism. Diamond formation will result from the interaction between 1) a primitive, volatile and carbonate-rich, silicate liquid with an unradiogenic Sr signature ascending from the asthenosphere and 2) other components with more radiogenic Sr, akin to more ancient, enriched and vein-dominated lower lithosphere e.g. glimmerite/ PIC assemblages and the sources of Group II kimberlites.
We have demonstrated, using >100 diamonds from the Ekati, Diavik, Snap Lake and Congo kimberlites, that statistical processing of data using analysis of variance and logistic regression can allow source discrimination of ‘unknown’ samples. For logistic regression the most successful models focus on differences in Nb, Eu, Rb and Th data. This method shows good potential for use in a diamond fingerprinting programme
The evolution of hydrogen defects in diamonds
No full textreservedEarth is a unique planet as liquid water covers 70% of its surface, but the origin of Earth’s water is still a mystery. Many studies consider an extra-terrestrial origin of water (i.e. water was delivered by hydrated materials such as carbonaceous-chondrites and/or comets that formed in the outer Solar System) as the most accreditable theory. In order to establish what are the best candidates to be the source of water on Earth, the H isotopic composition (D/H ratio) of different extra-terrestrial objects must be analysed and compared to that of Earth’s Ocean. However, there is the possibility that the D/H ratio of Earth’s Ocean may not represent the primordial D/H. The best minerals that one can use for this purpose are diamonds. Diamonds are chemically inert and are resistant to biological, chemical and/or physical alteration. They can be very old, up to 3.5 Ga, and they are mined in almost every continent, so they are capable of sampling the entire mantle worldwide. However, an important factor to consider in order to correctly interpret the D/H of natural diamonds is whether the diffusion rate of H in diamond is fast. In fact, if the diffusion rate of H is fast, then the D/H ratio measured in diamond may not reflect the primordial (H2O-bearing) fluids from which it crystallized. Some recent studies show that the H diffusion rate is high in CVD (Chemical Vapor Deposition) diamonds (see Cherniak et al., 2018), but these studies are based on artificial diamonds, which have different structural/growth properties compared to natural diamonds. In fact, the behaviour of H may be significantly different in natural diamonds compared to CVD diamonds, and moreover, the interaction of H with N-related defects is something that has been largely ignored until now. The aim of this thesis is to better understand the H-related defects present in some natural diamonds. These defects are detected using Fourier Transform Infrared (FTIR) spectroscopy. Raw FTIR spectra are processed using different software to obtain information about the defects related to the nitrogen (N) and H. A comparative analysis was done to understand how the H-related defects change at different N-aggregation states, from the moment of initial diamond formation to the time at which B-centers form after long mantle residence times. In doing so, a history of the diamonds is constructed where particular N-aggregation states are shown to mark the appearance (or disappearance) of IR peaks that correspond to different H-related defects. The results show that the H diffusion rate may be almost zero once H is trapped by N-related defects. In fact, many different H-related defects are present in Type Ib to Type IaB diamonds. In general, the number of unique H-defects decreases as N-aggregation progresses, this suggests that many different H-defects combine to form much fewer, relatively more stable defects, over time. These H-defects in Type IaB diamond, that represent the end state of N-aggregation, are observed as two peaks at 3107 and 3236 cm-1 corresponding to the VN3H and VN4H defects, respectively. In Type IaB diamond, these peaks are much more intense than other H-peaks observed in Type Ib + IaA diamond and thus it is likely that most H-related defects eventually combine (aggregate) to form VN3H or VN4H given enough time at sufficiently high mantle residence temperatures. However my interpretations must be confirmed by high-temperature, high-pressure annealing studies of diamond samples studied here to further constrain how N/H-defects evolve with increasing temperature, pressure and time. Nevertheless, my results represent an important piece of information that must be considered when interpreting the D/H ratio of diamonds measured with the Isotope Ratio Mass Spectrometry or other techniques. Such data, coupled with the age of the diamonds, will provide insights into the primordial D/H ratio of Earth and how it changed through time.Earth is a unique planet as liquid water covers 70% of its surface, but the origin of Earth’s water is still a mystery. Many studies consider an extra-terrestrial origin of water (i.e. water was delivered by hydrated materials such as carbonaceous-chondrites and/or comets that formed in the outer Solar System) as the most accreditable theory. In order to establish what are the best candidates to be the source of water on Earth, the H isotopic composition (D/H ratio) of different extra-terrestrial objects must be analysed and compared to that of Earth’s Ocean. However, there is the possibility that the D/H ratio of Earth’s Ocean may not represent the primordial D/H. The best minerals that one can use for this purpose are diamonds. Diamonds are chemically inert and are resistant to biological, chemical and/or physical alteration. They can be very old, up to 3.5 Ga, and they are mined in almost every continent, so they are capable of sampling the entire mantle worldwide. However, an important factor to consider in order to correctly interpret the D/H of natural diamonds is whether the diffusion rate of H in diamond is fast. In fact, if the diffusion rate of H is fast, then the D/H ratio measured in diamond may not reflect the primordial (H2O-bearing) fluids from which it crystallized. Some recent studies show that the H diffusion rate is high in CVD (Chemical Vapor Deposition) diamonds (see Cherniak et al., 2018), but these studies are based on artificial diamonds, which have different structural/growth properties compared to natural diamonds. In fact, the behaviour of H may be significantly different in natural diamonds compared to CVD diamonds, and moreover, the interaction of H with N-related defects is something that has been largely ignored until now. The aim of this thesis is to better understand the H-related defects present in some natural diamonds. These defects are detected using Fourier Transform Infrared (FTIR) spectroscopy. Raw FTIR spectra are processed using different software to obtain information about the defects related to the nitrogen (N) and H. A comparative analysis was done to understand how the H-related defects change at different N-aggregation states, from the moment of initial diamond formation to the time at which B-centers form after long mantle residence times. In doing so, a history of the diamonds is constructed where particular N-aggregation states are shown to mark the appearance (or disappearance) of IR peaks that correspond to different H-related defects. The results show that the H diffusion rate may be almost zero once H is trapped by N-related defects. In fact, many different H-related defects are present in Type Ib to Type IaB diamonds. In general, the number of unique H-defects decreases as N-aggregation progresses, this suggests that many different H-defects combine to form much fewer, relatively more stable defects, over time. These H-defects in Type IaB diamond, that represent the end state of N-aggregation, are observed as two peaks at 3107 and 3236 cm-1 corresponding to the VN3H and VN4H defects, respectively. In Type IaB diamond, these peaks are much more intense than other H-peaks observed in Type Ib + IaA diamond and thus it is likely that most H-related defects eventually combine (aggregate) to form VN3H or VN4H given enough time at sufficiently high mantle residence temperatures. However my interpretations must be confirmed by high-temperature, high-pressure annealing studies of diamond samples studied here to further constrain how N/H-defects evolve with increasing temperature, pressure and time. Nevertheless, my results represent an important piece of information that must be considered when interpreting the D/H ratio of diamonds measured with the Isotope Ratio Mass Spectrometry or other techniques. Such data, coupled with the age of the diamonds, will provide insights into the primordial D/H ratio of Earth and how it changed through time
Diamonds as an Alternative Investment Class - An Application of the Modern Portfolio Theory with Diamonds
No full textDespite the increasing popularity in passion investments and alternative investments, many of the questions around their applicability in a portfolio context are still unknown to science. The underlying motivation of this paper is the investigation of diamonds’ suitability in an investor’s portfolio. By comparing different carat sizes as well as clarity and color grades, the aim is to find the physical diamonds, which have the best risk-return relationship. Furthermore, a correlation analysis is carried out, which should confirm a diamond’s image of a safe haven investment.
Diamonds neither yield any interest, nor pay out any dividends. Furthermore, there is no guarantee that the price will increase over time. So, can a diamond even be purchased solely for financial motives or will the emotional motives also dominate in the future
Conflict Diamonds
Full text link’Conflict diamonds’ refers to the fatal role that diamonds are believed to have played in several African conflicts. The article analyzes the impact of diamond abundance on economic growth in light of the broader, previously discovered empirical finding of a ’curse of natural resources’. By extending the theory of appropriative conflict, a predator-prey game is outlined in which a rebel chooses between peaceful production and predation on natural resources controlled by the ruler. It is shown that whereas an increase in natural resources will increase the ruler’s public utility investments, it might also lead to a crowding-out of labor from the formal sector to the appropriative struggle, which depresses growth. As predicted by the model, a cross-country regression analysis suggests that diamond abundance has a negative relationship with economic growth in countries with weak institutions.diamonds, appropriative conflict, curse of natural resources, growth, predation.
Chiadzwa Diamonds: Zimbabwe’s potential economic recovery option
Full text linkThe research was motivated by the need for Zimbabwe’s financial assistance to kick-start the recovery of its economy from the meltdown it has been for more than a decade. Since the formation of the government of national unity (GNU) on February 13, 2009, government of Zimbabwe’s (GoZ) begging bowl for US1 billion and US8.3 billion can be wholly met with proceeds from this mine field only if the new unity government has a political will. Partial projections presented in this paper shows that, once diamond revenue sales are harnessed by the government for the benefit of the whole economy as opposed to the current situation where the few revenues are only benefiting few politicians and their relatives, the country’s GDP can jump from the 2008 level of US16.7 billion starting 2009. The paper also suggested management frameworks that the GoZ can consider implementing in the management of Chiadzwa diamond.Chiadzwa diamonds, economic recovery, US$8.3 billion
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[News Clip: Diamonds]
No full textVideo footage from the WBAP-TV television station in Fort Worth, Texas, to accompany a news story about $100,000 worth of diamonds being delivered to Dallas for a Zales display at Southern Methodist University
Micro-morphology and Resorption features of Diamonds from Snap Lake and Ekati Kimberlites (Canada) as an Indicator of Kimberlite Emplacement Conditions
No full textVolatiles play a significant role in the emplacement mode and the resulting geology of kimberlites, however, the volatile composition and concentrations are poorly constrained. Previous experimental studies have suggested that diamond resorption features are sensitive to the presence and composition of C-O-H fluids. Atomic force microscopy (AFM) can be used to quantify individual features on diamonds to place robust constraints on their resorption conditions and the composition of kimberlitic fluid.
This study examines resorption features on diamonds from kimberlite localities with presumably different fluid and emplacement histories - Snap Lake kimberlite dyke and four kimberlite pipes (Fox, Panda, Koala, Misery) from Ekati Mine. The morphologies of 251 diamonds from Snap Lake were examined and 91 crystals with octahedral or tetrahexahedral forms were selected, which were further divided via optical microscopy and Scanning Electron Microscopy (SEM) into 12 morphological groups based on the resorption features on {111} faces. Related sub-groups were identified based on the edge types. The internal properties (N content and aggregation state) of 82 diamonds selected from different morphological groups were also examined by Fourier Transform Infrared Spectroscopy (FTIR). The lack of correlation between the internal properties of diamonds and resorption morphologies suggests a limited effect of internal factors on resorption morphologies.
Selected diamonds from Snap Lake and Ekati kimberlites were studied with Atomic Force Microscopy (AFM) to provide quantitative data on the geometry of diamond micro-features. The results were compared to the AFM data for diamonds etched in experiments at 0.1 MPa in H2-CO2 gas mixture and at 1-3 GPa in CHO fluid with various CO2/(H2O+CO2) ratios. Snap Lake diamonds show widespread development of positive trigons in addition to the common negative trigons, indicating late-stage etching at near-surface conditions superimposed on earlier stage (deeper) etching. Ekati diamonds show only negative trigons implying deeper resorption (at pressures ≥ 1 GPa). The AFM data show significant variation in CO2/H2O ratio between the volumetrically dominant coherent facies (HKM) and the subordinate phlogopite-rich coherent facies (HKP) in Snap Lake kimberlite, and among the four studied Ekati kimberlites. The differences in the emplacement of Snap Lake dyke and Ekati kimberlite pipes can be explained by variation in fluid composition. The study shows that the new AFM-based method of examining trigonal pits on diamonds can be applied to reconstruct conditions during kimberlite emplacement and the nature of kimberlitic fluids
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