gems, history of gemology, history of the gem trade, Russia, Ottomans, Mughal, diamond, ruby

This dissertation analyzes the Early Modern global luxury commodity trade of diamonds and gems conducted between the Indian Subcontinent and the Mediterranean during 1670s and 1730s. It examines the involvement of the Armenian mercantile network of merchants from New Julfa, Isfahan in this global trade by focusing on the previously unpublished and unstudied body of archival documents from state and private archives in Italy, the UK, Armenia, Iran and beyond. By focusing on a single family firm of professional gem merchants, the Minasians, their network of agents and business activities, this dissertation argues against the previously presumed idea by economic historians that early modern Asian merchants and family firms were merely peddlers in the face of the European chartered joint-stock companies. Operating from Isfahan and Livorno all the way to the Russian, Ottoman and Mughal Empires, the previously little-studied Minasian archival documents demonstrate that these gem merchants’ business ventures covered vast distances and included all three “gunpowder empires” of the early modern period. This dissertation also sheds light on the specifics of decision making, as well as the role of social capital in the long-distance business operations of this family firm. It argues that the systematic circulation of information and market knowledge played a key role in the business and decision-making culture of this family firm. Moreover, their detailed knowledge of early modern gem markets and the efficient information circulation through correspondence provided the most accurate, combined use of the caravan and maritime trade routes, whichever was cheaper and safer at any one moment. By offering a new narrative on the agency of the Minasian family firm in the early modern Eurasian long-distance trade, this dissertation makes an argument that the above-mentioned practices could be representative of a bigger body of Asian family firms operating in late seventeenth and eighteenth century Eurasia.

gems, origin determination, ruby, sapphire

“As we go about our daily lives, caste is the wordless usher in a darkened theater, flashlight cast down in the aisles, guiding us to our assigned seats for a performance. The hierarchy of caste is not about feelings or morality. It is about power—which groups have it and which do not.” Beyond race, class, or other factors, there is a powerful caste system that influences people’s lives and behavior and the nation’s fate. Linking the caste systems of America, India, and Nazi Germany, Isabel Wilkerson explores eight pillars that underlie caste systems across civilizations, including divine will, bloodlines, stigma, and more. Using riveting stories about people—including Martin Luther King, Jr., baseball’s Satchel Paige, a single father and his toddler son, Wilkerson herself, and many others—she shows the ways that the insidious undertow of caste is experienced every day. Finally, she points forward to ways America can move beyond the artificial and destructive separations of human divisions, toward hope in our common humanity.

gems, corundum, Australia.12

Short descriptions of all of the sapphire deposits in Australia.

gems, corundum, chemistry.3, spinel, Mozambique.12,

Great collection of technical articles on ruby, sapphire and spinel.

gems, corundum, Sri Lanka.12, Rakwana

gems, corundum, Australia.12, USA.12, Montana.12

gems, diamond, corundum, inclusions

gems, corundum, geology.11

Corundum is not uncommon on Earth, but the gem varieties of ruby and sapphire are relatively rare. Gem corundum deposits are classified as primary and secondary deposits. Primary deposits contain corundum either in the rocks where it crystallized or as xenocrysts and xenoliths carried by magmas to the Earth’s surface. Classification systems for corundum deposits are based on different mineralogical and geological features. An up-to-date classification scheme for ruby deposits is described in the present paper. Ruby forms in mafic or felsic geological environments, or in metamorphosed carbonate platforms, but it is always associated with rocks depleted in silica and enriched in alumina. Two major geological environments are favorable for the presence of ruby: (1) amphibolite to medium pressure granulite facies metamorphic belts and (2) alkaline basaltic volcanism in continental rifting environments. Primary ruby deposits formed from the Archean (2.71 Ga) in Greenland to the Pliocene (5 Ma) in Nepal. Secondary ruby deposits have formed at various times from the erosion of metamorphic belts (since the Precambrian) and alkali basalts (from the Cenozoic to the Quaternary). Primary ruby deposits are subdivided into two types based on their geological environment of formation: (Type I) magmatic-related and (Type II) metamorphic-related. Type I is characterized by two sub-types, specifically Type IA where xenocrysts or xenoliths of gem ruby of metamorphic (sometimes magmatic) origin are hosted by alkali basalts (Madagascar and others), and Type IB corresponding to xenocrysts of ruby in kimberlite (Democratic Republic of Congo). Type II also has two sub-types: metamorphic deposits sensu stricto (Type IIA) that formed in amphibolite to granulite facies environments, and metamorphic-metasomatic deposits (Type IIB) formed via high fluid–rock interaction and metasomatism. Secondary ruby deposits, i.e., placers, are termed sedimentary-related (Type III). These placers are hosted in sedimentary rocks (soil, rudite, arenite, and silt) that formed via erosion, gravity effect, mechanical transport, and sedimentation along slopes or basins related to neotectonic motions and deformation.

gems, corundum, inclusions.5, Burma.12, zircon, zirconolite, Mogok, spinel

The Mogok area in Myanmar (Burma) is known since historic times as a source for some of the finest rubies and spinels in the world. In this study, we focus on in-situ U–Pb geochronological analyses of zircon and zirconolite, either present as inclusions in gem-quality ruby and spinel or as accessory minerals in ruby- and spinel-bearing marble and adjacent granulite facies gneisses. The age determination was carried out using both laser ablation inductively coupled plasma time-of-flight mass spectrometry (LA-ICP-TOF-MS) and sector-field mass spectrometry (LA-ICP-SF-MS). In addition, we present multi-element data (REE) of zircon and zirconolite collected with LA-ICP-TOF-MS to further characterize these inclusions. Most of the studied zircon grains display growth zoning (core/rim) regardless if as inclusion in gemstones, or as accessory mineral in host rock samples. U–Pb dating was conducted on both core and rim of zircon grains and revealed most ages ranging from ~200 Ma in the core to ~17 Ma in the rim. The youngest U–Pb ages determined from the rim of zircon inclusions in gem-quality ruby and spinel are 22.26 ± 0.36 Ma and 22.88 ± 0.72 Ma, respectively. This agreement in U–Pb ages is interpreted to indicate a simultaneous formation of ruby and spinel in the Mogok area. In ruby- and spinel-bearing marble from Bawlongyi, the youngest zircon age was determined as 17.11 ± 0.22 Ma. Furthermore, U–Pb age measured on the rim of zircon grains in a biotite-garnet gneiss reveals a Late Oligocene age (26.13 ± 1.24 Ma), however older ages up to Precambrian age were also recorded in the cores of zircon as accessory minerals from this gneiss. These old ages point to a detrital origin of the analysed zircon cores. Although non-matrix matched standard was applied, zirconolite U–Pb age results are narrower in distribution from ~35 Ma to ~17 Ma, falling within the range of zircon ages. Based on results which are well in accordance with previous geochronological data from the Mogok Metamorphic Belt (MMB), we deduce that gem-quality ruby and spinel from Mogok probably formed during a granulite-facies regional metamorphic event in Oligocene to Early Miocene, related to post collision tectonics of the Eurasian and Indian plates. Our data not only provide key information to understand the formation of gem-quality ruby and spinel in the so-called Mogok Stone Tract, but also provide assisting evidence when determining the country of origin of gemstones in gemmological laboratories.

gems, trapiche gems, beryl, emerald, corundum, ruby, sapphire