Known as South Sea "keshi" in the trade, these non-bead cultured pearls are byproducts of the bead culturing process within the Pinctada maxima mollusk, a source of both natural and cultured pearls. The internal features of some of these non-bead cultured pearls can pose a significant challenge in pearl identification due to their similarity to structures observed in natural pearls. A group of 43 pearls showing organic-rich concentric cores, reportedly sourced from an Australian pearl farm, was selected for this study. To determine origin, their structures were analyzed and categorized using several techniques, including real-time X-ray microradiography, computed microtomography, and energy-dispersive X-ray fluorescence chemical analysis. Five of the 43 pearls were partially sanded through their cores to allow for cross-sectional analysis, including visual observations and Raman spectroscopy, to correlate the structure and composition of these cores to their X-ray imagery. The results of this study will assist in separating non-bead cultured pearls formed inside the Pinctada maxima mollusk species from natural pearls from the same species.
A rare 1688 probate inventory documents the extensive gem collection of Gregorio di Girach-Mirman (1612-1688), a prominent Armenian merchant active in Venice and Livorno, Italy. Originally written in Armenian and later translated into Italian, this archival record lists more than 100,000 gemstones, including diamonds, sapphires, emeralds, and pearls, as well as more than 1,700 kilograms of rough amber, garnet, lapis lazuli, and turquoise. Housed in the State Archives of Venice, the inventory offers a uniquely detailed window into the early modern luxury trade and highlights the global commercial reach of Armenian merchant families like the Girach-Mirmans. Drawing on this previously unstudied source, along with a broader set of archival documents from across Europe and Armenia, the present article reconstructs the world of seventeenth-century gem dealing and collecting. It argues that Armenian merchants were central figures in the global trade of luxury goods, operating alongside and sometimes in competition with better-known European contemporaries. The provenance and diversity of Gregorio's gem holdings, likely sourced from as far as modern-day Colombia, Sri Lanka, Iran, and Myanmar, attest to the geographic reach of Armenian trading networks and the sophistication of their market knowledge. By placing this inventory in its global and material context, the article contributes to ongoing discussions around early modern economic history, material culture, and global commodity flows across Eurasia and the New World. It demonstrates that gem inventories, often overlooked as solely bureaucratic and estate documents, can illuminate the complexity of merchant strategies, the transcontinental mobility of luxury goods, and the dynamics of status and prestige in the early modern period. Finally, one of the central aims of this article is to illuminate the inner workings of gem dealing in this period, including practices of sourcing and collecting, through a rare body of obscure commercial correspondence. These materials offer an exceptional view into a dimension of the trade that remains largely inaccessible and nearly absent from existing historiography.
Although green surface coloration on diamonds is mentioned in numerous studies, no morphological classification of the subject appears to exist. This study presents a classification of radiation stain morphology and texture to supplement known characteristics of naturally irradiated diamonds. "Radiation stains," as they are often termed by gemologists, are a common indicator of alpha radiation damage that can impart a green color, which may turn brown with annealing. Studying radiation stain micromorphology and textural characteristics informs us of diamond residence in sedimentary systems, which helps to better characterize green diamonds. In this study, 84 natural diamonds with radiation stains were cataloged using photomicrography. Additionally, four of these were cataloged using atomic force microscopy. These stains were classified by color, opacity, shape, and coincident surface textures. For this study, green and brown radiation stains covered up to 93% and 12% of the diamond surface, respectively. Shapes were regular (circular or oval-shaped) or irregular and formed isolated or nondiscrete color zones. In regions imaged, circular radiation stains ranged in diameter from 22-77 mu m, and oval-shaped ones ranged from 25-104 mu m at their short axis to 36-158 mu m at their long axis as viewed on their surface plane. One diamond exhibited raised surface topography coincident with radiation staining, and two had staining accompanying ruts or cracks. In 24% of the diamonds, the rare occurrence of fine negative surface topography coincident with radiation stains was documented. These features were angular to rounded, and some had acicular to tabular habits. The cause of the textural complexity coincident with radiation stains is currently a subject of debate and in some cases may involve localized diamond dissolution in the near-surface environment.
