gems, Diamond, beryl, Emerald of the Garamantes, Lamproite, Numidian Flysch, Radiohalos, Constantine, Sahara, Algeria, north Africa

It is generally believed that the first diamonds ever found in Africa were discovered in South Africa in 1867. Actually, three diamonds had already been found in 1833 near Constantine (Algeria). One of these, still preserved, shows radiohalos that suggest an old age. It could be a Sahara diamond reworked in more recent sediments, possibly the Oligo-Miocene Numidian Flysch; however, this occurrence remains uncertain. The ancient Arabs or Berbers also knew of diamonds in the Reggane region (Algerian Sahara), at Bilād al-mās (: “country of the diamond”). Since 1975, some 1500 diamonds have been collected from the alluvial deposits of this area. A manuscript written in Arabic in 1851 mentions diamonds in this region and describes their source rock, looked for in vain by modern geologists. The description is unclear, but might refer to Devonian oolitic ironstones. Modern investigations would rather suggest a kimberlitic primary source with intermediate Early Cretaceous palaeoplacers.

gems, archaeology, archaeogemology, Mediterranean, Ptolemaic-Roman, Red Sea, Egypt, Greece, Greek, beryl, emerald, Cleopatra, Sikait

The paper presents the findings of the University of Delaware and the Polish Centre of Mediterranean Archaeology's 2013–2014 field season at the archaeological site of Berenike in Egypt. Key components of the project included geophysical surveys, excavations of early Roman and Ptolemaic trash dumps, and documentation of maritime finds such as a significant portion of a Roman ship's frame. Results highlighted the potential presence of a substantial religious or administrative area, enriching our understanding of the site's historical context.

gems, pearl, coral, ruby, sapphire, spinel, beryl, emerald, Arabic mineralogy

At-Tifasi (1184-1253) wrote this book on gemstones in 1242. In it he describes a total of 25 stones valued in the upper class, including pearl and coral, among others. In the presentation, it follows a given pattern, each divided into five sections: 1. Origin, 2. Place of discovery, 3. Quality (genuine or fake), 4. Magical-medicinal effect, 5. Value and price. At the same time, he passes on well-known fables and legends, e.g. about the Alexander Treasure in the harbor of Alexandria. His sources are on the one hand the stone literature such as the Stone Book of Aristotle", on the other hand information from merchants, jewel dealers and miners. However, his own experiences with minerals are also included. This clearly structured, generally understandable document is the best-known medieval Arabic treatise on gemstones. It was a model for later authors and was translated into Persian and Turkish.In addition to a Latin (1784), an Italian (1906) and an English version (1998), a German translation is now available for the first time, which also includes a comprehensive interdisciplinary commentary and a contains image part."

jade, jadeite, jadeite, fei cui auction records for 2013, gems

This yearbook includes 44 world top auction houses such as Sotheby's, Christie's, Baolong, CITIC Macau, China Guardian (Beijing, Hong Kong), Beijing Poly, Poly Hong Kong and Beijing Hanhai. The most typical 1000 pieces of typical jadeite lottery with exact descriptions of the lot name, lot specification, auction agency, auction time, estimated price and transaction price are all about first-hand auction information. Among the 1000 jade pieces, there are 800 high-end auction items that the collectors must know representing the market trend of jadeite rables, as well as 200 pieces of low-price auction items of bargain-hunting price" level. Typical jade auction items are all included in This paper introduces the actual situation of Jadeite auction and also objectively and systematically records the development of Jadeite auction in the global auction. It is an annual jade auction yearbook which is objective, comprehensive, authoritative and highly valuable for collection and investment guidance.. For your reference and search, this yearbook will be divided into three major categories and more than 20 categories with accessories, utensils and miscellaneous items. Each auction is accompanied by detailed auction information and HD auction images, graphic combinations, set of dictionaries, catalogs, manuals, guides in one. Watched this yearbook and then shot, we will be able to accurately grasp the emerald auction market, to avoid losing sight of the market or in the auction."

gems, jade, amphibole jade, nephrite, China

In the domestic jade market, there are many different kinds of green nephrite from different regions, and Hetian nephrite is of high quality. Samples were collected from Hetian-Yutian County, Xinjiang Uyghur Autonomous Region; its gemological and mineralogical characteristics, H and O isotopic features, and the forming mechanism were studied in this investigation. Observation under microscope shows that the main microstructure of this green nephrite is woven felt-like cryptocrystalline blastic texture, the arrangements of the mineral particles result in its delicate texture and high toughness. SEM characteristics illustrate its clean topography and compactness. Study on mineral composition indicates that the major mineral component is tremolite, and then it turns into actinolite with the help of the increase of iron oxide. X-ray powder diffraction shows that the nephrite mainly consists of tremolite with minor chromite, chlorite, serpentine, clinopyroxene, and apatite. The results of infrared spectroscopy and Raman spectroscopy coincide with the results of XRD. DTA curve demonstrates that the structure of the tremolite was destroyed at 900–1100 °C. TG curve demonstrates that the tremolite has such little water that its loss of weight was only 0.89–1.33% when heated to 900–1100 °C. The geological origin of green Hetian nephrite is alteration of ultrabasic rock, and the internal black spot-like mineral is chromite which is a sign of ultrabasic rock. The analysis of hydrogen and oxygen isotopic compositions indicates that the hydrothermal fluids of Gobi aggregates are primary magmatic water, but the hydrothermal fluids of primary nephrite and gravel are unknown and still need more investigation. It is important to evaluate the quality of green Hetian nephrite. According to a comparative study of the basic characteristics of Manasi nephrite, Russian nephrite, and Canadian nephrite, Hetian nephrite is a variety of better quality and less crack. The color of Hetian nephrite is emerald green and the texture is delicate.

corundum, Burma.12, gems

The word trapiche, Spanish for “mill,” refers to the wheel that was once used to crush sugar cane. The same term is used for gems that show a characteristic six-rayed star-shaped growth zoning in cross section. This peculiar appearance, long thought to occur only in emerald, is due to bands of inclusions that radiate from the center of the crystal—the optic axis—toward the prism faces. Only in the past 20 years have other gems been discovered with a district trapiche structure, namely ruby and sapphire (K. Schmetzer et al., “Trapiche rubies,” Win-ter 1996 G&G, pp. 242–250) and tourmaline (T. Hain-schwang et al., “Trapiche tourmaline from Zambia,” Spring 2007 G&G, pp. 36–46). Generally, the trapiche ef-fect in these stones (as in emerald) is caused by dark inclu-sions. In some blue sapphires, however, it is due to strong color banding parallel to the hexagonal growth zoning. Such trapiche sapphires are known only from the Mogok region of Myanmar (K. Schmetzer, pers. comm., 2012). Recently, the Gübelin Gem Lab examined such a sap-phire, a 36.16 ct cabochon measuring 22.91 × 16.93 × 6.69 mm (figure 31). The stone showed a very pronounced blue zoning along the corners of the hexagonal growth struc-ture, while zones corresponding to the prism faces were white. In addition, many of the boundaries between the blue and the white areas displayed elongated white patches perpendicular to the growth direction of the prism faces (figure 32). Semiquantitative chemical analysis using EDXRF spec-troscopy identified both areas as corundum, with similar chemical compositions. Yet the Ti and Fe values (which cause the blue color in sapphire) as well as the Cr content were higher in the blue areas. Comparing the chemical composition of the blue portions with average concentra-tions of these elements in Burmese blue sapphires also in-dicated Myanmar as a likely origin.

gems, Afghanistan, Panjshir Valley, beryl, emerald, iron, silver

This chapter summarizes and interprets results from joint geologic and compilation activities conducted during 2009 to 2011 by the U.S. Geological Survey, the U.S. Department of Defense Task Force for Business and Stability Operations, and the Afghanistan Geological Survey in the Panjsher Valley emerald, iron, and silver area of interest (AOI) and subareas. The complementary chapters 13B and 13C address hyperspectral data and geohydrologic assessments, respectively, of the Panjsher Valley emerald, iron, and silver AOI. Additionally, supporting data for this chapter are available from the Afghanistan Ministry of Mines in Kabul. The emerald deposits of the Panjsher Valley are the main site for mining gemstone-grade emerald crystals in Afghanistan. The geology of the Panjsher Valley consists of Middle Paleozoic metamorphic rocks represented by a Silurian–Lower Carboniferous marble and Lower Carboniferous and Upper Carboniferous–Lower Permian terrigenous schist. Intrusive rocks include small bodies of gabbro diorite and quartz porphyry and a large intrusion of gneissic granite of the Laghman Complex. The area has an imbricate-block structure elongated to the southwest and northeast. Multiple tectonic events are related to structures within and parallel to the regional-scale Hari Rod fault system. Emerald mineralization in the Panjsher Valley AOI is genetically related to the Laghman Granitoid Complex and is controlled by elongated tectonic zones along the contacts between the carbonate and schist. The Panjsher Valley emerald district contains the following emerald occurrences from the west to east: Khinj, Mikeni I, Mikeni II, Rewat, and Darun. The Buzmal’ Mine is located to the north, close to Panjsher Valley. There are three types of emerald mineralization: (1) mineralization within or adjacent to tectonized diorite dikes (parts of the western zone containing the Buzmal’, Khinj, and Rewat emerald occurrences); (2) mineralization within shear fractures in schist (locality in the eastern zone containing the Darun, Khinj, and Mikeni I and II emerald occurrences); and (3) mineralization in or adjacent to hydrothermally altered and albitized quartz porphyry dikes.

gems, spectroscopy, advanced instrumentation, Raman specrometry, gemology

The current paper gives an overview of the development of Raman spectrometry in gemmological laboratories. While before 1990s, no commercial gemmological laboratory possessed such an instrument, all larger international labs have acquired these instruments by now. The Raman spectrometer is routinely used for the detection of emerald fillers, HPHT treatment of diamonds, analysis of the nature of a gemstone, analysis of gemstone inclusions and treatments, and the characterisation of natural or colour enhanced pearls and corals. Future developments in gemstone research lie in the closer analysis of the features of Raman and PL spectra and in the combination of several instruments.

corundum, geology.11, gems

Colored gemstones such as ruby, sapphire, emerald, and Paraíba-type tourmaline may achieve higher prices when associated with a specific geographic pedigree. Therefore, dealers and collectors increasingly turn to gemological laboratories for country-of-ori-gin analysis. To determine provenance, a laboratory must be knowledgeable about the gems’ geologic formation conditions and types of host rock, crystal growth features, and mineralogical and gemological properties. When the geologic conditions of the primary rock are very similar among several different localities, however, the gemstones’ properties may overlap, rendering origin determination difficult or impossible. Laboratories must meet this complex challenge by extending their observations and analytical capabilities to identify multiple features that yield diagnos-tic patterns to distinguish between similar sources.

corundum, geology.11, gems

Whereas diamonds are mined by large international companies and cut and marketed through a well-established distribution net-work, most high-value colored stones are extracted by independent miners or small companies and sold through less-organized channels. Exploration and grading protocols for ruby, sapphire, emerald, tsavorite, tanzanite, and alexandrite are virtually nonexistent due to the lack of intense research efforts or standardized values on the international exchange. Grading the quality of diamonds on the basis of the 4Cs (color, clarity, cut, and carat weight) is universally accepted and there are virtually no prove-nance-dependent variations in commodity value. With colored stones, though, geographic origin is an important factor for deter-mining price.