Burma.12, corundum, ruby, inclusions.5, gems

inclusions, gems

Burma.12, corundum, ruby, inclusions.5, gems

Eppler examines inclusions observed microscopically in Burmese ruby and discusses their value for characterizing the material. Illustrated with nine figures, the paper describes characteristic internal features, including mineral inclusions and growth-related structures, and considers their appearance and identification under the microscope. Particular attention is given to features useful in recognizing natural Burmese ruby and understanding its formation, demonstrating the importance of inclusions both as diagnostic gemological evidence and as indicators of the geological environment in which the corundum crystallized.

gems, jade, jadeite, fei cui, Mesoamerica, Mexico, Guatemala, Costa Rica, Mayans, Olmecs, Aztecs, archaeology, history, archaeogemology

Up to the present, the only jadeite deposits known in Mesoamerica are located north of Manzanotal, a settlement situated east of San Cristóbal Acasaguastlán in the middle course of the Motagua River Valley (Foshag and Leslie 1955; Barbour 1957). New deposits were discovered by E. Böse during a period of geological studies carried out in the region and were visited by the authors in July 1965. Most of these albite and jadeite deposits are located north of the paved Guatemala–Puerto Barrios highway, between the El Cintillo and Uyús rivers (see Figure 1), occurring as tectonic inclusions of varying dimensions within outcrops of foliated serpentinite. Becquelin and Bosc describe newly identified albite and jadeite occurrences near San Cristóbal Acasaguastlán in Guatemala’s middle Motagua Valley, where the deposits occur as tectonic inclusions of varying dimensions within foliated serpentinite. The authors report shallow pits surrounded by angular fragments of albite and jadeite, small mounds, terraces, and nearby obsidian blade fragments, which together suggest rudimentary extraction, possibly in prehistoric times, although they stress that further investigation is required to establish the nature and age of the workings. Other jadeite occurrences in the region lack evidence of ancient exploitation. The archaeological evidence from nearby Guaytán, Manzanotal, and other middle Motagua sites includes jade fragments, partly worked beads and drills, and a jadeite block bearing percussion marks. The authors suggest that inhabitants of the valley collected albite and jadeite from terraces and gravels of the Motagua and perhaps directly from serpentinite sources, manufactured beads and other simple ornaments, and exported jade as blocks and, in some cases, finished objects. They conclude that exploitation and trade in jade probably flourished during the Classic period and that the San Cristóbal region may have supplied a substantial portion of the jade used elsewhere in Mesoamerica.

corundum, sapphire, ruby, history.1, quality.10, gems

Bank presents an illustrated survey of gemstones, introducing their chemical and physical properties and explaining how these characteristics relate to identification. Individual gem materials are arranged according to mineralogical classification, linking their descriptions to the broader study of minerals. The text discusses inclusions and other diagnostic features, while locality maps provide geographical context for the occurrences described. Colour photographs form a major part of the presentation, allowing readers to appreciate the appearance and variety of gem materials alongside the scientific account. The work combines introductory explanations with information intended for readers already familiar with gemmology, serving as a general reference and visual survey. Its treatment of testing is selective, with less emphasis on absorption spectroscopy, and the individual descriptions do not consistently supply refractive-index and specific-gravity values. E.H. Rutland’s English translation makes Bank’s German account accessible to an English-speaking readership.

gems, ancient gems, glyptic, archaeology, archaeogemology, Ethiopia, Red Sea, Eritrea, olivine basalts, geology, analytical

The island of Kod Ali is a small diatreme cone lying close to the Ethiopian coast at latitude 13° 57′ N, longitude 41° 49′ E. This volcanic structure, produced by geologically Recent volcanic activity, consists, almost entirely, of pyroclastic debris. Evidence of a liquid phase is confined to the thin veneers of markedly alkalic olivine basalt which coat many of the abundant gabbroic, pyroxenitic and lherzolitic fragments found on the island. As silicic inclusions are completely absent and as the alkalic liquid phase and the “tholeiitic” inclusions are seemingly genetically unrelated, it is proposed that the latter might have been derived from a tholeiitic plutonic layered sequence that underlies the tholeiitic basalts of an “oceanic” Red Sea floor.

corundum, India.12, ruby, sapphire, history.1, gems, Indian lapidary

Sinkankas: Gemstones as viewed by an Indian author steeped in traditional lore presents a perspective deeply rooted in India’s enduring cultural relationship with gems, much of which remains seriously regarded today. As noted in a review in Gems & Gemology (Vol. 14, No. 2, 1972, pp. 61–63), the work is a unique combination of Indian culture and gemology." The lengthy and valuable introduction offers insights into Indian gem lore, tracing its origins to ancient texts as well as to more recent sources, many of which are cited by the author, Tank, along with the names of their authors. Topics discussed include the critical importance of imperfections in gems, distinctions between synthetics and naturals, and traditional Indian classifications, listing 84 gemstones in total. At the heart of the book is a focus on the nine traditional gems—emerald, diamond, pearl, coral, zircon, blue sapphire, sapphire, ruby, and cat’s-eye—shown on the color plate preceding the text. These are described using both traditional beliefs and modern scientific knowledge, with an emphasis on the qualities a gem must possess to be considered protective or influential. Tank also explores various gem varieties, their sources, and recommendations for when and where they should be worn for their protective powers. For instance, in the case of pearls, shape is crucial, and over 20 forms are illustrated with their Indian names. The book also includes synonyms for gems in different Indian languages and covers additional stones such as garnet, feldspar, quartz, opal, topaz, tourmaline, and beryl. It concludes with short notes on lapidary treatments and birthstones. Monochrome plates primarily depict cutting styles and one plate on inclusions. Unfortunately, and typically of much modern bookbinding in India, the physical binding is very poor—the spine is unrounded and the inner hinges tend to break upon opening. As noted in Rev/Gemm (Vol. 13, No. 6, 1973, p. 239), the book is not a scientific treatise."

corundum, inclusions.5, synthetic corundum.7, gems

Sinkankas: Typically written in simple, clear language and compiling articles originally published in Lapidary Journal, Oct. 1964–July 1968, with revisions. First 15 chapters on nomenclature, properties, crystallography, optical phenomena, color, inclusions, synthetics & imitations, testing procedures and instruments used, after which appear the remaining chapters on descriptions of gemstones, with organic materials treated in the last two chapters. The strong interest of the author in inclusions is apparent with much text devoted to same and hundreds of inclusion photographs; these form a most valuable part of the work. Rev. G & G, 13, 3, 1969, 103. Reprinted several times commencing in 1970.

corundum, synthetic corundum.7, Kashan, gems

Describes the Kashan synthetic rubies produced by the flux-growth process and examines the features by which they may be distinguished from natural ruby. The material shows the color and general appearance of fine natural ruby, making recognition potentially difficult without careful examination. Particular attention is given to characteristic internal features associated with flux growth, including residual flux and distinctive growth structures, and to their value in separating the synthetic stones from natural corundum. The article emphasizes the gemological importance of recognizing these diagnostic inclusions as flux-grown synthetic rubies became commercially available. One of the first references to Kashan synthetic rubies

gems, beryl, emerald, Brazil, Colombia, China, Zimbabwe, Pakistan, Zambia, Madagascar, Mozambique, inclusions

Sinkankas: Very handsome, imaginatively designed book, with the unusual feature of the title being spread over three pages. Apparently this work was meant to be the first of a series of monographs on gemstone families but up to date (1988) no others have appeared. The first part treats emerald history, in the East, as known to Pliny, origin of the name, curious lore surrounding, famous emeralds, and the color and causes. The second part describes world emerald deposits with most space naturally devoted to the Colombian mines, type crystals, and a discussion of trapiche crystals. The third part provides property data, considerable detail on inclusions in emerald, doublets & imitations, and the methods of gemological investigation . Next appear four tables of constants of natural & synthetic emeralds, comparisons of emerald to other similarly-colored stones or imitations, and fluorescence of emeralds from various deposits. The bibliography, unfortunately, is replete with errors in contrast to the text which is relatively free of defects. The mostly high quality illustrations show natural specimens, minerals that could be mistaken for emerald, cut stones, a Russian postage stamp depicting Siberian emerald, jewelry set with emeralds, absorption spectra, and many photographs of inclusions but these last lack the quality of the other illustrations. Rev R K Mitchell, J Gemm, 11, 7, 1969, 272–3, notes errors in biblio & elsewhere.