corundum, Australia.12, quality.10, gems

Walda L. Scholler’s Anakie: The Sapphire Fields of Central Queensland—Australia, first published in 1985 and subsequently revised in 1986 and 1990, is an illustrated regional history of the sapphire-mining districts surrounding Anakie, Rubyvale, and Sapphire in central Queensland. Written and published locally, the book documents the development of one of Australia’s most important gemstone-producing regions, combining the history of sapphire discoveries and mining settlements with accounts of the people and commercial interests associated with the fields. The region’s recorded sapphire history began in 1873, when surveyor Archibald John Richardson discovered sapphire near Retreat Creek, west of Emerald. Subsequent discoveries and mining activity established a district internationally known for its corundum deposits, particularly blue, yellow, green, and parti-colored sapphires. The sapphire fields attracted prospectors, small-scale miners, merchants, cutters, and collectors, whose activities connected relatively isolated Queensland settlements with international gemstone markets. The book is especially interesting for its treatment of exceptional gemstones recovered from the fields. A description of the third edition identifies several notable stones, including the Golden Willow, Stonebridge’s Green, the Centenary Gem, and the celebrated Black Star of Queensland. The latter, a remarkably large star sapphire, became internationally famous through its acquisition by the Kazanjian brothers, Los Angeles jewelers and gemstone dealers. The same description indicates that the book discusses the brothers’ purchasing activities and their acquisition of other important Anakie gemstones, illustrating the influence of international buyers upon the marketing of Australian sapphire. This aspect of the local industry is particularly relevant to gemological trade history, since Australian rough sapphire became an important component of the material exported to Thailand for cutting, treatment, and international distribution. Contemporary gemological reporting confirms that, by the 1980s, Thai buyers were purchasing substantial quantities of sapphire directly from Australian mining operations, with heat treatment frequently employed to improve appearance. Although these broader trade practices provide context for Scholler’s subject, their treatment in the book has not been independently verified. The publication is of particular bibliographic and historical interest because it records a regional gemstone industry through the perspective of a local author, preserving information concerning mining settlements, notable discoveries, and personalities that might otherwise be dispersed among local records and oral traditions. The 1990 third edition comprises 112 pages and includes illustrations. A separate, later publication by Scholler, Images of the Anakie Sapphire Fields, Queensland (1993), was praised in a contemporary Journal of Gemmology review for its detailed historical research, particularly its extensive use of local newspaper accounts and documentation of miners and mining personalities. That review concerns the later book and cannot establish the precise contents of the 1985–1990 editions. Nevertheless, the documented subject matter of Anakie makes it a useful reference for the history of Australian sapphire mining, notable corundum discoveries, and the development of commercial connections between Queensland’s gemfields and the international gemstone trade.

tourmaline, gems

A comprehensive synthesis of tourmaline mineralogy and gemology, drawing on more than 2,500 publications and incorporating nearly 1,000 references. Dietrich examines nomenclature, crystal morphology and structure, chemical composition, and the relationships between chemistry, species classification, and physical properties. Coverage includes crystal habits, exceptionally large crystals, inclusions and intergrowths, causes of color, color patterns, pleochroism, luminescence, and the effects of heating and irradiation. Additional chapters address physical properties, laboratory synthesis, industrial applications, and recovery. The gemstone chapter discusses tourmaline’s historical use in jewelry and decorative arts, fashioning, and notable gems. Geological coverage considers occurrences and formation in igneous, metamorphic, and sedimentary environments, while an appendix lists important sources of mineral specimens and gem material worldwide. The work’s principal strength is its organized compilation and evaluation of a widely scattered literature, making it useful to mineralogists, gemologists, and collectors. Individual deposits receive limited treatment, however, and the locality appendix lacks references directing readers to detailed accounts.

gems, jade, jadeite, fei cui, Mesoamerica, Mexico, Guatemala, Costa Rica, Mayans, Olmecs, Aztecs, archaeology, history, archaeogemology, Pre-Columbian jade; Costa Rica; Maya; exchange; iconography, lapidary

Despite the recognized importance of the Guatemalan Highlands within Formative-period trade networks of Mesoamerica, relatively little research on this time period has been conducted in the region. Studies undertaken in the Gulf Coast Lowlands, the Southern Maya Lowlands, and the Pacific Lowlands have all yielded a variety of trade goods originating in the Guatemalan Highlands. Jade has been identified from the Manzanal–Acasaguastlán–Guaytán area, along with obsidian from El Chayal and San Martín Jilotepeque. While the actual source areas for these trade goods have been identified, very little archaeological research has been conducted either within these source regions or on the trade routes that connected them to other parts of Mesoamerica. Nevertheless, various foreign groups, and the trade opportunities they provided, are thought to have had a major influence on the cultures of the indigenous highland populations. Support for this hypothesis has most often been drawn from the Valley of Guatemala, particularly the site of Kaminaljuyú. The early appearance of mound construction, the erection of stelae, and the use of certain ceramic types have all been cited as evidence for the developmental importance of contact with foreign groups. Outside the Valley of Guatemala, however, relatively little is known about either the nature of foreign contact during this period or the effects such contact may have had on local cultures. This paper attempts to outline the evidence for Middle and Late Formative-period foreign interaction in two regions of the Guatemalan Highlands: the Valley of Guatemala and the Quiché Basin. Although the available evidence remains limited, it is used to examine the role that external contacts may have played in the cultural development of these two areas.

gems, diamond, antique diamond, table cut, India

In June 1983 a large, flat diamond of octagonal outline was shown to Miss Anna Somers-Cocks of the Victoria and Albert Museum, London, who suggested that it should be taken to the Geological Museum for further examination; the owner had wondered if it might be part of the ‘Great Table’ shown to the explorer Tavernier at Golconda, India, in 1642. We quickly assured him that this was unlikely in view of the convincing study carried out by Meen, Tushingham & Waite (1967) in Teheran in 1967. The study showed beyond reasonable doubt that the Darya-i-Nur diamond and a pink brilliant, both among the Iranian Crown Jewels, were derived from and comprise the major part of the Great Table shown to Tavernier. The history of the present important stone is not known before 1893, when the father of the present owner is reported to have had it in his possession during a visit to Paris.

gems, jade, amphibole jade, nephrite, dyed nephrite

The Los Angeles laboratory examined a translucent to opaque pale green and brown carving of two birds, measuring approximately 23.4 × 7.2 × 9.5 cm, which testing confirmed to be nephrite jade. The brown coloration, especially concentrated in the shallow carved depressions such as the wing areas, appeared unnatural and suggested artificial staining meant to accentuate carved details. While rubbing a brown area with an acetone-soaked swab yielded no color transfer, a subsequent test using a 10% hydrochloric acid solution did produce a light brown stain, indicating the presence of dye or stain not removable by acetone. Based on the localized application and the unnatural color distribution, it was concluded that the carving had been artistically stained, a practice commonly observed with nephrite carvings. The gem identification report accordingly stated: NEPHRITE JADE, with some areas of artistic staining.

gems, opal, common opal, East Africa, Tanzania

Chrysoprase, the nickel-bearing green variety of chalcedony, has long been valued as a gem material, but its visual similarity to green nickel-colored opal (known as prase opal) has received little attention in the literature. Prase opal from Poland, Tanzania, Australia, and Peru has only been briefly mentioned in past studies. In light of this, the authors undertook a gemological investigation after receiving several samples of nickeliferous opal, particularly from Tanzania. These opals closely resemble chrysoprase in color and display similar diaphaneity, ranging from very translucent to semitranslucent. Both materials are commonly found in association with a brown limonite matrix in the rough, further increasing the potential for confusion. Given this strong likelihood of misidentification, a detailed gemological, chemical, and X-ray analysis of the opal was conducted, with results presented in the study.

jade, nephrite, New Zealand, gems

Sinkankas: Described by Henry Devenish Skinner, Director Emeritus of the Otago Museum, as “the most authoritative book ever written on New Zealand nephrite and bowenite” (p. 7), this work covers all aspects of the subject. Topics include the definition of Māori terminology; the history and legends associated with jade; the locations of nephrite, bowenite, and serpentine deposits, both alluvial and in situ (accompanied by maps); the origin and properties of nephrite; methods of jade working employed by the Māori and by modern craftsmen; and practical advice for contemporary jade workers. The book is richly illustrated, with numerous photographs depicting different jade varieties under both reflected and transmitted light, artefacts, jade boulders, landscapes of the jade-producing regions, and views of modern lapidary workshops. The history of modern jade working in New Zealand is also thoroughly covered. Reviewing the work in the Journal of Gemmology 12(8), 1971, pp. 363–364, Michael O’Donoghue remarked that “the coloured illustrations are particularly meritorious.” A further review appeared in Gems & Gemology 13(3), p. 84.

beryl, synthetic beryl, emerald, gems

Recently submitted to both the Los Angeles and New York offices of GIA'S Gem Trade Laboratory, Inc., were several faceted examples of a sophisticated type of synthetic emerald. The stones resemble in many ways synthetic emeralds of Russian hydrothermal manufacture that were recently obtained by Mr. Thomas Chatham in Hong Kong (see figure 2) and generously provided by Mr. Chatham to the Los Angeles lab for research.

corundum, properties.3, gems

The Alpha-Test electronic gemstone identifier is evaluated as a thermal-probe instrument capable of assisting identification of diamonds, diamond simulants and selected coloured gemstones. Its operation is compared with that of the earlier Gemtek Gemmologist. Both instruments measure the time taken for a heated probe tip to cool between two predetermined temperatures after contact with a gemstone; lower readings indicate faster heat removal. Because thermal differences among non-diamond materials are comparatively small, repeatable measurements require a draught-free environment at 18–25 °C, a stone first warmed to body temperature, and controlled probe pressure with the tip perpendicular to the tested surface. The Alpha-Test simplifies operation through automatic display resetting and thermostatic regulation of probe temperature, with a ready indicator and an off-scale warning above its maximum numerical reading of 999. Separate sapphire and emerald calibration adjustments provide two-point calibration across the measuring range. A permanently attached probe is identified as a servicing disadvantage because damage would require returning the complete instrument. Following calibration with sapphire and natural emerald, Read tested each specimen ten times and recorded average readings and their spread. Repeatability was better for materials with higher thermal conductivity: diamond, corundum, topaz, high zircon and spinel showed relatively narrow spreads, whereas lower-conductivity materials produced substantially wider variation. The author stresses that repeat measurements on one specimen do not represent the full range expected among different stones of the same species. The instrument is considered particularly useful for diamonds and their simulants, and for very small mounted coloured stones that cannot readily be examined with a refractometer or reflectivity meter. With care, useful separations include ruby from garnet, sapphire from tourmaline, and natural emerald from some flux-grown synthetic emeralds. Natural and synthetic spinel give appreciably different readings, while high and low zircon differ markedly. However, readings for topaz, high zircon and natural spinel overlap too closely for reliable differentiation. The report therefore presents thermal testing as a practical supplementary method whose value depends on controlled operating conditions and sufficient separation between the thermal responses of the materials under consideration.

corundum, synthetic corundum.7, Seiko, floating zone, gems

Floating-zone crystal growth was first devel-oped in 1953 to produce high-purity silicon as a semi-concluctor. It has since becn used to produce refractory mctals, alloys, and other sen~iconductingcompounds. Although colorless synthetic sapphire has been grown by this method in the past, it was not until thc Suwa Seikosha (SeikoWatch)Company Ltd. of Japan, became involved, as part of their efforts to make a better elec-tronic crystal for their watches, that this technique was developed to produce synthetic gems. 111 thc floating-zone crystal growth process, a sin-tcrcd rod, composed of a uniform mixture of all of thc coinponcnts necessary to producc thc dcsired gcin material, is held vertically at both thc top and bottom. An infrared radiation convcrgcnce heater, using a halogen lamp and an ellipsoidal reflector with its inncr surfacc gold plated, hcats a small region ncar the top of thc rod until it melts. The two holdcrs thcn bcgin to rotate whilc at the same timc the hcat source begins dropping down the rod at an cvcn rate. Eventually, the sintered rod is consunled and a single crystal results.