corundum, inclusions.5, Australia.12, geology.11, gems

gems, inclusions, beryl, emerald, Madagascar

corundum, inclusions.5, gems

corundum, Pakistan.12, gems, spinel

An illustrated survey of Pakistan’s gemstones that relates their properties and occurrence to the country’s geological and tectonic setting. An introductory section explains gemstone composition, physical properties, identification instruments, cutting and polishing, and the acquisition of rough. Subsequent chapters organize the deposits by geological association, covering emeralds associated with the Indus suture, ruby and spinel in the crystalline marbles of the Hunza region, pegmatite minerals, and gemstones from hydrothermal veins. Detailed accounts include aquamarine, tourmaline, feldspar, quartz, and topaz, with particular attention to the pink topaz of Katlang. Pakistani emeralds are also compared with synthetic material. Maps, geological sections, tables, and color photographs connect descriptions of individual gems with their host rocks and regional environments. Photographs by E.J.Gübelin illustrate inclusions, while A.H.Kazmi contributes specimen and landscape images. Brief concluding sections address miscellaneous gem materials and Pakistan’s gem market. Intended partly to encourage further discoveries, the book provides an accessible geological foundation for prospectors, gemologists, jewelers, and collectors, supported by an extensive bibliography.

gems, beryl, emerald, inclusions, Brazil

quartz, inclusions, gems

feldspar, gems

Describes light blue to light green gem-quality feldspar from pegmatite dykes near Kioo, Kenya, approximately 13 km east of Sultan Hamud. The material resembles aquamarine in colour and has a vitreous lustre. Optical measurements, X-ray diffraction and electron microprobe analyses identify a sodium-rich plagioclase with a peristerite structure. Reported inclusions comprise distinctive growth irregularities, fingerprint-like patterns containing occasional two-phase inclusions, and vermiculite crystals. The article also outlines the geological setting, associated minerals and mining methods.

gems, inclusions, feldspar, orthoclase, moonstone, sunstone

Gübelin and Koivula examine feldspars both as gemstones containing inclusions and as mineral inclusions occurring within other gemstones. Using photomicrographs, they illustrate characteristic internal features of gem feldspars—including members of the orthoclase and plagioclase groups—and examples in which feldspar itself occurs as an included mineral. The article emphasizes the value of identifying such inclusions for understanding the geological environment and formation history of their host gemstones, while demonstrating the considerable variety of microscopic features associated with the feldspar group.

opal, Mexico, gems

Gübelin provides a historical and technical survey of Mexican opal, discussing the principal varieties and their major localities. He notes the use of opal in pre-Columbian Mexico and describes the important deposits in the volcanic regions of Querétaro and Jalisco, where opal occurs in cavities and fractures in rhyolitic rocks. Particular attention is given to Mexican fire opal, with its characteristic yellow, orange and red body colors, as well as transparent precious opal displaying play-of-color. The article discusses the appearance, occurrence and characteristic inclusions of Mexican material; later studies cite Gübelin for two- and three-phase inclusions and mineral inclusions including hornblende, goethite, hematite, fluorite, quartz, cristobalite and chalcedony in Querétaro opal.

beryl, synthetic beryl, emerald, gems, SEM

Hofmann, Schrader and Stender describe applications of scanning electron microscopy (SEM) to gemological research, emphasizing its usefulness for examining surface structures and extremely small features beyond the practical resolution of conventional gemological microscopy. Examples illustrate how the technique can reveal the morphology of inclusions, growth and dissolution features, fracture surfaces, and other microscopic structures relevant to gemstone investigation. When combined with electron-beam microanalysis, SEM also permits localized chemical characterization of minute inclusions or surface features. The brief article demonstrates the value of SEM as a complementary research technique where conventional optical microscopy alone provides insufficient morphological or compositional information.