gems, jade, archaic jade, China, Chinese jade carving, nephrite, amphibole jade, cong, hsuen chi

For many years after its publication in 1912 Berthold Laufer's boo Jade : a study in Chinese archaeology and religion remained a standard referen work for Western scholars. In his third chapter Laufer discusses certain three-lobed jade discs (pl. I); he is in general agreement with the theories of the late-nineteenth-century Chinese scholar Wu Ta-ch'eng, who named the discs hsiian chi and suggested that they were origina intended to be used for astronomical purposes. After Laufer the discussion was taken up by other writers on jade, and was carried a stage further in series of papers by Henri Michel, beginning in 1947, in which he presented considerable amount of literary and scientific evidence in support of his interpretation of the astronomical purpose of the discs. Michel's theories were lent additional weight and given a wider circulation by their inclusion in Joseph Needham's survey of Chinese astronomy. Since Michel, those writers who have doubted the astronomical connexions of the discs have nevertheless tended to retain the name hsian chi, which now seems to have become established as the standard term for this particular jade form on museum labels and in archaeological reports in China as well as in the West.

corundum, Thailand.12, gems

The Tertiary Bo Phloi Basalt crops out in the area of approximately half a square kilometer, in the vicinity of Amphoe Bo Phloi, Kanchanaburi Province. It overlies quartzite of the Bo Phloi Formation of Silurian Devonian age. Generally, it is dark, dense, fme-grained and porphyritic. Megacrysts of clinopyroxene, black spinel and sanidine are commonly present. Ultramafic (spinel/peridotite/lherzolite) nodules or inclusions with varying size as well as xenoliths of gneissic rock, are frequently observed.

corundum, synthetic corundum.7, flux, Knischka, gems

Gunawardene examines the gemmological and crystallographic characteristics of the newly developed Knischka synthetic ruby, produced by Paul Otto Knischka of Austria using a modified gradient-transport technique involving supercooling and supersaturation. The paper describes the unusual crystal morphology of the material, including the development of numerous additional crystal faces, and compares these forms with those of natural corundum. Particular attention is given to microscopic identification. Characteristic internal features include turbid clouds, swirls of colour, liquid or feather-like patterns, negative crystals associated with elongated crystalline tubes, metallic platelets, melt residues and two-phase inclusions. Although some inclusions can resemble features in natural ruby or other synthetic rubies, their morphology and associations provide useful criteria for recognizing Knischka material. The study emphasizes microscopy as the principal means of identification and illustrates the diagnostic inclusions and crystal-growth features in detail.

corundum, Sri Lanka.12, inclusions.5, gems

Duyk describes an unusual 51 ct sapphire cabochon, apparently from Sri Lanka, containing two conspicuous internal cavities with well-developed crystalline outlines. He examines the morphology and optical appearance of these voids and discusses their relationship to the host sapphire, illustrating the features with nine photographs. The observations show that apparently empty, crystallographically shaped cavities can occur as internal features in natural sapphire and may provide useful evidence concerning the stone’s growth history.

gems, beryl, emerald, Zambia, inclusions

This article reports the identification of tourmaline crystals as inclusions in emeralds from Zambia, in south-central Africa. To under stand the paragenesis responsible for this unusual association, the geology of the area is reviewed. The gemological properties of these emeralds are also noted.

diamond, inclusions, gems

Gübelin examines mineral inclusions in natural diamonds as evidence for the conditions and processes of diamond formation in the upper mantle. He distinguishes two principal inclusion assemblages: an ultramafic suite characterized by chromium-bearing olivine, chrome-pyrope garnet, enstatite, chrome diopside, and chromite, and an eclogitic suite characterized particularly by pyrope-almandine garnet and omphacitic clinopyroxene, with rarer coesite, corundum (ruby), rutile, kyanite, and ilmenite. Minerals of the two suites had not then been observed together in a single diamond, whereas several inclusions belonging to one suite may coexist, indicating distinct paragenetic environments. Their chemistry, morphology, and relationships to the enclosing diamond are used to argue that diamond and its inclusions crystallized at great depth under upper-mantle pressures and temperatures and that diamond did not originate in kimberlite during its subsequent ascent. Gübelin discusses experimental and mineralogical evidence for crystallization from carbon-bearing ultramafic or eclogitic melts or partially molten material, with H₂O- and CO₂-rich fluids and Fe-Ni-Cu-Co sulphides playing potentially important roles. Sulphide inclusions, particularly pyrrhotite, are considered in relation to possible reduction reactions capable of precipitating carbon as diamond, while trapped gases provide additional evidence concerning the diamond-forming environment. The preservation of nickel-rich pyrrhotite is interpreted as evidence of rapid cooling, and the survival of diamond during transport requires rapid ascent in kimberlitic eruptions. Photomicrographs illustrate characteristic inclusions of olivine, garnet, enstatite, chrome diopside, omphacitic clinopyroxene, chromite, coesite, ruby, rutile, biotite, sulphides, and even diamond within diamond. The latter demonstrate that diamond growth could occur in successive episodes rather than as a single continuous event. Gübelin concludes that mineral inclusions provide direct samples of the otherwise inaccessible environment in which diamonds formed and permit important constraints to be placed on their paragenesis, pressure-temperature conditions, growth history, and subsequent transport to the Earth’s surface.

corundum, inclusions.5, gems

Pinpoint illumination uses a highly flexible but extremely durable glass fiber-optic bundle that incorporates six easily interchangeable light wands of various shapes and cross-sectional thicknesses down to one millimeter in diameter. The wands are hand held and can be used to illuminate hard-to-reach areas in complex jewelry ino~intingsW. ith the pinpoint, ill~lmintaor, a gemstone can be examined from any angle; the light source is placed exactly where it is needed, minimizing glare and unwanted external or internal reflections.

peridot, St. John’s Island, Egypt, gems, Classical world, geology, inclusions

Hydrothermal origin of gem olivines from Zabargad Island (St. John), Red Sea, through the study of their inclusions. The conditions of deposit and nature of the fluid inclusions in olivine gems from Zabargad prove that all the minerals have crystallized by an hydrothermal process which affected the island's principal peridotite body. Circulations of hypersaline fluids at high temperature (750°-900°C) with abundant volatile elements (CO₂, N₂, Cl, S, H₂O), with low pressure (partial pressure of CO₂ between 0.4 to 0.8 kbar) caused mobilisation of the major elements contained in the peridotite ; the chemical composition of included minerals which appeared during the cooling of the brines demonstrates this. The same fluids as well as CO₂ satured silicate liquids, which chemical composition is similar to basaltic andesites, characterize « normal » olivines of peridotite. By comparison to fluid inclusions in olivines from Assab peridotite nodules (Erythrea), untouched by hydrothermal processes, we note, in olivines from Zabargad, the absence of carbonic fluids with high filling density (Assab pCO₂ = 7.5 to 8.3 kbar). Hydrothermal process responsible for olivine crystallization seems to be associated with whole tectonic and magmatic events connected with first stages of Red Sea opening.

gems, Arabic mineralogy, jewelry from the Middle East, ethnic jewelry

Development in the Kingdom of Saudi Arabia has progressed at an astonishing pace, and nowhere is this more evident than in the field of archaeology—an area the author argues holds the key to unlocking many of the mysteries surrounding Bedouin jewellery. In light of newly available information, the documentation and preservation of this cultural heritage is both timely and vital. *The Art of Bedouin Jewellery* by Heather Colyer Ross presents a clear and engaging exploration of the remarkable range of ornaments crafted not only for adornment but also as portable wealth. Beginning with a historical overview, Ross traces the diverse influences that have shaped this art form—from Vikings and Chinese artisans to ancient Etruscans and modern Asian cultures—while also offering a detailed look into the life and traditions of the Bedouin people, which give this jewellery its cultural context. With over 100 colour photographs, primarily taken by the author, the book serves as a comprehensive visual and textual catalogue of necklaces, bracelets, armlets, anklets, belts, headpieces, and more, found across the Arabian Peninsula. Regional styles, the silversmith’s techniques, and the materials used are thoroughly examined, and the inclusion of an extensive glossary and list of technical terms in both English and Arabic adds significant value. *The Art of Bedouin Jewellery* is not only a treasure trove for collectors, but also an indispensable resource for anyone seeking to understand the rich traditions and craftsmanship of Arabia.

corundum, synthetic corundum.7, gems

Single crystals of corundum attaining 5 cm across were synthesized from cryolite (Na₃AlF₆) flux by the seed rotation method. The effect of growth conditions such as growth temperature, temperature difference, baffle aperture, and rotation rate upon crystal perfection is discussed to clarify the optimum conditions required to obtain crystals of high quality, containing the minimum amount of flux inclusions. The external shape of the corundum crystals did not show a noticeable change, except that the edges became more rounded with an increase in rotation rate. Experiments to simulate convective flow in solution were carried out on two systems—water and water–saccharose—under conditions simulating those of flux growth. When a baffle plate with 20% aperture was used, the flow velocity reached a maximum.