corundum, Burma.12, gems

corundum, synthetic corundum.7, gems

The gemological, spectroscopic, and chemical characteristics of newly marketed Chatham flux-grown synthetic pink sapphires are documented through examination of four faceted stones weighing 2.73–4.19 ct and microscopic study of an 884 ct crystal. The material is essentially a lighter-toned counterpart of Chatham synthetic ruby. The faceted specimens are transparent, evenly colored, and medium light to medium purplish pink with fairly high saturation; the large crystal has comparable hue and saturation but a darker tone. Refractive indices are 1.768 and 1.759, birefringence is 0.009, and specific gravity ranges from 3.99 to 4.00. Dichroic colors are purplish pink and orange-pink. All specimens appear strongly red through a Chelsea filter and show absorption lines consistent with natural and synthetic ruby and pink sapphire. Long-wave and short-wave ultraviolet radiation produce essentially equally strong orange-red fluorescence with a weakly to moderately chalky overtone, without phosphorescence. This response differs from Chatham synthetic ruby, which generally fluoresces more strongly under long-wave radiation. Flux inclusions near the crystal’s surface fluoresce green, while deeper inclusions appear yellow, probably through combination with the host’s red fluorescence. Microscopic examination reveals primary flux inclusions ranging from large, granular masses to rows of minute droplets along growth steps. In two faceted stones, apparent primary flux particles form delicate intersecting rows producing a grid-like pattern, previously undocumented by the authors in synthetic gem materials and resembling arrangements of negative crystals in some natural spinels. Secondary flux inclusions occur as partially healed fingerprints, predominantly with undulating forms. Metallic inclusions include individual platelets, clusters of small rods and platelets, and dendritic formations; one stone contains a phantom layer of triangular and hexagonal platelets. Energy-dispersive X-ray fluorescence detects chromium, trace iron, and platinum in addition to aluminum. Platinum is attributed to the growth crucible and supports identification of the metallic inclusions. Chromium concentrations range from 0.027 to 0.200 wt.% Cr₂O₃, without an obvious relationship to specimen color, even after considering size differences. Most properties resemble those of other Chatham flux-grown corundums, while the ultraviolet response and unusual grid-like inclusions are noteworthy distinctions. Inclusions provide diagnostic evidence for separating these synthetic pink sapphires from natural material.

corundum, Kenya.12, gems

N.R. Barot and R.R. Harding describe a deposit of pink corundum in the eastern foothills of Mount Kenya and examine its geology, production, gemmological properties, and possible relationship to dyed corundum marketed through India. The Taawajah claim in northern Kitui lies within the Mozambique orogenic belt, where Precambrian basement rocks include quartzites, marbles, calc-silicate rocks, amphibolites, and gneisses associated with intrusive rocks. Pink corundum was recognized during prospecting in 1969, but development followed renewed surveying in 1988 and registration in 1989. Open-pit mining employs pneumatic drills, hand tools, washing, sieving, and manual selection, with a workforce of approximately 30–50. Reported weekly recovery generally ranges from 50 to 100 kg and occasionally reaches 200 kg. Most corundum occurs in shallow gravel, while deeper material remains attached to other minerals, suggesting a predominantly eluvial deposit derived from nearby rocks with some local reworking. Most production is exported to India; approximately 1–5% is considered good quality and is cut locally or sold to Germany. The translucent light to medium pink material is principally suitable for cabochons and beads. Examination of rough and polished specimens reveals reddish-pink colour, commonly complicated by red zoning, occasional blue areas grading through purple, iron staining, abundant fissures, twinning, and variably coarse rutile silk. Associated minerals include hornblende, feldspar, quartz, and micaceous material. Untreated specimens show moderate dichroism and orange-red ultraviolet fluorescence, weakened by increasing opacity or blue coloration. Electron microprobe analyses establish minor chromium and somewhat higher iron contents, while ultraviolet–visible spectra show no obvious features distinguishing the material from previously documented ruby and sapphire. The authors also investigate red-dyed cabochons and faceted beads obtained through India. Microscopy reveals patchy concentrations of dye along fractures, with fluorescence arising chiefly from these fissures. Treated cabochons have spectra closely resembling those of untreated Kitui corundum, making Kitui a possible source without establishing provenance. The dyed faceted beads differ spectrally and contain no detectable chromium at the stated analytical threshold; their source remains unknown. Water immersion produces no apparent dye loss, whereas organic solvents cause varying degrees of dissolution. Ethyl alcohol and amyl acetate are particularly effective for detecting dye in the beads through a pink residue transferred to white tissue, although cabochons with fewer fissures may require more persistent examination. The study documents a commercially productive source of cabochon-grade pink corundum and demonstrates the importance of fracture inspection and solvent testing when assessing strongly red material that may owe its appearance to dye.

corundum, synthetic corundum.7, gems

Three laboratory notes describe the production history, internal characteristics, and infrared examination of synthetic rubies encountered by the Asian Institute of Gemological Sciences. The Kashan note records Steve Ruyle’s acquisition of the remaining production assets associated with the synthetic ruby originally manufactured by F. Truehart Brown from the mid-1960s. Ruyle reported acquiring several furnaces, one of which was producing small quantities of Kashan-type material by what he described as a combination of flux and hydrothermal techniques. The stones actually examined were reportedly more than ten years old, so their characteristics document earlier material rather than establish the properties of the new production. Their colours ranged from pink through orangy red to deep purple-red. Microscopy revealed characteristic flux-filled feathers resembling twisted veils and isolated flux-filled cavities with forms previously likened to moccasin footprints, dog bones, or paint splashes. A second note examines two Russian synthetic ruby products attributed to different growth processes. The first was described as horizontally grown by a method combining aspects of pulling and floating-zone techniques, using a seed, a boat-shaped container of powdered constituents, and a moving tungsten heat source. Several heating passes reportedly produced a large crystal over approximately two weeks. The specimen examined weighed 2,817 carats despite being broken at one end, measured approximately 11 × 9 × 2 cm, and contained numerous gas bubbles together with dendritic crystal formations concentrated in its pointed end. The second product was reportedly made by combining Verneuil flame fusion and pulling techniques. Its 286.44-carat crystal, approximately 7 × 2 cm, had a roughly hexagonal seed-end outline and a rippled, silky exterior. Unlike typical Verneuil material, it appeared free of the usual bubbles; the only observed growth structures were fine diagonal lines. The final note reports Fourier-transform infrared examination of a previously described Russian hydrothermal synthetic ruby using a Nicolet Magna 550 spectrometer. Comparison with a natural ruby from Myanmar revealed distinct spectral differences across approximately 3800–2800 cm⁻¹, illustrated by pronounced absorption features in the synthetic specimen.

corundum, synthetic corundum.7, gems

A Russian synthetic ruby submitted in 1993 to the German Foundation for Gemstone Research is characterised by standard gemmological testing, microscopy, visible absorption spectroscopy, and chemical analysis. Although reportedly produced hydrothermally in Novosibirsk, the specimen is identified as a product of flux synthesis. The investigation is placed within the expanding supply of Russian synthetic gemstones following the political and economic changes in the former Soviet Union, with a table summarising materials and production methods previously reported from the region. Earlier Russian rubies had included both flux-grown and hydrothermal products. The examined crystal weighed 138 carats, had a boule-like shape, and was dark red, showing distinct purplish-red and orange-red pleochroism. Macroscopic examination revealed dark dendritic inclusions and a metallic coating over a small surface area. Measured refractive indices were 1.762 and 1.770, with birefringence of 0.008 and specific gravity of 4.00. Fluorescence was strong red under long-wave ultraviolet radiation and weak red under short-wave radiation. Immersion microscopy revealed opaque black flux residues with characteristic dendritic forms; dark-field illumination showed their polycrystalline nature. A second inclusion type consisted of clouds of bubble-like flux residues within partly healed cavities, resembling features described in Knischka synthetic rubies from Austria. Polarised visible absorption spectra displayed pronounced chromium-related lines and bands, including a line at 692 nm. Broad absorption maxima occurred at 545 and 409 nm for light polarised parallel to the crystallographic c-axis, and at 554 and 400 nm for perpendicular polarisation. Scanning electron microscopy with energy-dispersive X-ray analysis gave a composition of 98.61 wt.% aluminium oxide and 1.39 wt.% chromium oxide. Tungsten and molybdenum were detected in the metallic surface coating and in fractures where dendritic inclusions reached the surface. These flux-related elements and the diagnostic inclusion structures establish flux growth despite the reported hydrothermal origin. The physical properties and chemical composition otherwise fall within the ranges of synthetic rubies from other producers, making the microscopic and inclusion-chemical evidence central to recognising the material’s growth method.

corundum, Montana.12, USA.12, gems

Jade, Thailand, India, Cambodia, gems

Karen Schur Narula’s Voyage of the Emerald Buddha, published in Oxford University Press’s Images of Asia series, traces the legendary and historically documented movements of Thailand’s most revered Buddhist image, the Emerald Buddha (Phra Kaeo Morakot), now enshrined in Wat Phra Kaeo within Bangkok’s Grand Palace. Combining Buddhist chronicles, regional history, religious traditions, and art-historical observations, Narula examines the statue’s uncertain origins and its association with political legitimacy, royal authority, and the spread of Theravada Buddhism across South and Southeast Asia. The narrative begins with the royal ceremony in which Thailand’s monarch changes the image’s seasonal garments, describing its elaborate gold ornaments, including a jeweled headdress decorated with sapphires and a robe embellished with rubies. The author then introduces the Chronicle of the Emerald Buddha, a collection of traditions preserved in manuscripts from Thailand, Laos, and Cambodia. According to the legend, the image was created in India through the intervention of the Buddhist sage Nāgasena, assisted by Indra and the celestial craftsman Visukamma, who obtained a magnificent green stone from supernatural guardians. The statue was subsequently transported to Sri Lanka, Burma, Cambodia, and northern Thailand before reaching Laos. Narula emphasizes that this account contains substantial chronological contradictions and supernatural elements that prevent its acceptance as reliable historical evidence. The book’s successive chapters examine the histories of India, Sri Lanka, Burma, Cambodia, Thailand, and Laos, connecting the legendary itinerary with the development of Buddhist sculpture, religious institutions, political alliances, and commercial networks. Of particular gemological interest is the question of the statue’s material and geographical origin. Despite its conventional name, the Emerald Buddha is not fashioned from emerald. Narula identifies the material as jade and specifically suggests nephrite as a possible carving material, although the book provides no analytical evidence establishing its precise mineralogical composition. She considers possible origins in India, Sri Lanka, and northern Thailand, noting the influence of Gandharan, Amaravati, Sinhalese, and Lan Na sculptural traditions. The first securely documented appearance of the image occurred at Chiang Rai in 1434, when a stucco-covered statue was discovered inside a chedi, reportedly following a lightning strike. When the stucco subsequently flaked away, the concealed green stone was revealed. The image was transferred to Lampang, where it remained until 1468, and then to Chiang Mai. In the sixteenth century it passed into Lao possession under King Setthathirat, eventually reaching Vientiane in 1564. There it remained until Siamese forces under Chaophraya Chakri captured the city in 1778 and carried the image to Thonburi. Following the establishment of Bangkok as the capital of the Chakri Dynasty, King Rama I transferred the statue to its present shrine on 22 March 1784. Throughout the narrative, Narula stresses the image’s significance as a palladium whose possession was believed to ensure prosperity, religious protection, and legitimate sovereignty. Numerous photographs, historical illustrations, maps, and examples of Buddhist sculpture document the artistic traditions and monuments associated with its supposed travels. Although primarily a historical and religious study rather than a technical gemological investigation, the book provides useful information on the Emerald Buddha’s possible nephrite composition, uncertain provenance, stylistic characteristics, and the cultural significance of a monumental green gemstone carving within Southeast Asian Buddhism.

gems, Ceylon, Sri Lanka, musgravite, taaffeite

Demartin and coauthors report the first known musgravite to have been fashioned as a faceted gemstone. The specimen, a 5.74 ct greenish-grey stone reportedly from Sri Lanka, was initially submitted for identification as a possible taaffeite. Gemological, chemical and X-ray investigations identified it as musgravite, a rare beryllium-magnesium-aluminium oxide closely related to taaffeite. The authors describe its refractive indices, specific gravity, optical character, absorption spectrum and chemical composition, and compare these properties with those of taaffeite. The identification demonstrated that musgravite, previously known principally as a rare mineral species, can occur as transparent material of sufficient size and quality for faceting.

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

Considered by many scholars the finest extant Mexican codex and one of the most important original sources for the study of pre-Columbian religion, the Codex Borgia is a work of profound beauty, filled with strange and evocative images related to calendrical, cosmological, ritual, and divinatory matters. Generally similar to such Mixtec manuscripts as the Codex Nuttall, the Codex Borgia is thought to have its origin (ca. A.D. 1400) in the southern central highlands of Mexico, perhaps in Puebla or Oaxaca. It is most probably a religious document that once belonged to a temple or sacred shrine. One use of the Codex many have been to divine the future, for it includes ritual 260 day calendars, material on aspects of the planet Venus, and a sort of numerological prognostic of the lives of wedded couples. Another section concerns various regions of the world and the supernatural characters and attributes of those regions. Also described are the characteristics of a number of deities, while still other passages relate to installation ceremonies of rulers in pre-Columbian kingdoms. Until the publication of this Dover edition, the Codex Borgia has been largely inaccessible to the general public. The priceless original is in the Vatican Library and previous photographic facsimiles are very rare or very expensive or both. Moreover, the original Codex has been damaged over the centuries, resulting in the obscuration and loss of many images. In order to recapture the beauty and grandeur of the original, Gisele Diaz and Alan Rodgers have painstakingly restored the Codex by hand— a seven-year project — employing the most scrupulous research and restoration techniques. The result is 76 large full-color plates of vibrant, striking depictions of gods, kings, warriors, mythical creatures, and mysterious abstract designs — a vivid panorama that offers profound insights into pre-Columbian Mexican myth and ritual. Now students, anthropologists, lovers of fine art and rare books — anyone interested in the art and culture of ancient Mexico — can study the Codex Borgia in this inexpensive, accurate, well-made edition. An informative introduction by noted anthropologist Bruce E. Byland places the Codex in its historical context and helps elucidate its meaning and significance.

gems, jade, pyroxene jade, fei cui, Guatemala, Mesoamerica, Nicaragua, Mexico, Honduras, Costa Rica, archaeogemology, Cuba, Dominican Republic, Maya, Mayan, Olmec, Aztec, sculpture

Reviewing a work of Alfred Métraux in 1962, Claude Lévi-Strauss approved the author’s efforts to “demystify” the ancient Incas and to reinforce the standards of “austere science,” but he observed that nevertheless the Incas remained a mystery and indeed that all of Pre-Columbian America was like “a sort of planet Mars” (1962: 140). This statement is a bit jarring, coming as it does from the professional anthropologist whose stock-in-trade is usually presumed to be the process of demystifying, reducing strangeness, and narrowing cultural gaps. Certainly it marks a break with the tone of early twentieth-century anthropology, in which the assumption was current that once the prejudices imposed by Eurocentrism, colonialism, and racism were jettisoned, “understanding”—even across the barriers separating the modern and the Pre-Columbian worlds—would be the result. Lévi-Strauss’ scepticism about such a possibility marked yet another turn of the wheel in the long process of interpretation and reinterpretation that constitutes the history of the European encounter with and response to Pre-Columbian civilization. His remarks were one instance of a more general retreat from the claims of Western science (to objectivity, comprehensiveness, and boundless hermeneutic prowess) that was essential if the blinders created by the scientizing process itself were to be recognized. This paper—which examines some moments in the history of French and English collecting and exhibiting of Pre-Columbiana—is offered in the spirit of recent work in the history of anthropology that “observes the observer” in order to chart this growth in self-consciousness and reflexivity in what has come to be called the discourse of the Other (Stocking 1985: 3–14). Like a number of the papers here, it explores the changing cognitive and cultural frameworks that conditioned the search for and representation of the materials of Pre-Columbian civilization. The focus is on Europe, where rationales for Pre-Columbian inquiry developed that were quite distinct from American ideologies of hemispheric cultural identity (Hinsley and Barnet-Sanchez, this volume). The specific focus is on France and England, the two leading colonial powers of the nineteenth century and countries in which extensive Pre-Columbian collections were built despite hesitations, perplexities, and formidable material obstacles. The period treated is 1870–1930, an era of peculiar importance because it encompasses the development of “museum anthropology,” with its privileging of the study of objects rather than cultural or social processes, and because it includes the period of the dramatic aesthetic revaluation of Pre-Columbiana that accompanied the so-called primitivist revolution.