jade, jadeite, fei cui, Burma, gems

Jadeite may be white, pink, lilac, brown, red, orange, blue, black or many shades of green, and contains different trace elements as colouring agents. Of these trace elements, iron shows the highest concentration and its oxidation states of ferrous or ferric iron produce different colours. In white jadeite nearly all iron is present as ferric (trivalent) iron, while in black jadeite half is ferrous (divalent) and half ferric. In the leaf green jadeites the Fe2+ /Fe3+ ratio ranges from 0.1 to 0.2. The finest green Burmese jadeite, whose colour is caused by up to 0.3 per cent chromium, has been called Imperial jade' or 'emerald jade'. Contents of iron (up to 0.6% Fe) and nickel (0.04% Ni) can modify the rich chromium green of the jadeite. Lilac, mauve or lavender jade may contain manganese (up to 0.01% Mn), cobalt (up to 0.001% Co), chromium (up to 0.001% Cr) and iron (from 0.006 to 0.3% Fe).

corundum, quality.10, gems

Reviews conflicting accounts of the discovery and recovery of the Cheapside Hoard, a collection of approximately 340 jewellery items unearthed in London in 1912, and combines this historical investigation with descriptions of exceptional gemstones and workmanship. The hoard is interpreted as the stock of a Jacobean goldsmith, pawnbroker or dealer, buried under unknown circumstances in the early seventeenth century. Gosling compares museum catalogues, historical studies, newspaper tributes and recollections that disagree over the precise location, date, container and manner of recovery. Reports variously describe a decayed wooden box, a bucket, or jewels embedded in lumps of clay, while the absence of a direct account of the actual excavation prevents a definitive reconstruction. Central to the story is G.F. Lawrence, known as “Stony Jack”, whose relationships with building labourers enabled him to recover archaeological objects for London museums. Accounts portray him purchasing finds from workmen and receiving successive deliveries of clay-encrusted jewellery at his Wandsworth premises. The article highlights both his contribution to preserving the hoard and the unresolved details surrounding ownership, payments and Treasure Trove claims. Institutional disputes delayed agreement until 1916, when the collection was divided principally between the London and Guildhall museums, with smaller holdings elsewhere. Their later amalgamation reunited most of the material in the Museum of London. Gemmological notes describe a watch enclosed in Colombian emerald, identified by characteristic multiphase inclusions; a table-cut diamond estimated at three to four carats with a modified scissors-cut pavilion; and a hexagonal sapphire displaying rutile silk, pronounced growth zoning and an unusual combination of crown facets and a stepped pavilion. The sapphire’s appearance and setting are compared with those of the Stuart Sapphire. Amethyst and emerald grape pendants illustrate sophisticated lapidary methods, apparently involving intersecting annular drillings followed by removal of intervening material and rounding of the exposed ends. Gosling also considers how damp clay beneath a chalk cellar floor could explain decay of the container and dispersal of its contents. He concludes that the surviving uncertainties justify a new authoritative illustrated catalogue and consideration of further reunification of the collection, while recognising its importance as evidence of Elizabethan and Jacobean jewellery, gem cutting and material culture.

gems, beryl, emerald, phenakite, chrysoberyl, alexandrite, plagioclase, chlorite, and phlogopite, Urals, Russia

gems, beryl, emerald, Colombia

For over 1,000 years, the emerald deposits of Colombia have been the principal source of the world's largest and finest gem-quality emeralds—a variety of beryl containing chromium and vanadium1. Whereas most emerald deposits are found in association with igneous host rocks1, the Colombian deposits occur in organic-rich black shales, and their origin in the absence of any evidence of igneous activity has been a persistent enigma. Here we present evidence from the Muzo mine (located about 100km from Bogotá) that hydrothermal brines transported evaporitic sulphate to structurally favourable sites, where it was thermochemically reduced. We suggest that the sulphur generated by this process reacted with organic matter in the shales to release trapped chromium, vanadium and beryllium, which in turn enabled emerald formation.

corundum, inclusions.5, gems

Examines the scientific basis, practical requirements and limitations of determining the geographical origin of gemstones, emphasising that locality names should describe provenance rather than colour or quality. Hänni distinguishes a gemstone’s deposit of origin, whether primary or secondary, from commercial associations attached to names such as Myanmar, Kashmir or Pailin. Deposits produce variable material, and visually similar stones can occur in different regions; consequently, appearance alone cannot establish origin. Reliable attribution requires characteristics that support a proposed source while excluding alternatives, preferably through at least three independent diagnostic features involving inclusions, spectroscopy and trace-element composition. The paper relates such characteristics to the conditions of crystal formation, including available constituents, growth rate, fluid chemistry, oxidation state, temperature, pressure and deformation history. These processes influence growth zoning, twinning, colour distribution, mineral and fluid inclusions, healed fissures and trace-element patterns. Methods reviewed include microscopy in air and immersion, microthermometry, ultraviolet–visible and infrared spectroscopy, energy-dispersive X-ray fluorescence, electron-microprobe analysis, scanning electron microscopy, Raman spectroscopy and magnetic-resonance techniques. Their complementary roles range from documenting internal structures to identifying enclosed minerals and measuring chemical differences among gemstone populations. Particular importance is assigned to comprehensive reference collections of securely sourced specimens, analytical records, geological information and current literature. Ideally, comparison material should be collected directly from deposits; where this is impossible, reliable museum or historical collections may provide alternatives. Reference collections must represent variation within individual sources as well as differences between them. Examples demonstrate that features once regarded as exclusive can lose diagnostic status: three-phase inclusions formerly associated principally with Colombian emeralds also occur in material from Australia and Nigeria, requiring additional chemical evidence. Attribution is restricted when stones lack diagnostic features, properties overlap among deposits, jewellery settings obstruct examination, source information is inadequate or heating has destroyed useful evidence. Political borders may divide geological deposits, while individual countries may contain several distinct sources, complicating the wording of conclusions. Origin determinations therefore remain expert opinions expressing the most probable interpretation of available evidence. Their reliability depends on equipment, experience, continually revised reference data and prudent interpretation. Where observations are insufficient or ambiguous, the author argues that a definite origin report should not be issued.

gems, beryl, emerald, Egypt

Grundmann and Moretani provide a historical, mineralogical, and geological study of Egypt’s ancient emerald-mining district, concentrating on Zabara, Sikait, and Umm Kabo in the Eastern Desert. They review ancient references to Egyptian emeralds and the history of exploration and rediscovery of the workings, while noting the confusing nomenclature applied to the individual mining localities. The authors describe extensive ancient excavations and settlement remains and discuss evidence for mining over a long period, including Pharaonic, Ptolemaic, Roman, and later activity. Detailed geological sections examine the emerald occurrences within the Precambrian metamorphic complex, particularly their association with mica and biotite schists, serpentinites, talc-carbonate rocks, granitic and pegmatitic bodies, and structurally controlled zones of deformation and fluid activity. The three principal localities are treated separately, with descriptions of their mineral assemblages, host rocks, emerald-bearing zones, and proposed processes of emerald formation. The authors emphasize the importance of tectonic structures and hydrothermal or metasomatic processes, with beryllium-bearing fluids interacting with chromium-bearing rocks to produce emerald. Numerous maps, geological diagrams, photographs of the mines and workings, and photographs of emerald specimens illustrate both the archaeological and mineralogical aspects of the deposits.

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

We know that in the most advanced civilizations jade was used for ceremonial and ornamental objects; the characteristic most admired was its hardness, which best served artistic expression, together with its ability to receive and retain a lustrous polish (Foshag 1954:3). Jade was a stone of particular significance to the people of pre-Columbian Mesoamerica, for whom it was “the precious stone of grace, the first infinite grace, its green colour forming an allegorical metaphor for young maize, flowing water, and life itself” (Thompson 1950). In Group A-IV-1 at Kaminaljuyú, during excavations carried out in 1990 and 1991, a small but important assemblage of greenstone artefacts was recovered (Figure 1). Apparently, the first European contact with the material occurred in the sixteenth century through specimens brought back by the Spanish, rather than, as might be assumed, through contact with China (Foshag 1957:2). The word jade was coined in France as a derivation of the term piedra de ijada (“stone of the flank”), used by Spanish chroniclers to refer to this green stone arriving from the Americas, to which medicinal properties against kidney ailments were attributed (Hammond et al. 1977:38). By the time of the Conquest (Foshag 1954), several types of jade were distinguished among the Aztecs: chalchihuitl, which could be translated as “green-grass jewel stone,” referring to ordinary jade; quetzalitli, named after the iridescent green tail feathers of the quetzal, probably denoting the finest translucent emerald-green jade; tlilayutic, which may refer to dark chloromelanite; and white chalchihuitl, which appears to have been albite-jadeite. In addition to the identification of different qualities of the mineral, there is evidence of a preference among the elite for the finest-quality jades, a pattern that can also be traced back to Preclassic groups. With the Spanish conquest and the replacement of indigenous cultures, the use and knowledge of jade disappeared; along with it, the associated folklore was also lost.

gems, garnet, grossular, hessonite, India, Orissa, tourmaline, sillimanite

The state of Orissa in eastern India has emerged as an increasingly important source of gemstones. Since 1989, rising quantities of rhodolite garnets from the region have been seen, followed by notable finds of aquamarine and ruby. At the 1993 Tucson Show, Amar J. Jain presented a 2.99 ct faceted alexandrite and dark grayish blue tourmalines from Orissa, one of which—a 1.74 ct emerald-cut specimen—showed gemological properties consistent with tourmaline from other locations, including refractive indices of 1.620 and 1.640, birefringence of 0.020, and specific gravity of 3.11. Hessonite (grossular) garnet is also being mined near Kanta Bhaji in the Kalahandi area, with faceted stones ranging from reddish orange to orangish brown; many exhibit a pronounced “roiled” appearance typical of Sri Lankan hessonites, sometimes resembling translucent sard. A 2.19 ct orange stone tested with an R.I. of 1.748 and S.G. of 3.65, confirming it as hessonite. Following the show, the editors received a report from Shyamala Fernandes of the Gem Testing Laboratory in Jaipur describing a December 1992 find of chatoyant sillimanite, initially misidentified and marketed as “moonstone cat’s-eye.” Identified as sillimanite, the material exhibited an R.I. of 1.659–1.678 (1.66 spot), S.G. of 3.25, biaxial optic character, and Mohs hardness of 7–8. Microscopy revealed parallel acicular inclusions responsible for the chatoyancy, along with “fingerprint” two- and three-phase inclusions and black platelets. The sillimanite occurs in colors ranging from colorless to gray, pinkish brown, yellow, green, and blue-green, typically in lighter tones, and most cabochons—some up to 20 ct—display sharp cat’s-eyes and a vitreous luster. Though precise production data is lacking, the material has been readily available in Indian markets since its discovery.

gems, beryl, emerald, Colombia, drug wars

María Victoria Uribe Alarcón examines violence and the organization of power in the emerald-producing region of western Boyacá, Colombia. She explores how competition over emerald wealth, family loyalties, blood revenge and shifting alliances sustain armed conflict where state authority is weak. Particular attention falls on how enemies are defined and why peace agreements between leaders may fail to end hostilities among their followers. The study connects the emerald economy with broader questions of private power, social fragmentation and negotiated peace.

gems, inclusions, beryl, emerald, Madagascar