beryl, emerald, Colombia, Muzo, Coscuez, gems

The Muzo emerald district, in Boyacá, Colombia, contains several mines. Although the Muzo mine is undoubtedly the best known, the Coscuez mine is rapidly gaining significance as a major source of fine emeralds. Yet few in the trade outside of Colombia are aware of the importance of Coscuez or know about the emeralds mined there. The Coscuez mine is literally hundreds of years old, and its history is closely tied to that of Muzo. Located only about 10km apart,the two areas also share many geologic features and both are currently exploited using open-cut mining methods. The Cosccuez emeralds are similar to Muzo stones in their physical properties, but they occurin a somewhat broader range of hue and saturation. Prospects for even greater production at Coscuez in the future are good.

corundum, USSR.12, Tajikistan.12, Russia.12, gems, jade, nephrite, diamond, beryl, emerald, tourmaliine, aquamarinte, diopside, charoite, fei cui, jadeite

Sinkankas: The most comprehensive and authoritative treatise in modern times of the gemstones of the USSR, with good color photographs of cut & rough gemstones, countryside views, mining activities, etc., and all attractively designed and on good quality paper. Unfortunately, only the illustration captions are in English. p. 4: ‘This book includes detailed characteristics of the main species of gems and semiprecious stones in the USSR. Descriptions of geological, structural, genetic and other factors of the origin and distribution of gemstone formations are given. The territory of the country is divided into ore regions of gemstone raw materials with regard for main geological and structural and economic regions. Complex and monomineral provinces of gemstone raw material are marked out. The distinction and cutting of natural gemstones and their imitations are examined.’ In addition to the expected geological/mineralogical treatment as indicated in the foregoing resume, it should be noted that Part 6, on the history of the development of the manufacture of many types of articles from gemstones and stone, is especially rich in illustrations of all manner of articles from massive stone monuments, urns, etc., to articles of personal adornment, crown jewels of Tsarist days, peasant jewelry, small animal carvings, and many more. As noted by M. J. O’Donoghue in his review, J Gemm, 20, 4, 1986, 254–5, ‘there are many quality colour pictures and even for those with no Russian these make the book well worth getting.’ I have seen another issue of the present work, dated 1985, same price, bound in plain, olive-green cloth-type paper over boards.

gems, bery, beryl, emerald, inclusions, Brazil, Santa Teerezinha de Goiás

The Santa Terezinha de Goias emerald deposit, currently the most important source of emeralds in Brazil, lies northwest of Brasilia, in the State uf Goias. The emeralds, most of which are stones of a carat or Jess, occm in a talc schist layer intersected by pegmatite. The emeralds are recovered by independent miners via trenches, pits, and tunnels at two prospects: Trecho Novo and Trecho Velho. The grade of the ore is: l to 6 parts of emeralds to 10,000 parts of ore. The density of the gems is 2.70; the refrnctive indexes are 1.580 and 1.588, with greenish dark blue/yellowish pale green pleochroism. The spectrum is typical, with two strong lines and two partial absorption bands; there is no fluorescence; pyrite and chromite are the most typical inclusions, with calcite crystals present in minor amounts.

corundum, ruby, sapphire, inclusions.5, USA.12, Montana.12, Thailand.12, gems

A comprehensive monograph on the origin, occurrence, composition, physical properties, and geological significance of fluid inclusions in minerals, representing a major synthesis of research on fluids trapped during crystal growth and subsequent geological processes. Edwin Roedder examines the formation and classification of primary, secondary, and pseudosecondary inclusions, distinguishing liquid-rich, vapor-rich, multiphase, and solid-bearing varieties and explaining their relationships to mineral growth, fracturing, and recrystallization. Particular attention is devoted to the physical chemistry of geological fluids, including pressure–volume–temperature relationships, phase equilibria, salinity, density, and the behavior of aqueous and nonaqueous systems. The author describes techniques for investigating fluid inclusions, including petrographic microscopy, heating and freezing experiments, microthermometry, crushing-stage methods, and chemical analysis. Detailed discussions address homogenization temperatures, freezing-point depression, daughter minerals, gas bubbles, immiscible fluids, and the interpretation of fluid inclusion assemblages in reconstructing conditions of mineral formation. Applications encompass igneous, metamorphic, hydrothermal, sedimentary, and ore-forming environments, with emphasis on the determination of crystallization temperatures, pressures, fluid compositions, and the evolution of mineralizing solutions. Of particular gemological significance are the descriptions of fluid inclusion morphology, multiphase inclusions, negative crystals, healed fractures, and the distinction between inclusions formed during crystal growth and those introduced by later geological events. These principles are fundamental to interpreting inclusions in ruby, sapphire, emerald, quartz, topaz, tourmaline, and other gemstones, particularly in studies of geological origin and formation conditions. Numerous photomicrographs, phase diagrams, experimental data, and extensive references support the discussion. The volume remains a foundational reference for fluid inclusion petrography and microthermometry, providing both theoretical background and practical guidance for understanding the fluids involved in mineral formation and alteration.

gems, beryl, emerald, Colombia, emerald treatments, emerald oiling

It is well known in the trade that most emeralds on the market today are oiled. This article focuses on Colombian emeralds and gives a detailed explanation of the oiling process as observed by the author. Sophisticated laboratory procedures are compared with common back porch" methods. The methods used often vary from parcel to parcel, and the success of the treatment depends in part on the experience of the treater, although the process itself appears to be relatively permanent. Observations are also presented on methods of detecting oiling as well as on the use of colored oils."

gems, Islamic art, Islamic jewelry, Islamic gems, ruby, diamond, spinel, emerald, jade

In the mind even of the art-lover of the West, India’s Taj Mahal takes its place with the Parthenon and Chartres as one of the great monuments of human thought in stone; the smaller objects of the decorative arts contemporary with it have not so far been given equal attention. This book, with a foreword by Sir Roy Strong, is a lasting record of the exhibition organized by the Victoria & Albert Museum, London, which brought together nearly 600 of these artefacts made under the patronage of the Mughal dynasty and other members of the Indian nobility between 1526 and 1858. Ten scholars and experts in the field, headed by Robert Skelton, Keeper of the Indian Department of the Museum, contribute specialist essays or write detailed entries on each item in the exhibition, nearly half of which are illustrated here in colour or black and white. Separate sections cover architectural decoration, paintings and the arts of the book, carpets and other textiles, jewellery, glass and hard-stone carvings in jade, agate and rock crystal, arms and armour and other metalwork, coins and insignia, ivory and woodcarving. From them a general picture emerges of how the most refined craftsmanship was practised under the aegis of princes, maharajahs, and nawabs who were fabulously wealthy, and yet who prized a single flower as much as the richest gem in the pursuit of their ‘cult of the exquisite’. In this period the decorative arts in India took a new direction that was open to Renaissance as well as Near Eastern Islamic influences and, incidentally, came eventually in the nineteenth century to serve as one of the oriental sources of our own Arts and Crafts Movement in England, Europe, and America. Mughal art was eventually brought to an end by the influence of colonial European taste, and this is reflected in the late works. This is the first time that such a wide array of objects have been considered in their historical perspective.

corundum, inclusions.5, ruby, spinel, beryl, emerald, Pakistan.12, Afghanistan.12, chemistry.2, geology.11, gems, spinel inclusions

Only during the last few years have the gem riches of Pakistan become known to the rest of the world. This article reports on three gem materials currently being mined: emerald, corundum (most importantly, ruby), and spinel. Intensely colored emerald crystals occur in dolomitic talc schists in the Swat Valley. Unusually high optical properties and density serve to distinguish these emeralds from those found elsewhere. Numerous gas-liquid inclusions are also typical. In the Hunza Valley, specimen-and gem-quality crystals of corundum and spinel occur in beds of marble enclosed in gneisses and mica schists. The gemological properties of the Pakistan rubies and sapphires vary only slightly within normal limits.

gems, ancient gemology, ancient jewelry, Egypt, Egyptian jewelry, beryl, emerald, turquoise, malachite, Mesopotamia, Near East, glyptic, engraved gems, lapidary arts, ancient lapidary

Evidence for the products manufactured by stoneworkers in Mesopotamia in ancient times is, of course, best displayed by those objects discovered and subsequently ana­lyzed by archaeologists and, of late, by those individuals interested in certain tech­nical aspects of the production of these artifacts. However, those of us primarily interested in philological problems of the ancient world would like to think that the written records of the ancient Mesopo­tamians, fortunately recorded on durable clay tablets, can also provide some insight into the relatively mundane side of a com­plex society as exemplified by the economic records. The tablets, besides recording great works of literature, also provide us with ample evidence of day-to-day records of agriculture, animal husbandry, textile man­ufacture, shipping and other trade, regula­tion of work forces, temple activities, irrigation and distribution of rations, as well as the production of highly specialized luxury goods described mostly in terms of inventories of finished products. Occa­sionally, as in the texts I shall discuss, tablets describe the organizations respon­sible for the actual making of the numerous objects later discovered by archaeologists: in this brief paper I shall present the evi­dence which can be obtained from the currently known textual evidence regarding the craft of stoneworking. Lapidaries in the Ur III period economic texts (ca. 2000 B.C.) are designated exclu­sively by the cuneiform sign read zadim. The term zadim as a profession is attested from the earliest known under­standable texts, those from the site of Fara (ca. 2700 B.C.). Little useful information may be gained from these early texts since they are mainly ration lists, except for the probability that the term indicates an occu­pational or professional group, because the phrase ugula zadim is known, where ugula means ‘supervisor of .. (Deimel 1924, #71). A slightly later text provides some­what more useful information (Hackman 1958, #64): This text mentions zadim-za, literally ‘stoneworker in stone.’ Other texts from the same period indicate only that the zadim is classified with that group of work­men called gis-kin-ti ‘artisans.’ The best example of this is a list of rations of emmer wheat for the men who have the profes­sions of smith, carpenter, leather worker, lapidary, reed worker and rope maker, end­ing with the summary that they are all craftsmen (Hussey 1912, #5). Further establishment of the meaning of the term is provided by a text from the fol­lowing Sargonic period (i.e. 2330-2200 B.C.), (Nicolsky 1915, #87). In this text amounts of steatite, carnelian, and other types of stone are described as a delivery from a man with the title of zadim.

beryl, emerald, Colombia, Muzo, gems

There has been more activity in emerald mining in Colombia in the last few years than at any other time in the four centuries since the Spanish first discovered the deposits. This article combines a comprehensive review of the literature on the history and geology of Colombian emeralds with the author's own insighis into the current niarkeiing and mining of these stones. Ofparticular concern are the harsh nieihods now being used to extract the emeralds and the impact these methods will have on future production in Colombia. The past, however, has yielded many fabulous gems, the most famous of which are also described here and placed i n historical perspective.

gems, synthetic gems, synthetic corundum, synthetic beryl, YAG, GGG, CZ, synthetic spinel, syntheic opal, treated gems

The nineteen seventies were an exciting period, with many new developments in the field of synthetic gemstones. It was a difficult period for the gem expert as he struggled to keep up with a series of new synthetics, imitations, and treatments. For the user of gemstones these developments have provided a wide variety of new or improved, albeit “man-made,” products at costs well below the ever increasing inflationary prices and rarity of quality natural gemstones. The decade began with a bang in 1970 with the first successful growth of gemstone-size synthetic diamonds, as well as with the introduction of YAG as a diamond imitation; this rapidly superseded all the older materials. Soon thereafter, Pierre Gilson of France announced his synthetic opal in both white and black forms, as well as synthetic turquoise, later to be followed by his lapis lazuli and coral products. Commercial production of synthetic citrine and synthetic amethyst began in the USSR, while in the USA Linde discontinued its synthetic star ruby, star sapphire, and its synthetic emerald production (the last has been reactivated by another company). An authentic synthetic alexandrite and Slocum’s imitation opal have been additional new products. Towards the end of this decade, the most significant development was the meteoric rise of synthetic cubic zirconia, which almost overnight displaced essentially all the previous diamond imitations. Newly developed testing techniques are making the identification of this diamond look-alike a little easier. Another development has been the continuing rise of treatments used to “improve” natural gem materials; this includes irradiation as well as impregnations. In looking back over these rapid developments of the last ten years, one suspects that the next decade will not be quite so hectic; a period to digest and utilize more fully these advances may, perhaps, be anticipated.