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.

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.

jade, jadeite, fei cui, Central America, Guatemala, gems, turquoise

Jade was a mineral of peculiar significance for the peoples of pre-Columbian Mesoamerica and especially for the Maya, whose civilization flourished in the Yucatán Peninsula through most of the first millennium A.D., to whom it was “the precious stone of grace, the first infinite grace,” its green color making it an allegorical metaphor of young corn, of flowing water, of life itself (Thompson 1950). At the time of Conquest, jade was also important to the Aztecs, who distinguished several types (Foshag 1955): chalchihuitl, which may be translated “herb-green jewel-stone,” referring to ordinary grades of jade; quetzalitztli, from the iridescent green tail-feathers of the quetzal, a bird of the Maya highlands, probably denoting the finest translucent emerald-green jade; tlilayotic, which may refer to the dark green chloromelanite or to omphacite; and iztaccichalchihuitl, white chalchihuitl, which is most likely to be albitic jadeite. The first European contact with the material seems to have been in the sixteenth century, when it was noted as being used for axes in Amazonia, and the word itself is of Spanish etymology, from piedra de ijada—“colic stone”—because of its reputed medicinal properties among some groups of Indians in South America. The term “nephrite” for one mineralogical variety of jade was coined from this by Latinization. After the exhaustion of the current stock of precious jades in Mesoamerica following the conquest, the stone ceased to have any importance for the Spaniards; and the jade best known to later European society was the nephrite from Sinkiang worked in China from Han times onwards and, latterly, Burmese jadeite. Mesoamerican jade sources have remained unworked and mainly unknown to the present day, although the rising value of the raw material is leading to renewed exploitation.

gems, corundum, synthetic corundum.7, synthetic quartz, synthetic opal, synthetic emerald, synthetic diamond

The father of crystal fabrication technology is A. Verneuil with his flame-fusion growth method 1902. His principles of nucleation and growth control are adapted in most later growth methods from melt. The Czochralski method was essentially developed by Teal, Little and Dash. The multidisciplinary nature of crystal growth and epitaxy technology and the complex multiparameter processes, and also the scaling problem, have impeded the scientific development of this important area. Only recently it was possible to solve the striation problem and to understand the control of epitaxial growth modes for achieving structurally perfect layers of GaAs and high-Tc superconductors with atomically flat surfaces. The formation of crystal growth and epitaxy engineers and scientists as well as centers of excellence are necessary in order to develop crystal and epilayer fabrication technologies required for development of highest-efficiency white light-emitting diodes and photovoltaic solar cells for energy-saving lighting and as alternative source of energy. Also laser-fusion energy and other high technologies have to wait for progress in crystal growth technology.

corundum, history.1, India.12, gems, Indian lapidary

From ancient times, India has been renowned as a land of jewels and the principal source of precious stones. This paper seeks to explore, through ancient Indian sources, the extent of knowledge Indians possessed about precious stones in antiquity—the types of gems mentioned in these texts, and how such knowledge traveled beyond India’s borders to other parts of the ancient world, ultimately reaching the classical authors who have preserved it into modern times. A preliminary question arises: what qualifies as a “precious stone” in these contexts? While there is no universally fixed definition, stones have traditionally been classified based on qualities such as color, brilliance, hardness, durability, and rarity—though these criteria have evolved over time. A select group of more valuable minerals came to be known simply as precious stones (gemmae), while those similar in nature but of lesser value were labeled semi-precious (lapides pretiosi). Diamonds, emeralds, sapphires, and rubies typically fall into the precious category, while opals, topaz, hyacinth, and others—known in both Latin and Sanskrit—are usually considered semi-precious.