corundum, synthetic corundum.7, color.4, gems

A practical introduction to scientific gem identification written primarily for jewellers, dealers, and pawnbrokers without formal gemmological training. Drawing on his experience at the Precious Stone Laboratory of the London Chamber of Commerce, Anderson explains how simple instruments and observations can supplement traditional visual identification and distinguish natural gemstones from synthetics and imitations. The opening chapters describe the principles and practical use of the refractometer, double refraction, colour filters, dichroscope, specific gravity measurements, microscope, and spectroscope. Particular attention is devoted to detecting synthetic corundum through curved growth lines, gas bubbles, colour zoning, and the absence of characteristic natural inclusions, with additional discussions of synthetic spinel, synthetic emerald, glass imitations, and composite stones. Subsequent chapters provide systematic identification procedures for diamond, ruby, sapphire, emerald, opal, alexandrite, zircon, aquamarine, topaz, quartz, garnet, tourmaline, peridot, spinel, and numerous other gem materials, including translucent and opaque stones. Organic materials such as amber, tortoiseshell, coral, jet, and pearls are also examined, with methods for distinguishing natural, cultured, and imitation pearls. Throughout, Anderson emphasizes inexpensive, nondestructive tests, practical experience, and the use of several independent observations to establish reliable identifications. Numerous photomicrographs, diagrams, comparative tables, and an appendix of gem properties complement the text. Published during the Second World War, the book provides an important historical record of gemmological testing techniques and instrumentation available to the jewellery trade in the early 1940s, particularly the developing importance of microscopy, absorption spectroscopy, and the Chelsea colour filter.

gems, beryl, emerald, India, Rajasthan

During World War II, an intensive search was conducted in Rajputana for high-quality beryl and mica. Among those actively involved was Sir Bhagchand Soni, a prominent banker and financier in Ajmer, who financed prospecting parties across a considerable area in north-western Mewar. Although both mica and beryl were found, the deposits ultimately proved commercially disappointing. However, prospectors sent some small green beryl crystals to Sir Bhagchand, who forwarded them to the Mica Production Section of the Geological Survey of India in Ajmer for analysis. While the report could have dismissed the crystals as ordinary green beryl of little value unless found in large quantities, it happened that the Officer-in-Charge had recently seen boxes of crude Russian emeralds unpacked by a major lapidary firm in Jaipur. Recognizing that the Mewar crystals matched the quality of the Russian specimens, he identified them as beryl of the emerald variety and recommended that Sir Bhagchand secure a mining lease for the area. This is the first documented occurrence of emerald in India and thus an important paper.

gems, early science, early optics, Arabic mineralogy, Arabic science, eyeglasses, sunglasses, beryl, aquamarine, Ptolemy, early lapidaries

In classical literature, mention is sometimes made of the magnifying power of transparent media, but it is improbable that magnifying glasses were known in Europe before the 13th century. Ptolemy, who lived at Alexandria around A.D. 150, gives some details concerning lenses and discusses the course of rays of light passing from one medium into another, but as the last part of his famous treatise on optics is lost, one cannot tell how extensive his knowledge was. It was the Arab Alhazen (circa A.D. 1000) who wrote on magnifying glasses. He describes how objects, when seen through a segment of a sphere with an index of refraction greater than that of the surrounding air (“grossius aere”), appear larger than they are in reality. This optical effect of lenses is not described in European literature before the 13th century. It is generally held that Roger Bacon (c. 1214–1294) was the first European scholar to mention the practical utility of lenses. In his Opus maius (written 1266–1267), he describes how to magnify writing by placing a segment of a glass sphere on the text with its plane side down. But, as shown elsewhere, there was another Englishman, Robert Grosseteste (1175?–1253), Bishop of Lincoln, who anticipated Bacon. In his treatise De iride seu de iride et speculo there is a passage which can be translated thus: “…it will be perfectly clear… how far and how large and in what shape a body, of which the distance, size, and place are known, will appear to the eye, when there is a diaphanous body, of which the distance, size, and place are also known; and it is clear in what manner transparent bodies must be moulded, so that they may receive the visual rays, emanating from the eye, under an angle as wide as they wish it, and how they may collect the rays on the visible objects, whether those objects are big or small, far or near; and so they may see each visible object wherever and in any size they wish; and they may operate, so that very long objects appear to be short and, in contrast, that very small and far objects are clearly visible.” As far as I know, Robert Grosseteste was the first scholar in Western Europe who wrote on optics, and so he deserves well of science. There was a third Englishman who had great merits in connection with optics—John Peckham (1228–1294), Archbishop of Canterbury, renowned for Perspectiva communis, a book which appeared in subsequent centuries in several printed editions.

corundum, quality.10, India.12, Tajikistan.12, spinel, gems, Indian lapidary

Aziz’s The Imperial Treasury of the Indian Mughuls examines the extraordinary wealth accumulated by the Mughal emperors and the organisation and contents of the imperial treasury. Drawing on contemporary chronicles, travellers’ accounts and other historical sources, the work describes the vast quantities of gold, silver, jewels and precious stones held by the Mughal court, together with jewelled ornaments, ceremonial objects and other valuables. Particular attention is given to diamonds, rubies, emeralds, pearls and other gems, including celebrated stones associated with the emperors and the ways in which such treasures were acquired, valued, stored and displayed. The study also places the treasury within the wider setting of Mughal court life, where gemstones and jewellery served not merely as stores of wealth but as important symbols of sovereignty, rank and imperial magnificence.

gems, beryl, emerald, Colombia

Klein recounts his travels and prospecting adventures in Latin America in search of gemstones, with particular emphasis on the emerald deposits of Colombia. Written as a personal travel and exploration narrative rather than a technical mineralogical treatise, the book describes the difficulties of reaching remote mining districts, local mining conditions, dealings with miners and traders, and the practical realities of searching for emeralds in tropical terrain. Of particular importance is his account of the Chivor emerald region and his discovery of the celebrated approximately 650-carat emerald crystal that he named “Patricius.” The volume combines firsthand observations on emerald mining and the gem trade with descriptions of landscape, travel, and encounters in Latin America, and is illustrated with numerous photographic plates. It is therefore valuable both as a contemporary account of Colombian emerald mining and as a record of the activities of an Idar-Oberstein gem cutter and prospector working in South America before the Second World War.

gems, corundum, ruby, sapphire, topaz, beryl, emerald

Sinkankas: Beautiful watercolor drawings by Lang, a professional artist, showing cut and/or rough gemstones, and forming the main attraction of this booklet. The text by Schnack is brief and stresses attraction & lore of gems. Rev. B.W. Anderson, The Gemm., 8, 94, 1937, 164–5.

gems, beryl, emerald, Colombia, Muzo, geology, trapiche beryl, emerald

Scheibe presents the results of his 1916 geological investigation of the Muzo emerald mine, describing the regional geology, structure of the deposit, emerald-bearing veins, associated minerals, and contemporary mining operations. The emerald deposits occur in black Cretaceous shales traversed by mineralized veins and fractures containing calcite, dolomite, pyrite, albite, quartz, and other minerals. Scheibe examines the relationships between these veins and the surrounding rocks and discusses the processes responsible for emerald formation, including alteration and mineralization of the country rock. Considerable attention is given to the occurrence and distribution of emerald within the workings, the characteristics of productive and barren veins, and the practical implications of the geology for exploration and mining. The volume also incorporates F. Bernauer’s study of the unusual multiple or mimetic emerald crystals from Muzo and their optical anomalies, as well as Scheibe’s report on emerald occurrences at Nemocón, extending the discussion beyond Muzo to the relationship between emerald mineralization and Colombia’s salt-bearing formations. Together these studies constitute an important early scientific investigation of Colombian emerald geology, mineralogy, crystallography, and genesis.

beryl, emerald, Colombia, Chivor, gems

gems, beryl, emerald, Colombia, Chivor

The Chivor emerald field is situated on the eastern slope of the Andes in the Department of Boyacá, at an elevation of about 8000 ft. above sea level. It overlooks the Llanos (plains) of the Orinoco and is watered by many streams flowing into the Rio Meta, the Orinoco's largest tributary. The Rio Meta is navigable from the Orinoco to a point within about 50 miles of the Chivor district and may eventually prove to be the reasonable outlet for the future development of this part of the country. The topography of the district is extremely rugged and mountainous (Fig. 1), the difference in elevation between two points on a mining claim 1 km. square being sometimes as much as 4000 ft. The ground is covered with dense forest growth and the available timber is suitable and sufficient for mining purposes, but it is becoming gradually depleted by Indian clearings as the country around the mines becomes settled. The many streams combined with the rough topography give good possi-bilities for hydroelectric power. The center of population nearest to Chivor is Bogotá, the capital of the republic and a city of some 300,000 inhabitants; the distance is two and one-half days' travel. The first stage of the journey from Bogota, is accomplished by rail to Chocont·, some 4 hr. travel. From Chocont· the journey is made in the saddle, one night being spent in Guateque. The latter is a small town and the nearest post office to the mines, being some 10 hr. ride distant. The roads are mere bridle paths, in parts hazardous and almost impassable in the wet season. All supplies brought to the mines, other than those produced locally, are carried by pack mule; mule freight from Chocontá costs 3 centavos1 per pound. The climate of the Chivor district is healthful and bracing. The wet season begins in March and concludes in November, the remaining months being dry. The annual precipitation is about 150 in. The temperature throughout the year is nearly constant, varying from about 45∞ F. to about 65∞ F. shade temperature. The rains are cold and unpleasant, and for the greater part of each day in the wet season the country is shrouded in dense mist. A fire can with comfort be kept burning in a living room all the year round.

gems, Arabic lore, history, Arabic mineralogy,

Storey’s Persian Literature: A Bio-bibliographical Survey is a monumental reference work devoted to Persian writings and their authors, arranged principally by subject and providing biographical information, titles and descriptions of works, manuscript locations, editions, translations, and secondary literature. Rather than a history of Persian literature in narrative form, it functions as an extensive bibliographical guide to the surviving Persian literary tradition, including history, biography, geography, travel, mathematics, astronomy, medicine, the natural sciences, religion, poetry, and related subjects. Of particular relevance to the history of gemology are its references to Persian scientific and mineralogical literature, including works dealing with precious stones, minerals, metals, and associated technical traditions, and its documentation of manuscripts and editions through which these texts are known. The survey is especially valuable for identifying variant titles, authorship and chronology, locating manuscripts in European and Asian collections, and tracing earlier scholarship. Originally begun by Charles Ambrose Storey and subsequently continued and substantially expanded by François de Blois, it remains an important bibliographical tool for the study of Persian manuscripts and the transmission of scientific and technical literature. The entire work is available online at Storey Online.