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| THE ORIGIN OF GEMSTONES TISSA MUNASINGHE OF SRI LANKA AND C. B. DISSANAYAKE Department of Geology...Geology, University of Peradeniya,Peradeniya,Sri Lanka Sri Lanka is well known throughout the world for its...topaz, and zircon. Largescale gem mining is confined mainly to the Ratnapura and Elahera areas (Fig. 1)...1). In most local- ities gem minerals are recovered from residual, alluvial, and eluvial depositsthough...common (Dahanayake et al., 1980). The gem-bearing beds in the Ratnapura area are mostly alluvial in origin |
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| 2 TABLE OF CONTENTS FEATURE ARTICLES 62 Sri Lanka: The Gem Island Peter C. Zwnan The Identification...Illumination: A Controllable System of Lighting for Gem Microscopy John I. Koivula 8 7 Radioactive Irradiated...Greenland Aage Jensen and Ole V. Petersen Carving Gem-Quality Opal Theodore Grussing Two Notable Color-Change...REGULAR FEATURES Gem Trade Lab Notes Editorial Forum Gemological Abstracts Book Reviews Gem News , A B O...a n y fine gemstones found on the island o f Sri Lanka, the subject of Peter Zwaan's article i n this |
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| Tribute to Robert M. Shipley, Jr. The Chanthaburi-Trat Gem Field, Thailand Peter C. Keller 197 Gemstones with...Alexandrite Effect E. Giibelin and K. Schmetzer 204 Gem-Quality Grossular Garnets D. Vincent Manson and Carol...Crystal: The Van Pelt Collection John Sinkankcis 221 Gem-Quality Friedelite from the Kalahari Manganese Field...REGULAR FEATURES Gem Trade Lab Notes Editorial Forum Gemological Abstracts Book Reviews Gem News Index to...Liddicoat, Jr. Associate Editor Peter C. Keller Editor, Gem Trade Lab Notes Chuck Fryer Editor, Gemological Abstracts |
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| inclusions or these cannot be seen because the host gem is too opaque. The brownish opal termed hyalite,...KennethScarratt, Kenneth Scarratt, F.G.A. F.G.A. The Gem Gem Testing Testing Laboratory Laboratory of of Great...Laboratory's name that has changed, firstly from 'The Gem Testing Laboratory of the London Chamber of of Commerce...Commerce and Industry' and then to 'The British Gem Testing Laboratory of the London Chamber ofCommerce...The The Laboratory Laboratory is now known as 'The Gem Testing Laboratory of of Great Britain'.. Britain' |
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| Colombian Emeralds Ron Ringsmd The Elahera Gem Field in Central Sri Lanka Mahinda Gunawardene and Mahinda S....Nassau REGULAR FEATURES Editorial Forum Gem Trade Lab Notes Gem News Gemological Abstracts Book Reviews...LaFayette, Indiana Sallie Morton San lose, CA Editor, Gem Trade Lab Notes C . W. Fryer Editor, Gemological...Jeffrey M. Burbank Contributing Editor and Editor, Gem News John I. Koivula Production Assistant Patricia...COLOMBIAN EMERALDS By Ron Ringsrud The Muzo emerald district, i n Boyacd, Colombia, contains several mines |
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| invite you to be our guest at Hong Kong Jewellery & Gem Fair September 16th-20th 2019 AWE - Booth 8E03 German...Spinel Pink and Red Gem Spinels in Marble and Placers Spinel from Tajikistan – The Gem That Made Famous...Spinels of Mogok – A Brief Overview Spinels from Sri Lanka 54 The Spinels of Mahenge, Tanzania In Search...Responsibility 94 Book Review Discovering the Gems of Sri Lanka 98 100 108 113 Members 14 Saurabh Bansal Damien...Shirley Xue Li Zhang, Hong Kong E. Gamini Zoysa, Sri Lanka Advisors Jean Claude Michelou, Colombia Ruben |
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| 5 JANUARY 1977 KORNERUPINE CAT'S-EYES FROM SRI LANKA (CEYLON) By H. J. KOREVAAR, F.G.A., Ter Aar, Netherlands...authors (Korevaar), visiting Sri Lanka, bought a parcel of 125 cat's-eyes from a gem dealer in Galle. Although...Weligama gem gravels in the Matara district. Back in Holland, Korevaar contacted the Dutch Gem Laboratory...trip to Sri Lanka in February 1976, the authors noticed a lot of these stones in the Ratnapura Gem Museum...stones offered for sale by people in the street in Ratnapura. It is very likely, therefore, that in the near |
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| Edelseifen um Ratnapura . . . . . . . . . . 22 Lageskizze der Edelsteinfelder in der Provinz Sabaragamuwa Ceylons...Polonnaruwa • Kandy Nuwara Eliya Adam's Peak Ratnapura • .Pelmadulla • Rakwana Malara Karte von Ceylon...altorientalisches Dichterwort die paradiesische Insel Lanka an der Siidspitze Indiens. Es hat bis heute seine...von Edelsteinen wie gerade Ceylon.Bereits in den Lanka-Sagen finden sich manche Hinweise auf Ceylons Edelsteinreichtum...ausser Gewiirzen auch Perlen und edle Steine aus Lanka, wie Ceylon im Altertum hiess, exportiert wiirden |
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| the authors 4 Iolite (cordierite) 55 Is it a gem? 5 Andalusite, Fibrolite (sillimanite) Finding...Further reading and credits 73 Tanzanite 54 Gem deposits of the world 74 Taaffeite 54 Index ...qualities of beauty, rarity and about the individual gem species. The main durability, which are determined...are described, together with identifying gems. Gem mineral formation is notes on items of particular...outreach and (GAGTL) and the British examiner for the gem testing services. Prior to this post die was European |
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| E. Post, Geologist, Curator-in-Charge, National Gem and Mineral Collection, National Museum of Natural...at www.dk.com CONTENTS INTRODUCTION What is a Gem? 8 How Gems Form 10 Crystals 12 Classifying...Cutting Gems 28 Polishing and Engraving Gems 30 Gem Enhancement 32 Synthetic Gems 34 History and... 214 Index 218 Acknowledgments 223 HOW THE GEM PROFILES WORK main section ; profile information...viene INTRODUCTION ‘ag yet Gay x 2 WHAT IS A GEM? Gems are generally defined as precious or semiprecious |
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| carats from Burma. gemstones. Tanzania. Rare Sri Lankan orange sapphire of 57.26 carats. Emerald...illustrated. The section ends with a brief account of gem cutting. The most popular gemstones are described...final section of the book is concerned with how gem minerals form, where they are found and how they...are identified, and a selected index to the main gem species, technical terms and important topics such...Geological Museum in London. The collection consists of gem minerals in both a natural state and cut as exquisite |
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| Dimensions in the captions refer to the entire gem or mineral; however, in some cases only a portion...A CHANGING PLANET 11 Vanadinite, San Carlos district, Chihuahua, Mexico * 8 x 4 x 2 cm Mineral Species...can be as valuable as the richly colored stones. Gem cutters bring out the inner beauty of gems by creating...trick with light. Facets allow light to enter the gem; once inside, the light bounces off its other angled...Africa and Canada « 2.00 ct and 3.06 ct leaves the gem, similar to what happens when you pass light through |
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| E YE WI TNES S HA N D B O O KS GEM STONES The visual guide to more than 130 gemstone varieties...org/details/gemstoneseyewitnOOcall EYEWITNESS HANDBOOKS GEM STONES E YE WI TNESS HANDBOOKS GEMSTONES Cally...varieties are found and fashions change. Over 130 gem species, including some exceptionally rare stones...why the species entries in this its book show the gem rough, natural state, perhaps embedded in still...they can be appreciated by anyone, from the amateur gem-spotter to the enthusiast who enjoys their beauty |
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| Ian Ballour) Contents INTRODUCTION GEM IDENTIFIER Main gem groups Other gemstones Natural glasses...have tried to recognize these fakes. Synthetic gem- and optical properties by which they may be identified...on the scale grains that make them the toughest gem¬ but was in turn scratched by those beneath stones...be un¬ (9) and talc (1). For use in jewellery, gem¬ even, hackly (jagged) or conchoidal (shell - stones...hardness less than 7 are therefore likely common, gem-quality material may be to become scratched with |
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| Properties of crystals Gem crystals 18 19 19 20 20 21 22 32 33 3 3.1 3.2 3.3 Gem testing Hardness Gemstones...56 4 4.1 4.2 4.3 4.4 4.5 Recent developments in gem testing 59 59 60 61 64 65 Thermal conductivity...understandably and rightly, with the science of gem testing and have covered that area very well. Details...entirely new gem mineral species have been found in the last few years; tanzanite, appearing on the gem market...with no gem potential whatever. It is not likely that many entirely new mineral species with gem application |
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| BUTTERWORTHS GEM BOOKS GARNET JOHN DROUSE ♦ BUTTERWORTHS ◊ Butterworths Gem Books Edited by Peter...P. J. Darragh Topaz D. B. Hoover Butterworths Gem Books Garnet John D. Rouse Butterworths London...PublicationData Rouse.John D. Gamet.-(Butterworths gem books) 1. Gamet I. Title 553.8'7 QE391.G37 ISBN 0-408-01534-9...Rouse. John D. (John David) Gamet. (Butterworths gem books) Includes bibliographies and index. 1. Gamet...garnets from the perspective of a cutter, dealer and gem enthusiast. The main purpose of this work is not |
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| North-West Branch: S. Hill, F.G.A. South Yurkshire & District Branch: J. L Reynolds, F.G.A. Examiners: E. A...Phil., F.G.A.†and V.K. Din, C.Chem., M.R.S.C.†*Gem Testing Laboratory of Great Britain, 27 Greville...with lavas and there is only one major volcanic province - that of Thailand and Kampuchea (Cambodia) -...the Laboratory - 8 Kenneth Scarratt, F.G.A. The Gem Testing Laboratory of Great Britain, 27 Greville...rare gemstone but also in the presentation of any gem material, it is a pleasure to see a diamond fashioned |
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| © Tere crree! THE CLEVER GEM BUYER Sclaolalemcveliareln GAVIN LINSELL “She is more precious than...the main reason invariably is that a particular gem means something special to us: they represent a story...perceptions. Now in its second edition, The Clever Gem Buyer brings the reader not only the ‘gemmological’...in an absorbing and entertaining way, The Clever Gem Buyer’s second edition includes even more gemstone...mountain of gemstone rings’ in Thailand's Chanthaburi Province, an international centre for coloured gemstones |
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| EDITION AREM, PH.D., FG.A. gem gemologists, 1977, jewelers, and gem collectors, dealers have relied...INTRODUCTION What / Gem? a / Scope of This Book / Is The Nature Gems of GEM SECTION 1 2 GEMSTONES...Rock Classification Gem Scarcity Intrusive Crystal 6 Growth Synthetic Gem 9 / Gemstones SOURCES...dealers are aware of the growing value of exotic gem species; the list of known taaffeites has thus grown...greater monetary reward than are the tists who gem scien- build detection equipment. Inevitably, a |
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| r· Butterworths Gem Books Edited by Peter G. Read Amber Helen Fraquet Beryl John Sinkankas and Peter... Huddlestone Topaz D. B. Hoover Butterworths Gem Books Corundum Richard W. Hughes Executive Vice...Corundum/Richard W. Hughes. p. cm.-{Butterworths gem books) Bibliography: p. Includes index ISB!'i 0-7506-1006-9:... Major sources: Burma, Thailand, Cambodia, Sri Lanka, India, Australia, Kenya, Tanzania, Montana and...we have books on gem deposits, the lapidary arts, carved gems, gem treatments, gem identification, history |
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| 1 2 The Geological Sources of Gems Crystalline Gem Materials 3 40 Part II 3 4 5 6 7 8 9 10 11 12 13...The Biological Gem Materials The Fashioning of Gemstones Value-Enhanced Gemstones and Gem Materials 292...library for virtually all sources. Derivations of gem and mineral names are not given; they can be found...not now considered valid or current. While many gem collectors collect mineral specimens too, the text...text for the 1994 edition. In this new edition, the gem testing section has been omitted; this information |
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| provides a comprehensive examination of gems and gem materials including discussion of their properties...and popularity in different cultures. The Museum's gem collection, itself the stuff of legends, is described...factors important in determining the quality of each gem and spells out the possible confusions in gemstone...TO THOSE WHO HAVE HELPED CREATE THE MINERAL AND GEM COLLECTIONS. Those whose donations are featured...Tourmaline PAGE 88 18 Zircon& What1a Rridot Gem? PAGE PAGE 22 Corundum Diamond PAGE PAGE 44 |
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| Sapphires from Sri Lanka Kcirl Scl~metzerand Olaf Medenbach REGULAR FEATURES 112 120 124 131 Gem Trade Lab...Lab Notes Gem News Gemological Abstracts Book Reviews ABOUT THE COVER: The extraordinary play-of-color...Diffraction, one of the less common causes of color in gem materials, is described in this issue in the third...extensive listing of the known origins o f color in gem materials. The opal, from the Ditto 3 Harold &> Collection...pit. Virtually all o f the diamonds recovered are gem quality, although most are relatively small, averaging |
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| Gemesis CVD synthetic diamond New sapphires from Sri Lanka Cultured pearls from Micronesia VOLUME 48 NO...reputation? It’s the most reliable, authentic, dependable gem institute in the world. People know that, especially...Sapphires from Thammannawa, Kataragama Area, Sri Lanka Pannipitiye G. R. Dharmaratne, H. M. Ranjith Premasiri...sapphires, the object of a recent gem rush in southeastern Sri Lanka, possess good transparency and a...research efforts have led to dramatic progress in gem-quality CVD synthesis and post-growth treatment. |
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| chrysoberyl, demantoid, diamond, enstatite, hessonite, hiddenite, kornerupine, kunzite, kyanite, peridote...gemstones survive it all. On the other way round, gem minerals can also be used as pathfinder minerals...linked to these gemstones in magmatic and metamorphic gem deposits. All placer types known to be relevant for...corundum. Minerals 2018, 8, 470 3 of 43 Table 1. Gem minerals found in placer deposits, their physical...their source rocks and the sedimentary traps. The gem placer deposits are subdivided according to the “Chessboard |
Gem gravels, Ratnapura, Ratnapura District, Sabaragamuwa Province, Sri Lanka