DOCSLIB.ORG

Winter 2006 Gems & Gemology

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Winter 2006 Gems & Gemology VOLUME XLII WINTER 2006 Impact of Graining on Diamond Clarity Grading . “Chocolate Pearls”. Leopard Opal . Rainbow Andradite from Japan THE QUARTERLY JOURNAL OF THE GEMOLOGICAL INSTITUTE OF AMERICA ® Winter 2006 VOLUME 42, NO. 4 EDITORIAL _____________ 205 Remembering G. Robert Crowningshield Alice S. Keller FEATURE ARTICLES _____________ 206 The Impact of Internal Whitish and Reflective Graining on the Clarity Grading of D-to-Z Color Diamonds at the GIA Laboratory Carat Points John M. King, Thomas M. Moses, and Wuyi Wang A study of two important types of graining and how GIA determines their impact on a diamond’s clarity grade. pg. 216 222 Identification of “Chocolate Pearls” Treated by Ballerina Pearl Co. Wuyi Wang, Kenneth Scarratt, Akira Hyatt, Andy Hsi-Tien Shen, and Matthew Hall Examines the “chocolate” color treatment process for cultured pearls and techniques for identifying these products. 236 Leopard Opal: Play-of-Color Opal in Vesicular Basalt from Zimapán, Hidalgo State, Mexico Robert Raymond Coenraads and Alfonso Rosas Zenil A look at the origin and properties of this colorful ornamental stone, which is known from only one source. 248 The Cause of Iridescence in Rainbow Andradite from Nara, Japan Thomas Hainschwang and Franck Notari Characterizes this iridescent garnet from Japan and explains the cause of pg. 223 its unusual color phenomenon. REGULAR FEATURES _____________________ 260 Lab Notes Lizards in imitation amber • Large demantoid of exceptional color • A large Fancy white diamond with whitish banding • Prolonged change of color in a pink diamond • Strand of natural nacreous and non-nacreous pearls • Poudretteite • Unusual gem pyroxmangite 268 Gem News International Diamond trading in Sierra Leone • Jewelry repair damages a diamond • Green pg. 260 augelite from Peru • Bicolored beryl from Namibia • Diopside from Afghanistan • California jadeite with copper inclusions • Labradorite from Mexico • Gem news from Mogok, Myanmar • Moonstone from Madagascar • Phenomenal fire opal • “Sunset” quartz from Brazil • Swedish Blue (slag) and Swedish Iron Ore • Tourmaline mining at Nandihizana, Madagascar • Green uvite from Afghanistan • Synthetic corundum “gem rough” in Tanzania • Small treated synthetic pink diamonds • “Chocolate” Tahitian cultured pearls • Treated violetish blue quartz from Brazil • Circular inclusions in a diffusion-treated sapphire • Diffusion-treated synthetic sapphire with unusual fluorescence 293 2006 Challenge Winners 294 Book Reviews 297 Gemological Abstracts 309 2006 Index pg. 269 EDITORIAL Editor-in-Chief Editor Editors, Lab Notes STAFF Alice S. Keller Brendan M. Laurs Thomas M. Moses [email protected] The Robert Mouawad Campus Shane F. McClure 5345 Armada Drive Managing Editor Carlsbad, CA 92008 Editor, Gem News International Thomas W. Overton (760) 603-4503 Brendan M. Laurs [email protected] [email protected] Technical Editor Editors, Book Reviews Associate Editor Sally Magaña Susan B. Johnson Stuart Overlin [email protected] Jana E. Miyahira-Smith [email protected] Stuart Overlin Consulting Editor Circulation Coordinator Carol M. Stockton Debbie Ortiz Editors, Gemological Abstracts Contributing Editor (760) 603-4000, ext. 7142 Brendan M. Laurs James E. Shigley [email protected] Thomas W. Overton PRODUCTION Art Director Production Assistant Website: STAFF Karen Myers Allison DeLong www.gia.edu EDITORIAL Shigeru Akamatsu Alan Jobbins George Rossman REVIEW BOARD Tokyo, Japan Caterham, United Kingdom Pasadena, California Alan T. Collins Mary L. Johnson Kenneth Scarratt London, United Kingdom San Diego, California Bangkok, Thailand John Emmett Anthony R. Kampf James E. Shigley Brush Prairie, Washington Los Angeles, California Carlsbad, California Emmanuel Fritsch Robert E. Kane Christopher P. Smith Nantes, France Helena, Montana New York, New York Henry A. Hänni Lore Kiefert Christopher M. Welbourn Basel, Switzerland New York, New York Reading, United Kingdom A. J. A. (Bram) Janse Thomas M. Moses Perth, Australia New York, New York SUBSCRIPTIONS Subscriptions to addresses in the U.S. are priced as follows: $74.95 for one year (4 issues), $194.95 for three years (12 issues). Subscriptions sent elsewhere are $85.00 for one year, $225.00 for three years. Canadian subscribers should add GST. Special rates are available for GIA alumni and current GIA students. One year: $64.95 to addresses in the U.S., $75.00 else- where; three years: $179.95 to addresses in the U.S., $210.00 elsewhere. Please have your student or Alumni number ready when ordering. Go to www.gia.edu or contact the Circulation Coordinator. Single copies of this issue may be purchased for $19.00 in the U.S., $22.00 elsewhere. Discounts are given for bulk orders of 10 or more of any one issue. A limited number of back issues are also available for purchase. Please address all inquiries regarding subscriptions and single copy or back issue purchases to the Circulation Coordinator (see above) or visit www.gia.edu. To obtain a Japanese translation of Gems & Gemology, contact GIA Japan, Okachimachi Cy Bldg., 5-15-14 Ueno, Taitoku, Tokyo 110, Japan. Our Canadian goods and service registration number is 126142892RT. MANUSCRIPT Gems & Gemology welcomes the submission of articles on all aspects of the field. Please see the Guidelines for Authors on our SUBMISSIONS Website, or contact the Managing Editor. Letters on articles published in Gems & Gemology are also welcome. Abstracting is permitted with credit to the source. Libraries are permitted to photocopy beyond the limits of U.S. copyright law COPYRIGHT for private use of patrons. Instructors are permitted to photocopy isolated articles for noncommercial classroom use without fee. AND REPRINT Copying of the photographs by any means other than traditional photocopying techniques (Xerox, etc.) is prohibited without the express permission of the photographer (where listed) or author of the article in which the photo appears (where no photographer PERMISSIONS is listed). For other copying, reprint, or republication permission, please contact the Managing Editor. Gems & Gemology is published quarterly by the Gemological Institute of America, a nonprofit educational organization for the gem and jewelry industry, The Robert Mouawad Campus, 5345 Armada Drive, Carlsbad, CA 92008. Postmaster: Return undeliverable copies of Gems & Gemology to The Robert Mouawad Campus, 5345 Armada Drive, Carlsbad, CA 92008. Any opinions expressed in signed articles are understood to be the opinions of the authors and not of the publisher. ABOUT Treated-color “chocolate” cultured pearls created from Tahitian cultured pearls have become a popular segment of the pearl THE COVER market in recent years. The article by Dr. Wuyi Wang and co-authors on pp. 222–235 of this issue examines a selection of “chocolate pearls” treated by Ballerina Pearl Co. in order to determine the basic process used and means of identifying these treated pearls. The “chocolate pearls” in the necklace range from ~12.0 to 13.7 mm; those in the earrings are 12.1 mm (left) and 12.3 mm (right). Jewelry courtesy of Emiko Pearls International; photo by Robert Weldon. Color separations for Gems & Gemology are by Pacific PreMedia, Carlsbad, California. Printing is by Allen Press, Lawrence, Kansas. © 2006 Gemological Institute of America All rights reserved. ISSN 0016-626X emology lost one of its original pioneers with the pass- G&G article, from the ing of G. Robert Crowningshield on November 8 at the Summer 1989 issue, age of 87. During a career that spanned six decades, his was on the first formal wide-reaching achievements as a researcher, author, and grading of the famed educator helped shape modern gemology. Hope diamond. Born in Colorado Springs, Colorado, Bob Crowningshield graduat- Many other discover- ed from San Diego State College (now San Diego State University) ies were set forth in with a degree in natural science. As an officer in the U.S. Navy Crowningshield’s from 1942 to 1946, he read books on gems to pass the long hours long-running G&G at sea and even arranged an unscheduled stop in Colombo, the column, which con- capital of Ceylon (now Sri Lanka) and a bustling trade center for tained brief notes gems. As fate would have it, the owner of the first jewelry store he from the New York visited had a son who had graduated from GIA’s resident program lab (and eventually in Los Angeles in 1939. When the young man told Crowningshield became the journal’s present-day Lab Notes section). Between of a school dedicated to the science of gems, his destiny became 1957 and 1999, he turned out more than 1,000 observations of clear, and he enrolled at GIA once his tour of duty was over. interesting and unusual gems. His 1970 note on “milky” graining in diamonds was the first articulation of what has become an After graduating from the Institute in 1947, Crowningshield stayed important feature in the clarity grading of diamonds, as described on campus in Los Angeles as an instructor. Two years later, he was in the lead article in this issue. sent to New York to help start up GIA’s East Coast office, where he worked for more than four decades, rising to the position of vice His scientific achievements alone would have earned Bob president. Crowningshield a place in gemological history, but they don’t tell the whole story. His reputation for accuracy and integrity played a Crowningshield championed the spectroscope as a tool for gemo- key role in establishing GIA’s diamond grading reports as an indus- logical research. Pencil in hand, he sketched absorption spectra for try standard. Crowningshield was also a respected educator who every stone he examined. His collection of hand-drawn illustra- taught scores of jewelers across the United States and presented at tions, first published in Richard T. Liddicoat’s 1962 edition of the all but two American Gem Society (AGS) Conclaves from 1951 to Handbook of Gem Identification, demonstrated the value of the 1993. (A complete review of his career can be found in Thomas spectroscope to gemologists.
Load more

Recommended publications
  • Painite, Cazrblllro,Rl: Its Crystal Structure and Relation To
    American Mineralogist, Volume 61, pages 88-94, 1976 Painite, CaZrBlLlrO,rl: Its crystalstructure and relationto jeremejevite,Bu[[rAl6(OH)sO1r], and fluoborite, Br[Mgr(F, OH)rOr] Plur- BRre,uMooRE r.No TnreHnnu AnerI Department of the Geophysical Sciences, The Uniuersity of Chicago Chicago, Illinois 60637 Abstract Painite-CazrB[Al,O,s], hexagonalP6s, a :8.715(2), c : 8.472(2)A,Z : 2-possessesa rigid and dense [AlrO,r]'- octahedralframework, topologically identical to those found in jeremejevite, B'[IBAI6(OH)aO,,] and fluoborite, B,[Mg,(F,OH),O,]. R : 0.071 for l6l8 independent reflections. The octahedralframework is linked to [BOr]3 trianglesand [ZrOu]8-trigonal prismsatlf z and a largepipe at 0 0 z is cloggedwith compressed[CaO"]'0- octahedra. Average interatomic distancesareCa-O=2.398,2r-O:2.126,8-O:1.380,A1(l)-O: l.9l5,Al(2)-O: 1.918, and Al(3)-O : l.9l4A. The octahedral framework in painite, resistantto attack by acids and bases,suggests a highly refractoryphase and the possibilityof other equally resistantcompounds, hypothetical examplesbeing NaNbs+B[Alrors] and llUutB[Al"O,"]. ln the latter, thepipewould be lree from obstructions. Introduction Three-dimensionalsingle-crystal X-ray diffraction intensitiesabout the a2-rotation axis were collected Painite is a curious mineral species,first reported on a PnILnrn semi-automateddiffractometer with by Claringbull, Hey and Payne(1957) from the ruby graphite monochromatized MoKa, (tr : 0.70926A) minesof Mogok, Burma. It was found as a garnet-red radiation. With 2d-^* : 69.5", data were gathered 1.7 gram singlehexagonal crystal of hardness8. They through the k -- 0- to ll-levels.
    [Show full text]
  • New Data on Painite
    MINERALOGICAL MAGAZINE, JUNE 1986, VOL. 50, PP. 267 70 New data on painite JAMES E. SHIGLEY Research Department, Gemological Institute of America, 1660 Stewart Street, Santa Monica, California 90404 ANTHONY R. KAMPF Mineralogy Section, Natural History Museum of Los Angeles County, 900 Exposition Blvd., Los Angeles, California 90007 AND GEORGE R. ROSSMAN Department of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125, USA ABSTRACT. A crystal of painite discovered in 1979 in a structure and reported its space group as P63. parcel of rough gem spinel from Burma represents the Powder diffraction data for the 1979 crystal were third known crystal of the species. This crystal is similar to obtained using a Debye-Scherrer camera and the type crystal in most respects. Chemical analyses of Cu-Kcz radiation. They confirmed its identity and both the new crystal and the type crystal confirmed the least squares refinement provided the cell constants essential constituents reported by Moore and Araki (1976) and showed in addition the presence of trace given in Table I. These are slightly larger than the amounts of Fe, Cr, V, Ti, Na, and Hf. Optical absorption cell constants determined by Claringbull et al. spectra suggest that the red colour of painite is caused (1957) and Moore and Araki (1976) for the type principally by Cr 3§ and V3 +. crystal. KEYWORDS: painite, new data, colour, Mogok, Burma. PAINITE is one of the rarest minerals, known Table I. Physical properties and unit previously in only two crystals. This paper cell parameters of painite describes a third known crystal of the species, and Type painite 1 1979 painite provides additional data for the type specimen.
    [Show full text]
  • Our-Grading-Standards-V1-6-May
    GRADING STANDARDS VERSION 1.6 – MAY 2019 2 1 DE BEERS GROUP INSTITUTE OF DIAMONDS GRADING STANDARDS — VERSION 1.6 MAY 2019 DE BEERS GROUP INSTITUTE OF DIAMONDS GRADING STANDARDS — VERSION 1.6 MAY 2019 Contents 1 Introduction: the science behind the magic 2 1.1 De Beers Group Institute of Diamonds grading 3 1.1.1 Carat 3 1.1.2 Colour 3 1.1.3 Clarity 3 1.1.4 Cut Grade 3 1.2 De Beers Group Institute of Diamonds production control software 4 1.3 Grading integrity controls 4 2 De Beers Group Institute of Diamonds grading methods 5 2.1.1 Introduction 5 2.2 Colour grading 7 2.3 Clarity grading 10 2.4 Cut grade 30 2.4.1 Proportions 30 2.4.2 Finish grading 40 3 De Beers Group Institute of Diamonds and laser 57 3.1.1 Laser and clarity enhancements 57 3.1.2 Penetrative, internal laser accidents 59 4 Diamond Grading Report 60 4.1.1 The 4Cs of diamonds 60 4.1.2 Grading summary 60 5 Clarity treatments 62 5.1.1 K M 62 5.1.2 Fracture filling 63 5.1.3 Laser drilling 64 5.1.4 Coating 65 6 Summary 66 7 Change log 67 Appendix: 68 Table, crown and pavilion angle proportions charts 68 2 1 DE BEERS GROUP INSTITUTE OF DIAMONDS GRADING STANDARDS — VERSION 1.6 MAY 2019 DE BEERS GROUP INSTITUTE OF DIAMONDS GRADING STANDARDS — VERSION 1.6 MAY 2019 1 Introduction: the science behind the magic At De Beers Group Institute of Diamonds (formerly International Institute of Diamond Grading and Research), we understand the science of diamonds.
    [Show full text]
  • A Specific Gravity Index for Minerats
    A SPECIFICGRAVITY INDEX FOR MINERATS c. A. MURSKyI ern R. M. THOMPSON, Un'fuersityof Bri.ti,sh Col,umb,in,Voncouver, Canad,a This work was undertaken in order to provide a practical, and as far as possible,a complete list of specific gravities of minerals. An accurate speciflc cravity determination can usually be made quickly and this information when combined with other physical properties commonly leads to rapid mineral identification. Early complete but now outdated specific gravity lists are those of Miers given in his mineralogy textbook (1902),and Spencer(M,i,n. Mag.,2!, pp. 382-865,I}ZZ). A more recent list by Hurlbut (Dana's Manuatr of M,i,neral,ogy,LgE2) is incomplete and others are limited to rock forming minerals,Trdger (Tabel,l,enntr-optischen Best'i,mmungd,er geste,i,nsb.ildend,en M,ineral,e, 1952) and Morey (Encycto- ped,iaof Cherni,cal,Technol,ogy, Vol. 12, 19b4). In his mineral identification tables, smith (rd,entifi,cati,onand. qual,itatioe cherai,cal,anal,ys'i,s of mineral,s,second edition, New york, 19bB) groups minerals on the basis of specificgravity but in each of the twelve groups the minerals are listed in order of decreasinghardness. The present work should not be regarded as an index of all known minerals as the specificgravities of many minerals are unknown or known only approximately and are omitted from the current list. The list, in order of increasing specific gravity, includes all minerals without regard to other physical properties or to chemical composition. The designation I or II after the name indicates that the mineral falls in the classesof minerals describedin Dana Systemof M'ineralogyEdition 7, volume I (Native elements, sulphides, oxides, etc.) or II (Halides, carbonates, etc.) (L944 and 1951).
    [Show full text]
  • The Crystal Structure of Painite Cazrb[Al9o18] Revisited
    ARMBRUSTER ET AL.: CRYSTAL STRUCTURE OF PAINITE 611 American Mineralogist, Volume 89, pages 610–613, 2004 The crystal structure of painite CaZrB[Al9O18] revisited THOMAS ARMBRUSTER,1,* NICOLA DÖBELIN,1 ADOLF PERETTI,2 DETLEF GÜNTHER,3 ERIC REUSSER,4 AND BERNARD GROBÉTY5 1Laboratorium für chemische mineralogische Kristallographie, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland 2GRS Gemresearch Swisslab Ltd., Hirschmattstrasse 6, CH-6003 Luzern, Switzerland 3Laboratory of Inorganic Chemistry—Elemental and Trace Analysis ETH Hönggerberg, HCI, G113, CH-8093 Zürich, Switzerland 4Institute of Mineralogy and Petrography, Sonneggstrasse, 5 ETH Zentrum, CH-8092 Zürich, Switzerland 5Department of Geosciences, University of Fribourg, Pérolles, CH-1700 Fribourg, Switzerland ABSTRACT The crystal structure of the rare hexagonal mineral painite [a = 8.724(1), c = 8.464(2) Å] from Mogok (Myanmar), with the ideal composition CaZrB[Al9O18], was re-determined by single-crystal X-ray diffraction. Structure refinements were performed in space groups P63/m and P63. The cen- trosymmetric P63/m model yielded excellent agreement (R1 = 1.44%, 1189 reflections > σ2 Iobs, 54 parameters) with the observed diffraction data without any unusual atomic displacement parameters, thus the acentric P63 model was rejected. A previous structural study claimed that painite was non- centrosymmetric and differed from the related structures of jeremejevite B5[ 3Al6(OH)3O15] and fluoborite B3[Mg9(F,OH)9O9] in having lower symmetry. The structure of painite comprises a framework of AlO6 octahedra that features two types of channels parallel to the c axis. One channel has a trigonal cross-section and is occupied by threefold coordinated B and Zr in sixfold prismatic coordination.
    [Show full text]
  • Winter 2007 Gems & Gemology
    G EMS & G VOLUME XLIII WINTER 2007 EMOLOGY CVD Synthetic Diamonds Canary Tourmaline W Fluorescence Spectroscopy INTER Napoleon Necklace 2007 P AGES 291–408 V OLUME 43 N O. 4 THE QUARTERLY JOURNAL OF THE GEMOLOGICAL INSTITUTE OF AMERICA ® Winter 2007 VOLUME 43, NO. 4 291 LETTERS ________ FEATURE ARTICLES _____________ 294 Latest-Generation CVD-Grown Synthetic Diamonds from Apollo Diamond Inc. Wuyi Wang, Matthew S. Hall, Kyaw Soe Moe, Joshua Tower, and Thomas M. Moses Presents the gemological and spectroscopic properties of Apollo’s latest products, which show significant improvements in size, color, and clarity. 314 Yellow Mn-rich Tourmaline from the Canary Mining Area, Zambia pg. 295 Carat Points Brendan M. Laurs, William B. Simmons, George R. Rossman, Eric A. Fritz, John I. Koivula, Björn Anckar, and Alexander U. Falster Explores the vivid “canary” yellow elbaite from the Lundazi District of eastern Zambia, the most important source of this tourmaline. 332 Fluorescence Spectra of Colored Diamonds Using a Rapid, Mobile Spectrometer Sally Eaton-Magaña, Jeffrey E. Post, Peter J. Heaney, Roy A. Walters, Christopher M. Breeding, and James E. Butler Reports on the use of fluorescence spectroscopy to characterize colored diamonds from the Aurora Butterfly and other collections. NOTES AND NEW TECHNIQUES ________ 352 An Examination of the Napoleon Diamond Necklace Eloïse Gaillou and Jeffrey E. Post pg. 329 Provides a history and gemological characterization of this historic necklace. REGULAR FEATURES _____________________ 358 Lab Notes Apatite in spessartine • Atypical photoluminescence feature in a type IIa diamond • Diamond with “holiday” inclusions • Diamond with large etch channels containing iron sulfides • Black diamond with an oriented etch channel • The pareidolia of diamonds • Notable emerald carving • Gold coated onyx • Double-star sapphire • Imitation turquoise 366 Gem News International Record auction prices for diamonds • Namibian diamond mining pg.
    [Show full text]
  • Spinel from Mogok, Myanmar—A Detailed Inclusion Study by Raman
    FEATURE ARTICLE Spinel from Mogok, Myanmar—A Detailed Inclusion Study by Raman Microspectroscopy and Scanning Electron Microscopy Myint Myat Phyo, Eva Bieler, Leander Franz, Walter Balmer and Michael S. Krzemnicki ABSTRACT: Mineral inclusions within 100 gem-quality spinels from both primary marble and secondary alluvial mining sites within Myanmar's Mogok Valley were analysed using Raman microspectroscopy and scanning electron microscopy (including backscattered-electron imaging and energy-dispersive spectroscopy). The samples ranged from pink to red, orangey pink to orangey red, and grey to purplish grey. We identified a number of inclusions that are reported here for the first time in Mogok spinel: amphibole (presumably pargasite), anatase, baddeleyite, boehmite, brucite, chlorite, clinohumite, clinopyroxene, diaspore, geikielite, goethite, halite, marcasite, molybdenite, periclase and pyrrhotite. We also found several minerals that were previously known as inclusions in Mogok spinel, including anhydrite, apatite, carbonates (calcite, dolomite and magnesite), chondrodite, elemental sulphur, graphite, iron oxides or iron hydroxides, phlogopite and zircon. We further differentiated the occurrence of inclusions in spinel from different mining sites in Mogok to assess whether these mineral assemblages can enhance our understanding of the geological origin of these gems and whether the inclusions can help separate Mogok spinels from those of other marble-related deposits worldwide. The Journal of Gemmology, 36(5), 2019, pp. 418–435, http://doi.org/10.15506/JoG.2019.36.5.418 © 2019 Gem-A (The Gemmological Association of Great Britain) ince ancient times, gem-quality spinel (ideally imperial jewels, two of which were later integrated into MgAl2O4) has been appreciated for its range British royal jewels (the Black Prince’s ‘Ruby’ and the of colour and often exceptional clarity, and Timur ‘Ruby’; see also Pardieu & Hughes 2008; Yavorskyy today spinel is the second most important and & Hughes 2010; Truong 2017).
    [Show full text]
  • Mohsen Manutchehr-Danai Dictionary of Gems and Gemology Mohsen Manutchehr-Danai
    Mohsen Manutchehr-Danai Dictionary of Gems and Gemology Mohsen Manutchehr-Danai Dictionary of Gems and Gemology 2nd extended and revised edition With approx. 25 000 entries, 1 500 figures and 42 tables Author Professor Dr. Mohsen Manutchehr-Danai Dr. Johann-Maier-Straße 1 93049 Regensburg Germany Library of Congress Control Number: 2004116870 ISBN 3-540-23970-7 Springer Berlin Heidelberg New York This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitations, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplica- tion of this publication or parts thereof is permitted only under the provisions of the German Copy- right Law of September 9, 1965, in its current version, and permission for use must always be ob- tained from Springer. Violations are liable to prosecution under the German Copyright Law. Springer is a part of Springer Science+Business Media springeronline.com © Springer-Verlag Berlin Heidelberg 2005 Printed in Germany The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: Erich Kirchner, Heidelberg Typesetting: Camera ready by the author Production: Luisa Tonarelli Printing and binding: Stürtz, Würzburg Printed on acid-free paper 30/2132/LT – 5 4 3 2 1 0 Preface to the Second Edition The worldwide acceptance of the first edition of this book encouraged me to exten- sively revise and extend the second edition.
    [Show full text]
  • Volume 20 / No. 7-8 / 1987
    Volume 20 Nos. 7 & 8 July & October 1987 TheJournal of Gemmology GEMMOLOGICAL ASSOCIATION OF GREAT BRITAIN OFFICERS AND COUNCIL President: *Sir Frank Claringbull, Ph.D., F.lnst.P., FGS Vice-Presidents: J. R. H. Chisholm, M.A., FGA R. K. Mitchell, FGA Chairman: *D. J. Callaghan, FGA Vice-Chairman: *N. W. Deeks, FGA Honorary Treasurer: *N. B. Israel, FGA Members elected to Council: *A. J. Allnutt, M.Sc., J. A. W. Hodgkinson, FGA *J. B. Nelson, Ph.D., Ph.D., FGA D. Inkersole, FGA FRMS, F.Inst.P., FGA *E. M. Bruton, FGA B. Jackson, FGA W. Nowak, C.Eng., *C. R. Cavey, FGA *E. A. Jobbins, B.Sc., C.Eng., F.R.Ae.S., FGA L. F. Cole, FGA FIMM, FGA M. J. Q'Donoghue, P. J. E. Daly, B.Sc., C. B. Jones, FGA MA, FGS, FGA FGA *G. H. Jones, B.Sc., Ph.D., *P. G. Read, C.Eng., *A. E. Farn, FGA FGA MIEE, MIERE, FGA A. J. French, FGA D.G.Kent,FGA A. W. R. Round, FGA *R. R. Harding, B.Sc., D. M. Larcher, FGA E. Stern, FGA D.Phil, FGA D. Morgan, FGA *C. H. Winter, FGA J. W. Harris, B.Sc., M.Sc., Ph.D. * Members of the Executive Committee Branch Chairmen: Midlands Branch: P. J. West, FGA North-West Branch: S. G. Hill, FGA South Yorkshire & District Branch: G. A. Massie~ FGA Examiners: A. J. Allnutt, M.Sc., Ph.D., FGA D. G. Kent, FGA E. M. Bruton, FGA P. Sadler, B.Sc., FGS, FGA A. E. Farn, FGA K.
    [Show full text]
  • ^Ejournal of Gemmology
    Volume 20 No. 4 October 1986 GAGTL EDU Set 3 ^eJournal of Gemmology GEMMOLOGICAL ASSOCIATION OF GREAT BRITAIN OFFICERS AND COUNCIL President: Sir Frank Claringbull Ph. D., F. Inst. P ., F. G. S. Vice-Presidents: J. R. H. Chisholm, M.A., F.G.A. R. K. Mitchell, F.G.A. Chairman: D. J. Callaghan, F.G.A. Vice-Chairman: N. W. Deeks, F.G.A. Honorary Treasurer: N. B. Israel, F.G .A. FellO'Ws elected to Council: C. R. Cavey B. Jackson M. J. O'Donoghue, L. F. Cole C. B. Jones M. A., F.G.S. R. W. Croydon D. M. Larcher P. G. Read, C.Eng., P. J. E. Daly, B.Sc. D. Morgan M. I.K E., M.LE.R.E. A. J. French G. Neary A. W. R. Round S. E. Hiscox J. B. Nelson, Ph.D., F.R.M.S., E. Stern J. A. W. Hodgkinson F. Inst.P., F.G.S. C. H. Winter D. Inkersole W. Nowak, C.Eng., F.R.Ae.S. Branch Chairmen: Midlands Branch: P. West, F.G.A. North-West Branch: S. Hill, F.G.A. South Yurkshire & District Branch: J. L Reynolds, F.G.A. Examiners: E. A. Jobbins, B.Sc., F.I.M.M., F.G.A. A. J. Allnutt, M.Sc., Ph.D., F.G.A. R. R. Harding, B. Sc., D .PhiL, F.G .A. G. H. Jones, B.Sc., Ph.D., F.G.A. D. G, Kent, F.G.A. E. M. Bruton, F.G.A. P. Sadler,B.Sc., F.G.S., F.G.A.
    [Show full text]
  • Gems and Placers—A Genetic Relationship Par Excellence
    Article Gems and Placers—A Genetic Relationship Par Excellence Dill Harald G. Mineralogical Department, Gottfried-Wilhelm-Leibniz University, Welfengarten 1, D-30167 Hannover, Germany; [email protected] Received: 30 August 2018; Accepted: 15 October 2018; Published: 19 October 2018 Abstract: Gemstones form in metamorphic, magmatic, and sedimentary rocks. In sedimentary units, these minerals were emplaced by organic and inorganic chemical processes and also found in clastic deposits as a result of weathering, erosion, transport, and deposition leading to what is called the formation of placer deposits. Of the approximately 150 gemstones, roughly 40 can be recovered from placer deposits for a profit after having passed through the “natural processing plant” encompassing the aforementioned stages in an aquatic and aeolian regime. It is mainly the group of heavy minerals that plays the major part among the placer-type gemstones (almandine, apatite, (chrome) diopside, (chrome) tourmaline, chrysoberyl, demantoid, diamond, enstatite, hessonite, hiddenite, kornerupine, kunzite, kyanite, peridote, pyrope, rhodolite, spessartine, (chrome) titanite, spinel, ruby, sapphire, padparaja, tanzanite, zoisite, topaz, tsavorite, and zircon). Silica and beryl, both light minerals by definition (minerals with a density less than 2.8–2.9 g/cm3, minerals with a density greater than this are called heavy minerals, also sometimes abbreviated to “heavies”. This technical term has no connotation as to the presence or absence of heavy metals), can also appear in some placers and won for a profit (agate, amethyst, citrine, emerald, quartz, rose quartz, smoky quartz, morganite, and aquamarine, beryl). This is also true for the fossilized tree resin, which has a density similar to the light minerals.
    [Show full text]
  • Diamond Clarity Scale Guide
    Diamond Clarity Scale Guide Buckram and contrite Carson foreknew almost playfully, though Lukas shaft his majesty quash. One-piece Deryl andpinged Londony some sunhatsClair grieved and candlingquite perceptibly his perchers but imposts so abusively! her puddler Deuced purposefully. Bernhard still disemboguing: premosaic An h color grade clarity diamond guide on the flash does the surface The diamond and then tested by taking more graders who conceal their own findings and soul note any clarity characteristics. In the best way to the majority of lustre, really interesting names for this gemstone available use loupes or treatment is fairly common. A cavity to diamond clarity grade and bare it will cancel the overall appearance of fine diamond engagement ring. When diamonds clarity scale was this page and scales and effort. The term VS is used for diamonds in which it is difficult for a qualified observer, under observation conditions as described, to find either a few somewhat larger internal characteristics or several very small ones. Because it comes down to avoid diamonds are perpetual, we have reduced by no internal characteristics like a diamond online diamond in. URL and Selector in the configuration of the extension. Diamonds without such impurities are very rare. The 4Cs Carat Color Clarity and Cut Kay Kay Jewelers. Couples looking at round, oval, princess, radiant, heart, and pear can consider G and H color grades for a great value! The wheat is far outdated that. Why do we do this? However, such diamonds may or may not cover surface flaws or blemishes. In these cases, since each individual inclusion is very small, blue diamond looks clean to watch naked eye.
    [Show full text]