A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public

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  2/7/11 12:35 PM 1 of 104 The Project Gutenberg eBook of A Text-Book of Precious Stones for Jewelersand the Gem-Loving Public, by Frank Bertram WadeThis eBook is for the use of anyone anywhere at no cost and withalmost no restrictions whatsoever. You may copy it, give it away orre-use it under the terms of the Project Gutenberg License included with this eBook or online at www.gutenberg.orgTitle: A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public Author: Frank Bertram WadeRelease Date: February 12, 2009 [eBook #28058]Language: English***START OF THE PROJECT GUTENBERG EBOOK A TEXT-BOOK OF PRECIOUS STONES FORJEWELERS AND THE GEM-LOVING PUBLIC***E-text prepared by Peter Vachuska, Chuck Greif, Stephen Blundell, and theProject Gutenberg Online Distributed Proofreading Team ( Project Gutenberg also has an HTML version of thisfile which includes the srcinal illustrations.See 28058-h.htm or Frank B. WadeDiamonds A Text-Book of Precious Stones A TEXT-BOOK OF PRECIOUS STONES FOR JEWELERS AND THE GEM-LOVING PUBLICbyFRANK B. WADE, B.S.Head of the Department of Chemistry, Shortridge HighSchool, Indianapolis, Ind. Author of Diamonds: A Study of the Factors That  2/7/11 12:35 PM 2 of 104 Govern Their Value IllustratedG. P. Putnam's SonsNew York and LondonThe Knickerbocker PressCopyright, 1918byFrank B. WadeFirst printing, January, 1918Second March, 1924[Device]Made in the United States of AmericaPREFACEIn this little text-book the author has tried to combine the tradeinformation which he has gained in his avocation, the study of preciousstones, with the scientific knowledge bearing thereon, which hisvocation, the teaching of chemistry, has compelled him to master.In planning and in writing the book, every effort has been made to teachthe fundamental principles and methods in use for identifying preciousstones, in as natural an order as possible. This has been done in thebelief that the necessary information will thus be much more readilyacquired by the busy gem merchant or jeweler than would have been thecase had the material been arranged in the usual systematic order. Thelatter is of advantage for quick reference after the fundamentals of thesubject have been mastered. It is hoped, however, that the method ofpresentation used in this book will make easy the acquisition of aknowledge of gemology and that many who have been deterred from studyingthe subject by a feeling that the difficulties due to their lack ofscientific training were insurmountable, will find that they can learnall the science that is really necessary, as they proceed. To that endthe discussions have been given in as untechnical language as possibleand homely illustrations have in many cases been provided.Nearly every portion of the subject that a gem merchant needs to knowhas been considered and there is provided for the interested public much material which will enable them to be more intelligent purchasers ofgem-set jewelry, as well as more appreciative lovers of Nature's wonderful mineral masterpieces.F. B. W.INDIANAPOLIS,  2/7/11 12:35 PM 3 of 104 _December 26, 1916_ INTRODUCTIONBecause of the rapid increase in knowledge about precious stones on thepart of the buying public, it has become necessary for the gem merchantand his clerks and salesmen to know at least as much about the subjectof gemology as their better informed customers are likely to know.In many recent articles in trade papers, attention has been called tothis need, and to the provision which Columbia University has made for acourse in the study of gems. The action of the National Association ofGoldsmiths of Great Britain in providing annual examinations ingemology, and in granting certificates and diplomas to those whosuccessfully pass the examinations, has also been reported, and it hasbeen suggested that some such course should be pursued by jewelers'associations in this country. The greatest difficulty in the way of suchformal study among our jewelers and gem merchants is the lack of timefor attendance on formal courses, which must necessarily be given atdefinite times and in definite places. As a diamond salesman was heard to say recently: The boss said he wanted me to take in that course at Columbia, but he didn't tell me howI was going to do it. Here I am a thousand miles from Columbia, and it was only six weeks ago that he was telling me I ought to take thatcourse. I can't stay around New York all the time. Similarly those whose work keeps them in New York might object that their hours ofemployment prevented attendance on day courses, and that distance from the university and fatigue prevent attendance on night courses. Thegreat mass of gem dealers in other cities must also be considered.It will therefore be the endeavor of this book to provide guidance forthose who really want to make themselves more efficient in the gem business, but who have felt that they needed something in the way ofsuggestion regarding what to attempt, and how to go about it.Study of the sort that will be suggested can be pursued in spare moments, on street cars or elevated trains, in waiting rooms, or inone's room at night. It will astonish many to find how much can beaccomplished by consistently utilizing spare moments. Booker T.Washington is said to have written in such spare time practically allthat he has published.For the practical study of the gems themselves, which is an absolutelyessential part of the work, those actually engaged in the trade havebetter opportunities than any school could give and, except during rushseasons, there is plenty of time during business hours for such study.No intelligent employer will begrudge such use of time for which he ispaying, if the thing be done in reason and with a serious view toimprovement. The frequent application of what is acquired, asopportunity offers, in connection with ordinary salesmanship, will helpfix the subject and at the same time increase sales.Many gem dealers have been deterred from beginning a study of gemsbecause of the seeming difficulties in connection with the scientificdetermination of the different varieties of stones. Now science isnothing but boiled-down common sense, and a bold front will soon  2/7/11 12:35 PM 4 of 104 convince one that most of the difficulties are more apparent than real.Such minor difficulties as exist will be approached in such a mannerthat a little effort will overcome them. For those who are willing to do more work, this book will suggest definite portions of particular books, which are easily available, for reference reading and study--but thelessons themselves will attempt to teach the essential things in assimple a manner as is possible.Perhaps the first essential for the gem merchant is to be able surely todistinguish the various stones from one another and from synthetic andimitation stones.That such ability is much needed will be clear to anyone who in castinga backward glance over his experience recalls the many serious mistakesthat have come to his knowledge. Many more have doubtless occurred without detection. Several times recently the author has come acrosscases where large dealers have been mistaken in their determination ofcolored stones, particularly emeralds. Only the other day a ring wasbrought to me that had been bought for a genuine emerald ring after thebuyer had taken it to one of the dealers in his city and had paid for anexamination of it, which had resulted in its being declared genuine. Onexamining the stone with a lens of only moderate power, several roundair bubbles were noted in it, and on barely touching it with a file it was easily scratched. The material was green glass. Now, what was saidabout the dealer who sold it and the one who appraised it may beimagined. The long chain of adverse influence which will be put inaction against those dealers, even though the one who sold the stone makes good the loss, is something that can be ill afforded by anydealer, and all this might have been avoided by even a rudimentaryknowledge of the means of distinguishing precious stones. The dealer wasdoubtless honest, but, through carelessness or ignorance, was himselfdeceived.Our first few lessons will therefore be concerned chiefly with learningthe best means of telling the different stones from one another.CONTENTSPAGEPREFACE iiiLESSONI.--HOW STONES ARE DISTINGUISHED FROM ONE ANOTHER 1II.--REFRACTION 4III.--DOUBLE REFRACTION 8IV.--ABSORPTION AND DICHROISM 15V.--SPECIFIC GRAVITY 23VI.--SPECIFIC GRAVITY DETERMINATIONS 31VII.--LUSTER AND OTHER REFLECTION EFFECTS 38VIII.--HARDNESS 47


Nov 16, 2017
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