By Frank B. Wade
Diamonds A Text-Book of Precious Stones
A TEXT-BOOK OF PRECIOUS STONES FOR JEWELERS AND THE GEM-LOVING PUBLIC
by
FRANK B. WADE, B.S.
Head of the Department of Chemistry, Shortridge High School, Indianapolis, Ind. Author of "Diamonds: A Study of the Factors That Govern Their Value"
Illustrated
G. P. Putnam's Sons New York and London The Knickerbocker Press
Copyright, 1918 by Frank B. Wade
First printing, January, 1918 Second " March, 1924
[Device]
Made in the United States of America
PREFACE
In this little text-book the author has tried to combine the trade information which he has gained in his avocation, the study of precious stones, with the scientific knowledge bearing thereon, which his vocation, the teaching of chemistry, has compelled him to master.
In planning and in writing the book, every effort has been made to teach the fundamental principles and methods in use for identifying precious stones, in as natural an order as possible. This has been done in the belief that the necessary information will thus be much more readily acquired by the busy gem merchant or jeweler than would have been the case had the material been arranged in the usual systematic order. The latter is of advantage for quick reference after the fundamentals of the subject have been mastered. It is hoped, however, that the method of presentation used in this book will make easy the acquisition of a knowledge of gemology and that many who have been deterred from studying the subject by a feeling that the difficulties due to their lack of scientific training were insurmountable, will find that they can learn all the science that is really necessary, as they proceed. To that end the discussions have been given in as untechnical language as possible and homely illustrations have in many cases been provided.
Nearly every portion of the subject that a gem merchant needs to know has been considered and there is provided for the interested public much material which will enable them to be more intelligent purchasers of gem-set jewelry, as well as more appreciative lovers of Nature's wonderful mineral masterpieces.
F. B. W.
INDIANAPOLIS, _December 26, 1916_
INTRODUCTION
Because of the rapid increase in knowledge about precious stones on the part of the buying public, it has become necessary for the gem merchant and his clerks and salesmen to know at least as much about the subject of gemology as their better informed customers are likely to know.
In many recent articles in trade papers, attention has been called to this need, and to the provision which Columbia University has made for a course in the study of gems. The action of the National Association of Goldsmiths of Great Britain in providing annual examinations in gemology, and in granting certificates and diplomas to those who successfully pass the examinations, has also been reported, and it has been suggested that some such course should be pursued by jewelers' associations in this country. The greatest difficulty in the way of such formal study among our jewelers and gem merchants is the lack of time for attendance on formal courses, which must necessarily be given at definite times and in definite places.
Table of contents (by pages)
- 1: A Text-Book of Precious Stones for Jewelers and th
- 2: The dealer was doubtless honest
- 3: And cleavability 119 xviii
- 4: Lesson iirefraction explanation of refraction
- 5: The herbert smith refractometer
- 6: 047 Peridot or chrysolite
- 7: Unequal absorption causes dichroism
- 8: But shows hardly any dichroism
- 9: Indicates Ground Glass Stopper
- 10: It is assumed that the jeweler will weigh in carats
- 11: But not touching bottom or sides of the beaker
- 12: Methylene iodide is a heavy liquid sp
- 13: Zircons are strongly doubly refractive
- 14: Although both have vitreous luster
- 15: Sapphire and ruby Mohs called 9
- 16: Being softer than true topaz but harder than quartz
- 17: A small crystal of carborundum
- 18: Carborundum is harder than any gem material but diamond
- 19: As they are both colored stones sphene is usually yellowish
- 20: Spinel ruby more properly ruby spinel
- 21: The color also lacks variety owing to lack of dichroism
- 22: Bluish green beryl aquamarine
- 23: A careful examination of one of these triplets
- 24: Is diamond like as the name demantoid signifies
- 25: The fine gem chrysoberyls known as alexandrites
- 26: The marked dichroism of tourmaline will also help detect it
- 27: And 5 spodumene variety kunzite
- 28: Which is called scientific alexandrite but which has
- 29: Typical defects of natural corundum gems
- 30: Inasmuch as perfect corundum gems are very rare in nature
- 31: A green stone which purported to be an emerald
- 32: Imperfections like those of emerald
- 33: It was therefore judged to be a red spinel
- 34: Which of course abraded the spinel
- 35: Fortunately jargoons are not commonly sold
- 36: As has already been said of jadeite
- 37: There are many different colors of both diamond and corundum
- 38: Belong to the mineral species corundum
- 39: Aluminum oxide and beryllium oxide
- 40: The andradite garnets furnish the brilliant
- 41: Jadeite is a sodium aluminum silicate and nephrite
- 42: Corundum of fine blue color is known as sapphire
- 43: And orange red ones rubicelle
- 44: Some bluish green topaz is said to be sold as aquamarine
- 45: All other colors in zircon should be named simply zircon
- 46: Citrine quartz is probably the best name for this material
- 47: Under it one may purchase jadeite
- 48: Amazonite was originally misnamed
- 49: The Brazilian fields were alluvial
- 50: Most fine rubies come from Burmah
- 51: Have furnished splendid aquamarine and other beryl
- 52: The Arizona rubies are pyrope garnets
- 53: A dark green nephrite comes from New Zealand
- 54: Sometimes used instead of azurite
- 55: How cutting increases brilliancy
- 56: The diamond then readily splits
- 57: Making eight facets and finally 32 facets
- 58: Or even by fine emery or carborundum cloth
- 59: And several sets of facets applied
- 60: As was recommended for sapphires
- 61: Cabochon cut stones usually have a flat base
- 62: Have been used in the cabochon cut
- 63: Small stones sometimes receive fewer facets
- 64: Many of them are silicates of metals
- 65: Garnet takes a keener and more resinous luster than glass
- 66: Usually with the title Swiss Lapis
- 67: Some zircons become completely whitened by this treatment
- 68: Detect the character of a whitened zircon
- 69: Horny substance of organic nature called conchiolin
- 70: Much like the diffraction grating of the physicist
- 71: Thus exposing fresh layers beneath
- 72: 43 avoirdupois grains in a gram
- 73: Pearls have long been acceptable collateral for loans
- 74: The nacre is then prepared from this powder
- 75: By their incorrect degree of hardness
- 76: The balance itself has very delicate knife edges
- 77: 08 grains in the metric carat
- 78: The old carat was approximately
- 79: For use in the manufacture of jewelry
- 80: BIBLIOGRAPHY The student of gems will
- 81: The author has really outdone Bauer
- 82: Is as its name implies a monograph on amber
- 83: Jean Baptiste Tavernier's Voyages
- 84: 209 Cutting of precious stones
- 85: 197 Occurrence of precious stones
- 86: 294 299 Test for double refraction
- 87: 'rubelite' amended to rubellite '
