Gemmology

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Elsevier, Oct 22, 2013 - Nature - 370 pages
Gemmology is a text for students preparing for the Gemmological Association's Preliminary and Diploma examinations. The book is more expansive and up-to-date than the author's earlier book, Beginner's Guide to Gemmology.
The book deals with the practical and theoretical sides of gemmology. Tracing the background and science of gemmology, the book covers the gem material, geological formation, and occurrence of gemstones on the earth. The composition of gemstones from the atoms, elements, molecules, and compounds comprising them is analyzed, and the relationship between chemical composition and durability of the stone is explained. The basics of crystallography is mentioned as a tool toward understanding gemmology after which cleavage, parting, and fracture are done. A gemstone's durability and hardness and how the latter influences engineering tests and the mining techniques are compared. An important test technique to identify unmounted stones is the measure of specific gravity using displacement measurement methods and hydrostatic methods. After more descriptive details are given in identification of gemstones, whether these are synthetic or simulants, through a comprehensive explanation of the materials found in these other gemstones, the fashioning, through shaping or polishing, of gemstones is explained. Emphasis is given on the critical angle in which light rays pass in different rock densities, and then the cutting styles, gemstone polishing, and grading are discussed.
Students studying for the Gemmological Association's Preliminary and Diploma examinations, jewelers, lapidarists, and diamond cutters, as well as those engaged in the hobby of gemmology, will find this book helpful and full of information toward their endeavors and hobbies.
 

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Contents

Chapter 1 Introduction
1
Chapter 2 The geological formation and occurrence of gemstones
12
Chapter 3 The chemical composition of gemstones
23
Chapter 4 Crystallography
30
Chapter 5 Cleavage parting and fracture
46
Chapter 6 Hardness
51
Chapter 7 Specific gravity density and relative density
57
Chapter 8 Colour lustre and sheen
72
Chapter 12 Luminescent electrical and thermal properties of gemstones
144
Chapter 13 The hand lens microscope and Chelsea filter
161
Chapter 14 Gemstone enhancement
179
Chapter 15 Synthetic gemstones and gemstone simulants
193
Chapter 16 Distinguishing between synthetic and natural gemstones
217
Chapter 17 Identifying inorganic gemstone simulants
244
Chapter 18 Organic gem materials and their simulants
256
Chapter 19 The fashioning of gemstones
279

Chapter 9 Reflection and refraction
85
Chapter 10 Polarization and pleochroism
114
Chapter 11 Spectroscopy
125
Appendices
302
Index
347
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