CONTENTS 



INTRODUCTION 



1 



FIRST PART 



GENERAL CHARACTERS OF PRECIOUS STONES 



I. NATURAL CHARACTERS AND 

 OCCURRENCE 



A. Chemical Composition 



B. Crystalline Form 



C. Physical Characters 



(a) Specific Gravity 



(i) Cleavage 



(r) Hardness 



(rf) Optical Characters 



1. Transparency 



-!. Lusti'e . 



3. Refraction of Light 



4. Double Refraction of Light 



5. Colour ... 



6. Dichroism 



7. Special Optical Appearances and 



Colour EfPects . 

 («) Thermal, Electrical, and Magnetic 

 Characters 

 1. Thermal Characters 

 "2. Electrical Characters 

 3. Magnetism 



H 

 11 

 11 

 2(i 

 211 

 34 

 34 

 35 

 37 



D. Occurrence of Precious Stones 



II. APPLICATIONS OF PRECIOUS 



STONES 



A. Technical Applications 



B. Application as Jewels 



(ii) Forms of Cutting 

 {h) Process of Cutting 

 (r-) Boring 



(rf) Working on the Lathe 

 ((') Engraving ; Etching 

 Colouring and Burning 

 Mounting and Setting 

 Faults in Precious Stones 

 Artificial Production 

 Counterfeiting 

 Value and Price 



68 



70 

 71 

 72 

 79 

 86 

 85 

 85 

 87 

 89 

 91 

 93 

 94 

 101 



CLASSIFICATION OF PRE- 

 CIOUS STONES . . . 106 



SECOND PART 



SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



