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Opal Identification and Value

Opal Identification and Value

by Paul B. Downing, Ph.D.

Only $49.95
If you want to learn about opal, this is the book. It's our favorite book about opal. It clearly describes the many different types of opal in language that is easy to understand. Includes information about how opal is identified, valued, mined, cut and used in jewelry. Explains natural, synthetic, simulant, and assembled stone types. This book is a 6 1/2" x 9 1/4" hardcover with 212 pages.

Opal Identification and Value
Table of Contents

  Foreword
vii
  Preface
ix
1. Getting Started
1
    Buying Opal
1
    Valuing Opal
2
    Opal Myths
3
2. About Opal
5
    What Is Gem Opal?
5
    Types of Opals
6
    The Source
6
    Cutting Opal
7
    What Makes a Good Opal?
8
3. Identifying Type
11
    Types of Opal
11
    Determining the Type of an Opal
14
    Identifying Set Stones
20
    Importance of Type
21
    Summary
22
4. Natural, Synthetic, Simulant, Dyed
25
    Synthetic
25
    Simulants or Imitations
26
    Dyed Opal
28
    Conclusion
30
    Summary
30
5. Base Color
31
    What is Base Color?
31
    Definitions of Base Color
33
    Determining Base Color
35
    Black Opal Criteria
36
    Crystal and Semi-Crystal Criteria
40
    Base Color and Value
42
    Summary
43
6. Brightness of Fire
45
    Brightness Standard
45
    Light and Brightness
47
    Developing Brightness Criteria Stones
48
    Judging Brightness
50
    Brightness is Most Important
51
    Summary
52
7. Fire Color
53
    Dominant Color
53
    The Multicolor Rule
56
    Hue, Saturation and Intensity
57
    Judging Fire Color
58
    Summary
58
8. Fire Pattern
59
    Patterns Defined
59
    Harlequin Pattern
61
    Rare Patterns
62
    Picture Stones
66
    Determining Pattern
67
    Summary
68
9. Consistency and Directionality
69
    Consistency
69
    Directionality
70
    Summary
71
10. Cut, Inclusions and Weight
73
    Cut
73
    Weight and Thickness
75
    Weight and Thickness in Calibrated Oval Opals
77
    Inclusions
79
    Cracks and Crazing
79
    Stability
81
    Weight
83
    Cut, Inclusions, Cracks and Value
84
    Summary
84
    Weight Estimation Formula Supplement
86
    Weight Estimation
86
    Standard Shaped Cabochons
86
    Example
87
    Bulge Factor
88
    Freeform Stones
89
11. Properly Set Opals
91
    Protecting the Opal
91
    Custom Designers
93
    Sizing Rings
95
    Inlayed Opal
96
    Summary
97
12. Solid Opal Prices
99
    Opal Prices
99
    Estimating Price
102
    Example
106
    Summary
109
    Characteristics Adjustment Supplement
110
    Price Adjustments
110
13. Boulder Opal Prices
117
    Types of Boulder Opal
118
    Characterizing Boulder Opal
120
    Pricing Boulder Opal
124
    Example
126
    Pricing Boulder Matrix
128
    Andamooka Boulder
129
    Conclusions
129
    Summary
129
    Boulder Adjustment Supplement
130
14. Other Opal Prices
133
    Pricing Doublets
133
    Triplet Prices
136
    Summary
141
15. American and Canadian Opal
143
    American Opal
143
    Nevada Opal
143
    Idaho Opal
145
    Oregon Contra Luz
146
    Arizona Blue Opal
148
    Louisiana Opal
148
    British Columbian Opal
148
    Summary
150
16. Other Locations
151
    Mexican Opal
151
    Brazilian Opal
154
    Honduras Opal
155
    Indonesian Opal
156
    Ethiopian Opal
156
    Summary
157
17. Opal Jewelry
159
    Commercial Settings
159
    Manufactured Jewelry
160
    Designer Jewelry
160
    Designer One-of-a-Kind
161
    Antique / Estate Jewelry
162
    Opal Design Treatments
172
    Summary
178
18. Collections and Carvings
179
    Collector Pieces
179
    Fossils
182
    Carvings
183
    Summary
185
19. Buying Opal
187
    Finding Opal
187
    Buying Opal
189
    Buying in Australia
191
    Summary
192
20. Conclusions
193
 
  Glossary of Terms
195
  Index
200
  Acknowledgements
205
  Photographers
206
  Designer Contacts
207
  Other Books By Paul B. Downing
208
  About the Author
212