  - Absorption, 53, 59
- Absorption spectra, 59
- Achroite, 220, 221
- Adularia, 255
- Agate, 247
- Akbar Shah diamond, 163
- Alalite, 272
- Albite, 254
- Alexandrite, 54, 60, 233
- Scientific, 122
- Almandine, 60, 214
- Oriental, 112, 172
- spinel, 112, 204
- Amazon-stone, 255
- Amber, 83, 298
- Amethyst, 239, 242
- Oriental, 111, 172, 239
- Anatase, 281
- Andalusite, 274
- Andradite, 216
- Anomalous refraction, 47
- Anorthite, 254
- Apatite, 279
- Apophyllite, 290
- Aquamarine, 184, 193
- Arizona-ruby, 213
- Artificial stones, 124
- Asteria, 38, 177
- Asterism, 38
- Australia stones, 154, 174, 182, 195, 213, 216, 227, 232, 252, 288
- Austrian Yellow diamond, 165
- Aventurine, 240, 241
- Axes, Crystallographic, 9
- Optic, 49
- Axinite, 278
- Azure-quartz, 244
- Azurite, 287
- Balas-ruby, 203
- Barnato, Barnett, 145
- Baroque, Barrok, pearls, 292
- Bastite, 272
- Benitoite, 267
- Berquem, Louis de, 90, 161
- Beryl, 184
- B
90-h-15.htm.html#Page_90" class="pginternal">90
- gauges, 86
- Glaziers’, 135
- mining, 146
- Occurrence of, in—
- Borneo, 154
- Brazil, 139
- German South-West Africa, 155
- India, 138
- New South Wales, 154
- Rhodesia, 155
- South Africa, 139
- Origin of, 151
- -point, 91
- -rose, 92
- -table, 91
- Diamonds, Classification of, 136, 149
- Historical, 157
- Prices of, 135
- Dichroism, 55
- Dichroite, 266
- Dichroscope, 55
- Diffusion column, 65
- Diopside, 272
- Dioptase, 280
- Dispersion, Colour, 20, 24, 97
- Disthene, 273
- Dop, 102
- Double refraction, 28, 40
- Doublet, 125
- Dresden diamond, 171
- Drop-stone, 94
- Duke of Devonshire’s emerald, 191
- Edwardes ruby, 175
- Electrical characters, 82
- Emerald, 89, 184
- Brazilian, 220, 221
- Evening, 225
- Oriental, 111, 172
- Scientific, 122
- Uralian, 216
- Emeraldine, 247
- Emery, 175
- English Dresden diamond, 166
- Enstatite, 271
- Epidote, 275
- Essence d’Orient, 126
- Essonite (Hessonite), 211
- Euclase, 269
- EugÉnie diamond, 164
- Evening emerald, 225
- Excelsior diamond, 167
- Extinction, 45
- Faceting machine, 105
- False topaz, 239
- Felspar, 254
- Fire, 20, 165
- Paste, 47, 124
- Paul I diamond, 171
- Pavilion, 93
- Pavilion facet, 93
- Pear-drop pearls, 292
- Pear-eye pearls, 292
- Pearl, 291
- grain, 86
- imitations, 126
- Pendeloque, 94
- Peridot, 225
- Brazilian, 221
- Ceylonese, 221
- Peruzzi, Vincenzio, 92
- Phenakite, 269
- Pigott diamond, 164
- Pipes, 152
- Pistacite, 275
- Pitt diamond, 100, 159
- Plasma, 247, 264
- Pleochroism, 57
- Pleonaste, 204
- Pliny, 6, 88, 138, 184, 191, 241, 249
- Polar Star diamond, 163
- Polarization, 42
- Porter-Rhodes diamond, 166
- Positive double refraction, 45
- Prase, 240, 247
- Prehnite, 278
- Pycnometer, 75
- Pyrites, 282
- Pyrope, 212
- Quartz, 50, 238
- Quoin facet, 93
- Rainbow-quartz, 240
- Reconstructed stones, 116
- Reef, 144
- Reflection of light, 14
- Refraction of light, 15
- Refractive index, 16
- Refractometer, 22, 50
- Regent diamond, 100, 159
- Retgers’s salt, 69
- Rhodes, Cecil J., 145
- Rhodesia stones, 155, 183, 213, 236
- Rhodolite, 62, 214
- Rhodonite, 287
- Rock-crystal, 97,
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