Rotation of plane of polarization, 50 Rubellite, 220, 223 Rubicelle, 203 Ruby, 98, 110, 172 Balas-, 203 Cape-, 213 Sancy diamond, 161 Sapphire, 98, 110, 172 Brazilian (tourmaline), 221 -quartz, 244 Water- (iolite), 266 Water- (topaz), 201 Sard, 247 Sardonyx, 247 Saussurite, 263 Schorl, 221 Scientific alexandrite, 122 brilliant, 122 emerald, 122 topaz, 121 Scotch topaz, 239 Seed pearls, 294 Serpentine, 289 Setting of gem-stones, 107 Shah diamond, 163 Sheen, 39 Shepherd’s Stone diamond, 163 Siam stones, 180 Siberia and Asiatic Russia stones, 182, 188, 194, 201, 217, 223, 236, 244, 256, 262, 269, 270, 287 Siberite, 221 Siderite, 244 Silver-thallium nitrate, 69 Skew facet, 93 Skill facet, 93 Smoky quartz, 240 Snell’s laws, 16 Soapstone, 288 Sodalite, 286, 287 Sonstadt’s solution, 67 South Africa stones, 139 _et seq._, 166, 167 _et seq._, 213, 232, 244, 264, 271 Spanish topaz, 239 Specific gravity, 63 Specific-gravity bottle, 75 Spectroscope, 59 Spectrum, 20, 25 Spectrum, Absorption, 59 Spessartite, 216 Sphene, 276 Spinel, 203 Spodumene, 265 Spotted stones, 149 Star-facet, 92 Star of Africa diamond, 168 Star of Este diamond, 165 Star of Minas diamond, 169 Star of South Africa diamond, 141, 166 Star of the South diamond, 139, 165 Starstones, 38, 177 Steatite, 288 Step form of cutting, 98 Stewart diamond, 166 Strass, 124 Sunstone, 255 Synthetical stones, 113 Syriam, Syrian, garnet, 215 Table facet, 92 Table form of cutting, 91 Tavernier, J. B., 91, 129, 137, 161, 162, 170 Templet facet, 92 Tetragonal system, 9 Thulite, 289 Tiffany diamond, 171 Tiger’s-eye, 39, 240 Timur ruby, 206 Titanite, 276 Topaz, 197 Brazilian, 197 False, 239 Occidental, 111, 239 Oriental, 111, 173 Scientific, 121 Scotch, 239 Spanish, 239 Topazolite, 216 Total-reflection, 18, 21 Tourmaline, 43, 219 Trap form of cutting, 98 Trichroism, 57 Triclinic system, 12 Triplet, 126 Turquoise, 257 Turquoise-matrix, 258 Tuscany diamond, 165 Twinning, 12, 47 Uniaxial double refraction, 45, 48 57 Uralian emerald, 217 Uvarovite, 218 Variscite, 259 Verdite, 264 Verneuil, A. V. L., 116 Vesuvianite, 274 Victoria diamond, 167 Violane, 287 Wart-pearl, 296 Water (of diamonds), 129 (of pearls), 292