62, 64, 82, 130, 144, 169, 193

Garnet, Pyrope, 144, 168, 192, 193

Glass, 62, 142

Glass imitations, 81, 237-249

"Golcondas," 180

"Grain base," price of pearls per, 271

Hardness, 47-54, 55-59, 113

Hardness and wearing qualities, 119-132

Hardness, Mohs's scale of, 48-51

Hardness, table of, 54

Hardness, test of, 51-54, 58

"Heliodor," 165

"Hope Blue" diamond, 91

Hyacinth, 166

Imitations of precious stones, 237-249

Imitations of pearls, 277-282

Imperfections, 111

Imperfections in corundum gems, 101

Imperfections in glass, 81

Imperfections in scientific stones, 104

Jacinth, 166

Jade, 128, 147, 175, 197

Jadeite, 128, 197

Jargoons, 166

Jasper, 128, 172

Kunzite, 195

Lapis lazuli, 132, 177, 199

Labradorite, 176

Luster, 38-42

"Make" of diamonds, 205-207

"Make" of precious stones, 220

Malachite, 132, 148, 177, 199

Metallic oxides, 137

Mineral species, 133-148

"Mixed cut" stones, 236

Mohs's scale of hardness, 48-51

Moonstone, 44, 45, 131, 146, 176, 198

Morganite, 165

"Nacre," 280

Naming precious stones, 149-163, 164-178

Nephrite, 129, 197

Occurrence of precious stones, 179-200

"Olivine" (_see_ Demantoid Garnet)

Olivine, 83, 176

Onyx, 172

Opal, 44, 131, 139, 173

Ordinary ray, 16

"Orient" of pearls, 261

"Oriental" stones, 84, 156

"Paste" gems, 142, 237-241

Pearls, 258-276

"Peeling" pearls, 265

Peridot, 8, 130, 176, 198

Pink stones, 93

"Pinked" topaz, 250

Plasma, 172

Polishing of diamonds, 210

Polishing of precious stones, 218

Prase, 138, 172

Properties, definition of, 1

Purple stones, 94

Quartz, aventurine, 171

Quartz, citrine, 161, 171, 195, 196

Quartz gems, 45, 127, 171, 195, 197

Reflection, total, 204

Refraction, 4

Refraction, double, 8-13

Refraction, double, test for, 10, 112

Refractometer, 5

Rhodolite garnet, 168

"Roman" pearls, 279

Rose cut stones, 231

Rose quartz, 171, 197

Rubellite, 93

Ruby, 12, 67, 69, 153, 154, 186

Ruby, scientific, 99-108

Sapphires, 63, 87, 88, 155, 187

Sard, 172

Sardonyx, 172

Scientific stones, 99-108

Scientific stones, defects in, 104

Scientific stones, tests for, 99-108

Siam rubies, 154

Silicates, 141

"Silk" in rubies, 117

Slitting of precious stones, 213

South African diamonds,