624 



INDEX 



Oriental lapis-lazuli, 438 



opal, 374, 377 



pearls, 597 



ruby, 265 



sapphire, 282 



stones, 70, 264, 292 



topaz (corundum), 293 



turquoise, 389 



Orloff diamond, 249 

 Orthoclase, 425, 428, 429, 431 



-sun-stone, 428 



Osseous amber, 537 



Otto's Kopje diamond mine, 



208 

 Ounce-pearls, 592 

 Ouro Preto (Brazil), topaz, 335 

 Over-ground facets, 80 



Panna (India), diamond, 151 



conglomerate, 142 



Paphos diamonds (quartz), 479 

 Paragon diamonds, 242 



pearls, 592 



Parang (Brazil), diamond, 170 

 Parcel inferior (diamond), 214 

 Partial (India), diamond, 148 

 Pasha of Egypt diamond, 251 

 Paste (glass imitations), 98 

 Pate de riz, 465 

 Paulite, 451 

 Pavilion, 73 

 Pear-pearls, 591 

 Pearl, 585 



imitation, 600 



coloured amber, 537 



-drops, 591 



eyes, 591 



fishing, 594 



-grain (unit of weight), 



104, 593 



-mussel, 598 



-oyster, 594 



Pearly lustre, 37, 589 

 Pelle d'angelo coral, 603, 613 

 Pellegrina (la) pearl, 592 

 Pendeloque, 78 

 Peridote, 404, 405 



Ceylonese (tourmaline), 



372 

 Peristerite, 431 

 Persia, 393, 596 

 Persian Gulf, 596 



turquoise, 393 



Peruvian emerald, 312 

 Phenakite, 326 

 Phosphorescence, 65 



of diamond, 137 



Physical characters, 1 1 

 Piece-pearls, 592 

 -roses, 241 



Piedmontite, 419 



Piedra de la hijada, 466 



Pigeon's-blood red ruby, 265 



Pigments, 56 



Pigott diamond, 251 



Pingos d'agoa (topaz), 330, 334 



Pinites succinifer, 540 



Pink topaz, 332 



Pipe-agate, 513 



Pipes of Kimberley mines, 187 



Piruzeh, 393 



Pistacite = epidote, 417 



Pit-amber, 542 



Pitch-coal, 557 



opal, 385, 386 



Pitt diamond, 250 



Pivot-bearings of watches, bal- 

 ances, etc., 70 



Plagioclase, 425 



Plasma, 510 



Plates (amber), 549 



Play of prismatic colours, 45, 63 



Pleochroism = Dichroism, 59 



Pleonaste, 299 



Pniel (S. Africa), diamond, 180, 

 184 



Point-stones, jj 



Points (diamond crystals), 123 



Polar Star diamond, 249 



Polariscope, 50, 62, 562 



Polarised light, 50 



Polish, degree of, ■^6 



Polishing, process of, 81 



disc, 82 



material, 83 



Porcelain-jasper, 501 



Porter Rhodes diamond, 211, 



253 

 Portrait-stones, 242 

 Prase, 488 



opal, 386 



Precious varieties, 2 



beryl, 308 



coral, 601 



corundum, 263 



opal, 373, 374 



spinel, 295 



Prehnite, 421 



Premier diamond mine, 184 

 Pressed amber, 552 

 Prismatic colours, play of, 43, 



45; 63 

 Pseudo-chrysolite (moldavite), 



449 



diamond (quartz), 479 



Punamu, 464 

 Purple sapphire, 294 

 Pycnite, 329 

 Pycnometer, 12 

 Pyrites, 532 

 Pyroelectricity, 67, 368, 565 



Pyrope, zt,6 _^ 

 Pyrophane, 387 

 Pyrophysalite, 329 

 Pyroxene group, 45 



Quartet, 10 

 Quartz, 471 



avanturine-, 502 



cat's-eye, 491 



ferruginous, 499 



rose-, 488 



sapphire-, 488 



smoky-, 479 



varieties, list of, 474 



with enclosures, 489 



Quebec diamonds (quartz), 479 



RAiNBow-agate, 511 



-quartz, 490 



Ramulkota (India), diamond, 



147 

 Raolconda (India), diamond, 



147 

 Rati, 104 

 Ratnapura (Ceylon), sapphire, 



287 

 Red coral, 601 



Sea, 596, 610 



stones, 570, 580 



Reddish-brown stones, 571 



-yellow stones, 572 



Reef, 187 



Reflection, internal total, 40 



Refraction of light, ■^j 



double, 46, 60 



Refractive co-ef&cient, 38 



index, 38 



indices, table of, 54 



Regent diamond, 75, 250 

 Resin, 535 



opal, 38s 



Resinous lustre, 37 

 Rewah group, 142 

 Rheinkiesel, 477 

 Rhine-quartz, 477 

 Rhodochrosite, 457 

 Rhodolite, 360 

 Rhodonite, 456 

 Rhombic system, 10, 47, 51 

 Riband-agate, 512 



jasper, 501 



Ring-agate, 512 

 Ringsteine, 334 

 Rio Abaete (Brazil), diamond, 



158 

 Ripe pearls, 590 

 River diggings, 182, 1S4 



pearls, 598 



— — -stones (diamond), 186 



