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A. H. Church Almandine alumina amethyst Apophyllite aquamarine axinite beauty beryl bordered brilliant brilliant-cut brown brownish cabochon carat carbuncle cat's-eye chatoyant chrysoberyl claw mount cloth coloured stones colourless contains coronet mount corundum crocidolite culet cut and polished cut en cabochon diam diamond dichroiscope emerald enamel engraved Essonite faceted felspar garnet gem-stones gems gold grains gray greenish hardness Hope catalogue Illustrations Iolite iron jargoon jewellery jewels Labradorite Lapis-lazuli light lime liquid LONDON lustre magnesia metal minerals moonstone Museum nearly oblong opal opaque openwork mount optical oval oxide pale pearl peculiar peridot phenakite pink plain mount Plate pleiochroism polarized precious stones prism prismatic properties purple Pyrites qualities Quartz refraction rich rock crystal roses ruby sapphire set in silver Silica specific gravity specimens spinel Spodumene step-cut Streeter thick topaz tourmaline TOWNSHEND COLLECTION translucent transparent turquoise twin colours varieties violet weight yellow Zircon
Page 17 - But a caution as to the necessity in all specific gravity experiments of getting rid of air-bubbles may not be out of place. To attain this end boiled water should be used, and if mechanical contrivances fail (a feather or sable pencil) then the liquid and stone should be placed under the receiver of an air-pump and the air exhausted. Details concerning the specific gravity of each kind of precious stone will be found in Chapter VII.