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A. H. Church agate Almandine alumina aluminium Apophyllite Aquamarine artistic axinite beauty beryl blue bordered Brazil brilliant brilliant-cut brown brownish cabochon carat cat's-eye Ceylon Chalcedony chatoyancy chemical Chrysoberyl cinnamon-stone claw mount cloth colourless contains coronet mount corundum crocidolite cut en cabochon Cymophane diam diamond dichroiscope Edition emerald enamel engraved Essonite faceted felspar garnet gem-stones gems gold grains gray greenish hardness Hope catalogue Illustrations indigo Iolite Jargoon jewellery jewels Lapis-lazuli light lime LONDON lustre magnesia Medal metal mineral Moonstone nearly oblong Opal opaque openwork mount optical oval pale pearls peculiar peridot phenakite pink plain mount Plate pleiochroism precious stones Price prism prismatic purple Pyrites qualities Quartz Quartz 80 refraction rich rock crystal roses ruby sapphire set in silver Silica specific gravity specimens spinel Spodumene step-cut Streeter surface thick topaz tourmaline TOWNSHEND COLLECTION translucent transparent turquoise varieties weight yellow yellowish 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.