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[Orchid] [Rare eBooks] Gemstones and Their Distinctive Characters
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Orchid Friday, January 18, 2013
   
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    New in our Digital Antique Books Library.....

    ..................................................... 

    Gemstones and Their Distinctive Characters 
    by G. F. Herbert Smith, 1912

    http://www.ganoksin.com/gnkurl/ep7zxt

    This 1912 book is one of the foundational books for gemology. At 364
    information packed pages this is worth its weight in gold, or
    gemstones. An essential read for all gemologists, and goldsmiths,
    jewelry store staff etc. It lays out the principles and science of
    gemology. Any jeweler would find it interesting and it belongs in
    every gemologist's library. The myriad stories about gems, history
    and rumour are really intriguing. 

    Very solid, wonderful illustrations and images. A truly important
    book. It was written in response to a burgeoning variety of
    imitations, fakes and the beginnings of synthesized materials. An
    attempt was made to make the science understandable and transparent,
    not to be just the jargon loaded `incantations of a wizard' for an
    average person. 

    The table of contents is huge. 

    The book is broken into several discrete chapters and sections. 

    The Characters of Gemstones: Crystalline form, reflection,
    refraction and dispersion, measurement of refractive indices, luster
    and sheen, double refraction, absorption effects: color, dichroism
    etc, specific gravity, hardness and cleavability 

    The Technology of Gemstones: Unit of weight, fashioning of
    gemstones, nomenclature of precious stones, manufactured stones,
    imitation stones. 

    Precious Stones: Diamond, occurrence of diamond, historical
    diamonds, corundum, beryl. 

    Semi-precious stones: topaz, spinel, garnet, hessonite, pyrope,
    rhodolite, almandine, spessartite, andradite, tourmaline, peridot,
    zircon, chrysoberyl, quartz, chalcedony, agate, opal, feldspar,
    turqoiuse, jade, spodumene, iolite, euclase, enstatite, diopside,
    sphene, cassiterite, obsidian (and a bunch more I did not include
    here). 

    Ornamental Stones: Fluor, lapis, sodalite, violane, rhodonite,
    azurite, malachite, thulite, marble, aposphyllite, crysocolla,
    steatite, meershaum, serpentine. 

    Organic Products: Pearl, coral, amber. 

    Tables: chemical composition of gemstones, color of gemstones,
    refractive indices of gemstones. 

    Gems: color dispersion of gemstones, character of the refraction of
    gemstones, dichroism of gemstones, specific gravities of gemstones,
    degrees of hardness of gemstones, data. 

    There is a very good index. 

    The introduction discusses the role of fashion in gem valuation. The
    science discussed is really well advanced. The refractometers and
    polariscopes shown are very early indeed and let the modern
    gemologist know how far we have come. There is a quite a bit of math
    and calculation shown for those with that bent. There are oddities,
    like the luster scale only consisting of 3 steps, so one can see how
    information was incrementally added to the field. Absorption spectra
    are discussed, far earlier than I thought they had been addressed.
    Specific gravity testing in its forms, including things not used any
    more, like a `diffusion column', a single tube with the lighter sg
    liquid poured over the heavier, and then known pieces of different
    specific gravity added. The unknown stone will float between the
    known ones and so can be diagnosed as a certain range. Interesting.
    The thallium use descriptions are very thorough but it is not to be
    used today except in stringent lab conditions as it is too
    dangerous. Another odd test is for electrical properties by blowing
    a mixture of red lead and sulfur powder through a sieve onto a stone
    which gives it static electricity, the different colored powders
    self separating to the ends of the crystal (or stone) accorded to
    their charges. Tourmaline, for instance is extremely strong this
    way. 

    There is a really intriguing history of weighing gemstones and the
    unification of the carat standard, as there were more than a dozen
    different weights all using the word carat used in different places.

    There is an excellent history of cutting gemstones. The chapter on
    nomenclature and where gemstone names came from is very good. There
    is a wonderful section on the history and introduction of man-made
    gems, ruby as early as the 1830's and in the 1880's a large volume
    of reconstituted rubies came on the market. Verneiul's machine came
    into use in 1904, earlier than I had thought. 

    There is exhaustive information on diamonds. History, material, and
    insight into the predatory struggles in South Africa for supremacy
    in the industry. The sections on all the individual gemstones are
    excellent, lots of stories and details not seen often elsewhere. Let
    us just say that most gems are dealt with, and very well at that. A
    modern gemologist could learn a lot from them, as would a jewelry
    store sales person. It is interesting how most of contemporary
    gemology is the same as then, that they knew so much already. The
    biggest changes since then have been sprectroscopy, synthetic gems,
    irradiation. All of this is a huge part of the book. 

    Besides all the science this description of pearls sums up the
    literary flavor of the book: "From that unrecorded day when some
    scantily clothed savage seeking for succulent food opened an oyster
    and found to his astonishment within its shell a delicate silvery
    pellet that shimmered in the light of a tropical sun, down to the
    present day, without intermission, pearl has held a place all its
    own in the rank of jewels." The stories of famous gems, their costs
    and more cannot be found elsewhere. 

    The tables are good, but a bit minimal by today's standards. 

    This book is highly recommended for anyone's collection. 

    File Size: 27.3MB, 364 Pages

    Download the full eBook at the ridiculous price of $5. 
    http://www.ganoksin.com/gnkurl/ep7zxt


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