Gemstones and Their Distinctive Characters by G. F. Herbert Smith, 1912
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.
Lewton-Brain 2012
File Size: 27.3MB, 364 Pages
