Gemmology is a text for students preparing for the Gemmological Association's Preliminary and Diploma examinations. The book is more expansive and up-to-date than the author's earlier book, Beginner's Guide to Gemmology.
The book deals with the practical and theoretical sides of gemmology. Tracing the background and science of gemmology, the book covers the gem material, geological formation, and occurrence of gemstones on the earth. The composition of gemstones from the atoms, elements, molecules, and compounds comprising them is analyzed, and the relationship between chemical composition and durability of the stone is explained. The basics of crystallography is mentioned as a tool toward understanding gemmology after which cleavage, parting, and fracture are done. A gemstone's durability and hardness and how the latter influences engineering tests and the mining techniques are compared. An important test technique to identify unmounted stones is the measure of specific gravity using displacement measurement methods and hydrostatic methods. After more descriptive details are given in identification of gemstones, whether these are synthetic or simulants, through a comprehensive explanation of the materials found in these other gemstones, the fashioning, through shaping or polishing, of gemstones is explained. Emphasis is given on the critical angle in which light rays pass in different rock densities, and then the cutting styles, gemstone polishing, and grading are discussed.
Students studying for the Gemmological Association's Preliminary and Diploma examinations, jewelers, lapidarists, and diamond cutters, as well as those engaged in the hobby of gemmology, will find this book helpful and full of information toward their endeavors and hobbies.
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Chapter 4 Crystallography
Chapter 5 Cleavage parting and fracture
Chapter 6 Hardness
Chapter 7 Specific gravity density and relative density
Chapter 8 Colour lustre and sheen
Chapter 12 Luminescent electrical and thermal properties of gemstones
Chapter 13 The hand lens microscope and Chelsea filter
Chapter 14 Gemstone enhancement
Chapter 15 Synthetic gemstones and gemstone simulants
Chapter 16 Distinguishing between synthetic and natural gemstones
Chapter 17 Identifying inorganic gemstone simulants
Chapter 18 Organic gem materials and their simulants
Chapter 19 The fashioning of gemstones
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Absorption spectrum alexandrite amber atoms axis bands beryl blue cabochon calcite carats carbon Chapter Chelsea filter chrysoberyl cleavage colour colourless Composition containing corundum critical angle Crystal system Cubic detected diamond simulant diffraction Dispersion double refraction electrons elements Figure filter fluoresce flux-melt Fracture garnet gem materials gemmological gemstone gemstone's glass green hardness heat heavy liquids hexagonal identified illumination immersed inclusions instrument jadeite layers lens light source Luminescence Lustre magnification method microscope minerals Monoclinic Non-crystalline opal opaque optic sign Orthorhombic oxide pavilion facets pink plane Pleochroism polariscope polarized polished prism Prismatic produced quartz rays reflected refraction and optic Refractive index refractometer ruby sapphire shadow edge Specific gravity specimen spectroscope spinel Sri Lanka strontium titanate surface SW UV symmetry synthetic diamonds synthetic emeralds synthetic spinel table facet temperature thermal topaz tourmaline translucent transparent Trigonal twinning variety Verneuil visible Vitreous wavelength X-ray yellow zircon