Escola de Gemmologia - GEMMOLOGY II

 

 

GEMMOLOGY II - Lecture Syllabus
  • A) Descriptive Gemmology 
    • Diamond. Nomenclature. Morphology. Physical properties. Colour and flourescence in diamond. Brilliant cut. Rose cut. Sorting and trading of diamonds. Occurrences and localities. Synthetic material. Treatments. Imitations. 
    • Gem Minerals of the oxides group. Corundum. Nomenclature. Morphology. Physical properties. Synthetic material. Treatments. Imitations. Chrysoberyl. Morphology. Physical properties. Occurrences and localities of this group. 
    • Gem Minerals of the tectosilicates group (I). Quartz. Nomenclature. Morphology. Physical properties. Synthetic material. Treatments. Chalcedony. Nomenclature. Properties. Staining. Opal. Nomenclature. Properties. Cutting. Synthetic material. Imitations. Occurrence and localities of this group. 
    • Gem Minerals of the Tectosilicates group (II). Feldspars. Nomenclature. Morphology. Physical properties. Danburite. Scapolite. Sodalite and Lapis-lazuli. Properties. Imitations. Tugtupite. Occurrences and localities of this group. 
    • Gem Minerals of the inosilicates group: Spodumene, Diopside, Enstatite, Prehnite, Rhodonite, Jade. Nomenclature. Physical properties. Staining. Imitations. Occurrences and localities. 
    • Gem Minerals of the cyclosilicates group. Beryl. Nomenclature. Morphology. Physical properties. Emerald cut. Synthetic material. Treatments. Imitations. Cordierite. Tourmaline. Nomenclature. Morphology. Physical properties. Benitoite. Sugilite. Occurrences and localities of this group. 
    • Gem Minerals of the Sorosilicates group. Axinite, Zoisite and Epidote. Idocrase (Vesuvianite). Kornerupine. 
    • Gem Minerals of the Nesosilicates group (I). Topaz. Nomenclature. Morphology. Physical properties. Treatments. Imitations. Peridot. Nomenclature. Morphology. Physical properties. Occurrence and localities of this group. 
    • Gem Minerals of the Nesosilicates group (II): Datolite. Andalusite, Euclase, Phenakite, Cyanite, Sphene, Dumortierite. 
    • Gem Minerals of the Nesosilicates group (III). Zircon. Nomenclature. Morphology. Physical properties. Heat treatments. The garnet group. Nomenclature. Isomorphism in garnets. Morphology. Physical properties. Occurrence and localities of this group. 
    • Gem Minerals of the Borates group: Sinhalite, Howlite. 
    • Gem Minerals of the phosphates group: Apatite, Brazilianite, Turquoise, Variscite. Morphology. Physical properties. Occurrences and localities. Imitations. 
    • Gem Minerals of the Carbonates group. Azurite. Malachite. Rhodochrosite, Smithsonite. 
    • Gem Minerals of the Halides group: Fluorite. Gem Minerals of the Sulfides group: Pyrite. Physical properties. Occurrence and localities of these groups. 
    • Natural glasses. Volcanic glasses. Physical properties. Tektites. Nomenclature. Origin of Tektites. Physical properties. Occurrence and localities. 
    • Organic gems of animal origin (I). Pearl. Nomenclature. Pearl biology. Physical characteristics. Pearl fisheries and trade. Cultured pearls. Culture and trading. Freshwater pearl: biology, culture and trading. Imitation pearl. Manufacture. Pearl study techniques. 
    • Organic gems of animal origin (II). Ivory. Physical properties. Ivory biology. Imitations. Tortoise-shell. Physical properties. Imitations. Coral. Biology of Coral. Properties. Trading. Imitations. Black coral. Mother-of-pearl. 
    • Organic gems of vegetal origin. Amber: physical properties. Imitations. Origin. Jet: physical properties. Origin. Imitations. 
    • Materials for making imitations. Glass and plastic. Composite stones. 
  • B) General Gemmology 
    • Concept of crystal. Properties of crystalline material. Concept of symmetry. Elements of symmetry. Crystal systems. Crystal morphology. Crystal representation. Miller indices. Crystal habit. Crystal aggregates. Most frequent crystal forms in gems. 
    • Chemical composition and structure. Bond types. Relationship between chemical composition, structure and physical properties. Most important types of structure; examples. Concepts of isomorphism and polymorphism; examples. 
    • Mechanical properties. Hardness: concept. Hardness scales. Application in gemmology. Cleavage: concept. Importance in gemmology, diamond fashioning and lapidary work. Parting. Fracture. 
    • Specific gravity: definition. Determination of specific gravity. Comparative method: heavy liquids. Types of heavy liquids commonly used in gemmology. Precise determination of specific gravity: pycnometer, hydrostatic balance and other methods. 
    • Nature of light. Reflection. Refraction. Descartes'law. Snell's law. Refractive index. Critical angle and total reflection. Lustre and dispersion. 
    • Natural light and polarised light. Methods to obtain polarised light. Polariscope. Optical isotropy and anisotropy in crystals. Birefringence. Uniaxial and biaxial crystals. Optical reference surfaces. 
    • Principle of the refractometer. Measurement of the refractive index. Other methods to measure the refractive index. 
    • Emission and absorption spectra. The spectroscope and its use. Chromophore elements and their relation to the spectra of gems. The more important spectra. 
    • Colour in gems. Allochromatism and idiochromatism. Interference of light. Adularescence. Chatoyancy. Asterism. Orient. Dichroism. Dichroscopic eyepiece. 
    • Morphological study of gems, external and internal appearance. Magnifying glass. Microscope. Types of microscope. Use of the microscope in Gemmology. 
    • Luminescence: fluorescence and phosphorescence. Causes of the phenomenon. Its observation: ultra-violet lamp; triboluminescence, X-ray fluorescence. 
    • Styles of cutting in gems: general considerations. Brilliant cut and its modifications. Emerald cut and its modifications. Other classical styles of cutting. Old styles of cutting. Fancy cuts, new trends. Fashioning of gemstones: general characteristics. 
    • Gemmological nomenclature. Rationalization of trade terms. C.I.B.J.O. Agreements. 
GEMMOLOGY II - Laboratory Syllabus

The practical sessions of this course are intended to study in depth the identification of gemmological materials, both uncut ("rough") and cut, natural and synthetic. In the Practical Laboratory the student has access to the basic apparatus of a gemmological laboratory (refractometer, spectroscope and microscope) and other additional apparatus which he may use when he considers it necessary. 
5-hour Classes, in groups of some 30 students with the assistance of two members of the teaching staff. Students must bring a 10x magnifying glass and a pair of tweezers with a relatively fine point. 

  • Rough material 
  • Ruby and substitutes 
  • Sapphire and substitutes 
  • Emerald and substitutes 
  • Diamond and substitutes 
  • Summary of the above mentioned practicals 
  • Aquamarine, chrysoberyl and spinel 
  • Zircon, topaz and apatite 
  • Quartz, chalcedony and opal 
  • Garnet, tourmaline and peridot 
  • Jade and substitutes 
  • Turquoise, lapis lazuli and feldspars 
  • Exam 
  • Exam comments 
  • Colourless and white stones 
  • Coloured stones, red, pink and violet 
  • Blue coloured stones 
  • Green coloured stones 
  • Orange, yellow and brown stones 
  • 1st group exam 
  • 2nd group exam 
  • Exam comments 
  • Black coloured stones and organic materials 
  • Summary of rough materials 
  • General summary 

Reading List

 

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