corundum, instruments, spectroscope, color.4, properties.3, gems

Read surveys gemmological instruments through their operating principles, practical applications and selected commercial designs, linking the physical properties used in gemstone identification with the equipment employed to measure them. The book begins with diagnostic characteristics and the preparation and handling of specimens, then covers inspection aids, colour, refractive index, birefringence, optical character, dispersion, reflectivity, specific gravity, spectra, luminescence, hardness and thermal conductivity. These subjects lead into the identification of synthetic gems and simulants, experimental instruments, diamond sorting and grading, research laboratory equipment and miscellaneous accessories. The scope extends from familiar hand lenses, microscopes, refractometers, polariscopes and spectroscopes to specialized laboratory methods. Diamond testing receives particular attention through a separate chapter on thermal conductivity, reflecting the identification problems associated with cubic zirconia. The treatment also includes microscopy and photography, equipment for grading polished diamonds, and techniques available to research gemmologists. Appendices provide manufacturers’ and suppliers’ addresses, gemstone constants and characteristic inclusions. The second edition substantially expands the 1978 original, adding 101 pages and increasing the range of instruments described. A major change is the inclusion of comparative evaluations, giving readers more assistance in judging equipment rather than simply identifying available models. The author discusses advantages and disadvantages where instruments have been available for examination, while acknowledging that not every item described could be tested. A comparative value guide supplies a framework for assessing the relative cost of similar equipment. New material covers photomicrography and experimental apparatus, including Read’s own computer system for gemstone identification, and the treatment of synthetic gems and simulants is revised. Contemporary reviewers particularly emphasize the broader equipment coverage, the usefulness of the comparative assessments and price guide, and the extensive photographs and line illustrations. Chapter bibliographies, reference tables and supplier lists strengthen its practical reference function. The volume brings together instrument descriptions, explanations and purchasing comparisons for readers who need to select equipment and apply it to gemstone examination, while documenting the expanding role of electronics and experimental methods in gemmology during the early 1980s.