diamonds, famous diamonds, gems

A popular illustrated survey of diamonds, developed from the diamond exhibit at Chicago’s Century of Progress Exposition, follows the stone from its natural occurrence through mining, cutting, historical ownership and industrial application. The opening chapter describes diamond as crystalline carbon and introduces its atomic structure, crystal forms, cleavage, hardness, brittleness, specific gravity, colour and optical properties. Refraction, internal reflection and dispersion are explained through familiar comparisons, while fluorescence, X-ray behaviour, irradiation effects and methods of distinguishing diamonds from imitations receive additional attention. The geographical account traces production from India and Brazil to the major African fields, with shorter notices of occurrences elsewhere. Particular emphasis falls on South African discoveries, the development of Kimberley and neighbouring mines, and the recovery of diamonds from river gravels and coastal deposits. An elementary geological discussion relates kimberlite pipes to volcanic activity and explains the erosion, transport and concentration of diamonds in secondary deposits. Mining is presented through a descriptive tour of underground operations, including shafts, haulage, drilling, blasting, stoping, ventilation and measures against dust and water. Subsequent processing involves crushing, screening, gravity concentration, grease-table recovery and sorting. The account also describes African mineworkers’ compounds, employment arrangements and precautions against theft, using the paternalistic racial language and assumptions of its period. The cutting chapter outlines the development of faceted styles and explains the relationship between facet angles and optical performance. It follows a rough stone through examination, sawing or cleaving, rounding, mounting and polishing, and discusses the established cutting centres of Amsterdam and Antwerp. Accounts of famous diamonds, including the Kohinoor, Orlov, Hope and Cullinan, combine descriptions of the stones with stories of conquest, royal ownership, theft and recutting. Industrial applications include grinding-wheel dressing, wire-drawing dies, oil nozzles, core drills, stone saws, glass cutters and precision tools. The concluding chapter surveys the entrepreneurs, engineers and financial organisations behind the modern diamond industry, particularly De Beers and the Diamond Corporation. It explicitly defends coordinated marketing and restrictions on supply as safeguards for diamond prices and owners’ accumulated wealth. Photographs, diagrams, historical illustrations, a selected bibliography and an index support an accessible treatment combining scientific explanation, travel narrative, historical anecdote and promotion of diamonds’ beauty, utility and lasting value.