A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public

A Text-Book of Precious Stones for Jewelers and the Gem-Loving Public, by Frank Bertram Wade, aims, its preface says, to combine the trade information the author has gained in his avocation, the study of precious stones, with the scientific knowledge bearing thereon. The title page lists the author as head of the department of chemistry at Shortridge High School, Indianapolis, Ind. The text describes an instrument called the Herbert-Smith refractometer, with which anyone with a little practice can read the refractive index on the scale within the instrument, for any precious stone that is not too highly refractive.

Under Lesson III on double refraction, the text says that glass and a small number of precious stones (diamond, garnet, and spinel) bend light, while practically all the other stones cause a beam of light on entering them to separate. The text says that some of the wine yellow true topazes lose the yellow but retain the pink component on being gently heated, and that such artificially altered topazes should be sold only for what they are. On scientific precious stones, the text calls The Production and Identification of Artificial Precious Stones, by Noel Heaton, very fine.