The author, who possesses what is believed to be the most comprehensive private library on this subject, has obtained many references from material which he has been gathering during the past twenty-five years. Many of the types exist in the collection of folk-lore precious stones exhibited at the World’s Columbian Exposition in 1893, and now in the Field Museum of Natural History in Chicago. Other types are drawn from the Morgan Collection exhibited at the Paris Expositions of 1889 and 1900, which, with additions, is now in Morgan Hall, in the American Museum of Natural History, New York City. Other prominent references are the collection of precious stones in the California Midwinter Memorial Museum, in Golden Gate Park, San Francisco; the Tiffany collection of precious stones, exhibited at the Atlanta Exposition of 1894, now in the National Museum in Washington; the collection exhibited at the Pan-American Exposition, and presented to the Musée d’Histoire Naturelle, in Paris, by the late J. Pierpont Morgan; the collection exhibited at the exposition held in Portland, Oregon, in 1905; and the collection of gems and precious stones exhibited at the Jamestown Exposition, 1907. All of these collections, either entirely or very largely, have been formed by the author. Some references to sentiment connected with precious stones are embodied in the little work, now in its 21st edition, entitled: “Natal Stones, Sentiments and Superstitions Associated with Precious Stones,” compiled by the writer, who has examined nearly all the principal collections in the United States, Europe, Mexico, Canada, and Asiatic Russia. For courtesies, information and illustrations, I am indebted to the following, to whom my thanks are due: