gems, jade, Fischer-Book

Sinkankas: Essentially an encyclopedia of gemstones and technical terms connected with the jewelry trade presented in terse, informative language. There are 80 articles devoted to as many terms, including gemstone varieties as well as species, all in alphabetical order. Each gemstone article provides all essential data on properties, deposits, methods of cutting, uses, and specific retail prices as then current. The folding plates are of great interest and attractively and realistically drawn. The first depicts curiously-shaped rough diamond specimens as well as crystals but it is obvious that Barbot knew little about crystallography because several impossible crystal forms are shown, e.g., a pentagonal dodecahedron, and a 24-faced solid, classical geometrical solids not occurring in actual crystals. Also on this plate are sketches of lapidary apparatus and styles of brilliant and rose cuts. The second plate shows a large number of famous diamonds and the third plate gives several cutting styles of diamonds in addition to a graduated series of brilliants and rose cuts with corresponding carat weights. Noted in the title, Barbot’s “invention” of a diamond decolorizing process is only briefly discussed in vague terms (p. 229) with no details given except to say that heat and several strong chemicals are employed. Readers are encouraged to send in their stones for treatment and several pages are devoted to extolling the benefits to be expected.