viii PREFACE 



appreciate the difficulties connected with such studies. The difficulty of arriving at the 

 necessar\- facts in the preparation of the sketch-maps ^vas particularly great, and these are 

 therefore less numerous than was originally intended. Many of my colleagues have helped 

 me in this matter hy communicating their personal observations or by sending publications 

 bearing upon the subject ; to each of them I return sincere thanks. 



The methods employed in the working of precious stones, and the pin-poses to which the 

 latter are generally applied, have been gone into in some detail, since these stand in the 

 closest relation to the natural cliaracters of the stone. The general part, therefore, includes 

 sections dealing with the forms of cutting, the process of grinding, &c., the information 

 relating to each particular stone being repeated with the special description of that stone. 



In the execution of the work the publishers have as far as possible carried out the 

 wishes of the author. The originals of the coloured plates have been painted by the artistic 

 hand of Herr E. Ohmann of Berlin. Most of the specimens figured are preserved in the 

 mineralogical collection of the Natural History iVIuseum at Berlin. Eor permission to use 

 these, I return my most grateful thanks to the Director of the collection. Professor C. Klein, 

 Privy Councillor of Mines, as also to the Curator, Professor C. Tenne, for the time and 

 trouble he devoted to work connected with the production of the water-colours. No small 

 part of the success of these coloured plates must be ascribed to his active co-operation in 

 their production. Thanks are also due to Director A. Brezina of \'ienna for permission to 

 reproduce the well-kno\vn picture preserved in the Mineralogical Depai-tment of the Natural 

 History Museum, and representing the Kimberley mine, the richest and most famous of the 

 Cape diamond mines, here published for the first time. 



The references to the literature are few, as such references appear out of place in a 

 work primarily intended for general readers. To the narrower circle of mineralogists the 

 author would fain have given more precise and scientific information on innumerable points. 

 For the majority of readers it is desirable that each section should be, as far as possible, 

 complete and independent in itself, so that there is little or no necessity for referring to 

 other parts of the book. This has necessitated the repetition of many statements, but 

 without, it is hoped, the reiteration becoming tiresome. 



The alphabetical index has been made as complete as possible, and includes many 

 terms not to be found in the text ; the meaning of each is given together with the page 

 reference. 



The author has attained his object if he has succeeded in giving to gem-merchants and 

 jewellers, as well as to admirers, of gems, a clear representation of the natural characters and 

 occurrence of precious stones, of the methods according to which they are worked, and of 

 the purposes to which they are applied. If, then, in the pages which follow, the description 

 of certain remarkable minerals should awaken in wider circles a more lively interest in 

 mineralogy as a whole, of which the subject of precious stones is but a part, the author 

 will be gi-atified, and will consider that he is amply repaid for his trouble. 



MAX BAUER. 



Mineralogical Institute of the University, MARiiURo, 

 Autumn 1896. 



