Stones and Gems," I introduced a chapter on Pearls. 

 But within the last few years so much information 

 has accumulated, that I felt it impossible to do 

 justice to the Pearl in any other way than in a 

 separate volume. Moreover, the fact that a Pearl, 

 although composed mainly of carbonate of lime, is 

 after all an organic product, renders it desirable 

 to remove it from association with true minerals. 

 Accordingly in the fourth edition of '' Precious Stones 

 and Gems," I was induced to omit the description 

 of Pearls, and to promise that the subject should 

 be separately dealt with in a special work. That 

 promise I have now the satisfaction of fulfilling. 



When 1 first took the matter in hand, I had 

 no idea of the amount of labour which would be 

 involved in the production of such a work. The 

 study has, however, been a source of much pleasure 

 to myself, and I trust that the perusal of the results 

 set forth in this volume, will be equally a source 

 of gratification to the reader. Although I cannot 

 for a moment hope that the work is anything like 

 complete in all its details, yet I may venture to 

 remark that I have spared no pains in collecting and 

 arranging my materials, and that my information 

 has in many cases been derived from original sources. 

 At the same time, the work is not put forth as a 

 scientific treatise, but rather as a practical guide, 



