I'd waited years for a recent edition of this book, even used, at a reasonable price. Now it's finally affordable as a new hardback.
I was kinda hoping for a book that would let me compare my gemstones to pictures and identify them. This book helped me understand why that kind of book is NOT possible. The best part, for people like me, is the way the many testing techniques and tools are explained, logically and in layman's terms. The book helped me see that learning to use techniques and tools to identify gemstones on my own is possible, and it will undoubtedly help me figure out which tools to invest in first.
Readers familiar with metaphysical uses and astrological correspondences will probably wonder why Schumann chose the sources he did for that type of information, which seem to match neither the traditional nor the esoteric uses. He probably should have stuck to hard science, which is the real strength of this book.