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Preface As a junior rockhound and professional mineralogist at Brigham Young University and several foreign campuses, I have enjoyed a life-time love affair with minerals, especially the pretty ones. Since my retirement, I have taught a general education cultural class entitled: “the Science and History of Gems and Precious Things” which is open to anyone of any background. I teach the class just because I want to and have the luxury of teaching students who learn just because they want to. I have students from almost every discipline in the university and senior citizens from the surrounding community. Freed from the scrutiny of competing colleagues, I enjoy the luxury of investigating and teaching whatever interests me without the limitations of their approval, current research or of scientific rigor. I write this book just because I want to and I write to those who will read it just because they want to and who wish to understand some basic concepts of mineralogy and geology, as they apply in the world of pretty minerals. A jeweler I know is more a businessman than a scientist. The success of his jewelry store depends more on his skill in economics, salesmanship and marketing than on his understanding of the product he sells. He could sell insurance, used autos, hamburgers or body lotions with equal enthusiasm, but he has chosen to sell a luxury item which sells well only in good economic times and only to prosperous people. It’s a clean business with little manual labor and he gets to associate with the “upper classes” which tend to be cultured, educated and rich. My friend’s costumer buys gems to assuage his vanity and impress his acquaintances and he wants to know everything about his purchase so he can explain why he invested so much in something that can be visually duplicated in glass and brass. He will expect the jeweler to have the answers and to 1 weave a romantic story punctuated with astounding scientific facts and historical intrigue. If my jeweler friend prospers, he will hire an expert graduate gemologist to supply the answers or he will limit his sales to diamonds and Lladro figurines. Diamonds are “safe”, and everyone must have an engagement diamond because DeBeers says so. The diamond business is organized, regulated and readily accessible and my friend is afraid to launch into the exotic and uncertain world of colored stones and the treasures of earlier times and distant places. He may well handle “created” ruby, sapphire and emerald, but natural gems require risk and understanding that he doesn’t have. Most of his customers prefer “pretty” to “natural” anyway. My friend and his costumers appreciate quality and uniqueness in direct proportion to their knowledge and understanding, and I write for those few who would know and understand. This book is not a treatise on gem identification or the use of gemological instruments, as there are numerous books and manuals on those subjects. All methods of gem testing yield useful information but fall short only in offering a satisfying explanation of what it all means. My friend is intimidated by Greek letters, chemical formulas and mathematical equations, and I have kept them to a minimum, but they are the language of those who understand, and only a little of such language can make my friend look good. A mineral is usually defined as a chemical compound, usually with a definite chemical formula, and usually a crystalline structure, but with the firm understanding that it is created by the processes of inorganic nature. In the hands of an expert, complex x-ray diffraction can reveal the exact position of each atom in a crystal structure, and, in the hands of an expert, various spectroscopic procedures can reveal an exact chemical composition, complete with minor trace elements. I can only pray that this volume never falls into the hands of an expert, for he will pick 2 it apart for its over simplification and broad generalizations but, in the hands of my jeweler friend, this book may open to him the world of pretty minerals and give him the simple explanations and facts for those who care to know. William Revell Phillips – PhD (Mineralogy) Gemstones have fascinated people for thousands of years because of their beauty, rarity and monetary value. However, a true understanding of gemstones and their properties has only come about in the past two centuries resulting from the developing science of geology and mineralogy and an increasing need to distinguish natural gemstones from those that are treated or grown in the laboratory. As a research scientist at the Gemological Institute of America (GIA) for more than 25 years, I have been closely involved with studying a wide variety of gem materials using modern analytical equipment and methods as part of our research effort to meet the ongoing challenges of accurate gem identification. There are numerous books that describe minerals, and a number that report on the distinctive properties of gemstones, but there is often little overlap between these two subjects. There are almost no books that bridge this knowledge gap and present a more detailed mineralogical description of the gem minerals, along with a clear explanation of basic concepts of interest from both mineralogy and geology. James E. Shigley – PhD (Geology) 3