Excellent little volume for the beginner like me. Clearly identifies gems by colour type (so, for example, if you are trying to identify a blue gem you can look quickly at the page for blue-type gems), and then contains individual entries for each which give history, mineralogy, uses, and a table of specifications. Each individual entry also includes photos of the most commonly found cuts of that particular gem for easy identification. Also includes a cursory entry on biologically produced materials such as mother-of-pearl, abalone...