The book Chemistry, Properties and Testing of Gemstones by John Mastin is a recognized authority on gemstones. In this book, the author analyzes in detail the chemical properties of various types of gemstones, explains their unique characteristics, and suggests testing methods to determine their authenticity. Mastin provides numerous examples and illustrations that help readers better understand the characteristics of each type of stone. This book is an essential source of information for both gem professionals and hobbyists interested in the subject.