"Natural Gemstones" by Geological Survey is a scientific publication likely written in the late 20th century. The book provides an overview of natural gemstones, discussing their classification as precious or semiprecious, as well as the geologic environments in which they form. It serves as a comprehensive resource for collectors, hobbyists, and anyone interested in the identification and evaluation of gemstones. The content of the book spans various topics related to gemstones, including descriptions of different types of minerals, their formation processes, and specific properties such as hardness and specific gravity. It explains the various geological environments where gemstones are found, such as pegmatites and stream gravels, highlighting that these natural treasures are often rare and scattered. Additionally, the publication provides insights into organic gemstones, gemstone valuation, and tips for prospective buyers to navigate the market wisely, especially concerning synthetic gems. The book acts as an essential guide for amateur gemologists and collectors looking to deepen their understanding of the world of gemstones. (This is an automatically generated summary.)