New York: Cupples & Leon Company, (1927). Hardcover first edition - The first book in this boys adventure series, also known as The Jewel Series, since each adventure has the boys involved in finding different gemstones. "Malcolm Edwards and his son Ralph are adventurers with ample means for following up their interest in jewel clues. In this book they form a party of five, including Jimmy Stone and Bret Hartson, boys of Ralph's age, and a shrewd level-headed sailor named Stanley Greene, They find a valley of diamonds in the heart of Africa." Probably a first edition - lists only the first 3 titles in the beginning of the book all issued in1927 as a "starter set" as was common with juvenile series at the time. Glossy frontispiece. 211 pp.