Flowing Gold by Rex Beach (1877 - 1949)

Unfairly given a dishonorable discharge from the army, Calvin Gray goes to Dallas, where he manages to win the trust of a jeweler and is able to sell a number of diamonds to the newly oil rich Briskows. He makes friends with the family and helps them adjust to their newly found riches. The Briskows, in turn, help him prove false the charges that caused his dismissal from the army. (Summary by Richard Kilmer)