Answer: John Brown, Henry Bright, Jacob Golf and Rudy Lopez
Step-by-step explanation: We know that Henry's last name is Bright so that's one, John's last name starts with B, the only name that starts with b is Brown, now it says that Rudy's last name isn't a precious metal, meaning that the only last name that could be the answer is Lopez, and that leaves us with Jacob who, obviously has Gold as his last name