How to do the diamond casino heist in GTA 5 Online begins with gathering a team and selecting your approach. Players can choose between aggressive, stealthy, or a mixed strategy. First, complete the setup missions to gather equipment and intel. After planning, equip your crew and enter the casino during the chosen approach. You’ll need to navigate security, crack safes, and manage guards effectively. Once you secure the diamonds, escape the casino while evading law enforcement. Communication and teamwork are key to successfully completing the heist and maximizing your rewards in the game.