For professional or competition-grade sets, you must ensure the boules are made of carbon steel or stainless steel with a specific hardness rating (usually 35 to 45 HRC) to prevent excessive denting. The weight should range between 650g and 800g, and the diameter between 70.5mm and 80mm, adhering to FIPJP (Fédération Internationale de Pétanque et Jeu Provençal) standards. Additionally, verify the balancing accuracy, as high-quality boules should have an internal weight displacement of less than 1.3% of the ball's weight.