When sourcing BBQ charcoal, quality is determined by carbon content, moisture levels, and ash production. High-quality charcoal should have a fixed carbon content of at least 75-85% to ensure a long and steady burn. You should request a proximate analysis report to verify that the moisture content is below 8% (to prevent sparking and difficulty lighting) and the ash content is under 3-5% (to prevent airflow blockage in the grill). Additionally, check for calorific value, which should ideally be above 7,000 kcal/kg for professional-grade grilling.