When selecting leather cover buckles, the quality of both the base metal and the leather covering is paramount. For the base metal, prioritize zinc alloy or brass over iron to ensure rust resistance and durability. For the leather covering, you must distinguish between genuine leather (top-grain or split), which offers a premium feel and longevity, and PU/synthetic leather, which is more cost-effective and offers better color consistency. Ensure the leather thickness is calibrated (usually 0.5mm to 0.8mm) to allow for a clean wrap around the buckle frame without bulkiness.