Buyers should distinguish between pure copper, bronze, and brass. While 'copper medal' is a broad term, most high-quality medals are made of H65 or H85 brass due to its excellent balance of malleability and corrosion resistance. Ensure the thickness is at least 2mm to 5mm to provide a premium hand-feel and structural integrity. For high-end awards, verify the electroplating process (e.g., real gold, silver, or antique copper plating) and ensure a clear lacquer coating is applied to prevent oxidation and tarnishing over time.