When sourcing high-end footwear, the sole material is paramount; authentic luxury-grade red bottoms typically use genuine Italian leather soles with a high-gloss lacquer finish. Inspect the heel attachment to ensure it is reinforced with steel pins for stability and safety. The upper material should be premium lambskin, calf leather, or high-grade patent leather with no visible glue marks or asymmetrical stitching. For B2B buyers, ensure the heel pitch is ergonomically designed to balance weight distribution, preventing rapid wearer fatigue.