When sourcing evening dresses, the fabric composition is the primary determinant of value. High-end gowns should utilize mulberry silk, heavy satin (22-30 momme), or premium French lace. For mid-range markets, ensure high-density polyester or chiffon is used to prevent transparency. Pay close attention to internal construction: professional evening wear must include built-in bras, multi-layered crinoline for volume, and at least 4-8 integrated bones (boning) to maintain structure. Inspect the seam allowance; premium suppliers provide a 2-3cm margin to allow for local alterations, which is a critical selling point for retailers.