When sourcing wholesale perfume, quality is determined by the concentration of fragrance oils (Parfum, EDP, EDT, or EDC) and the stability of the scent profile. Buyers should request a Certificate of Analysis (COA) and MSDS (Material Safety Data Sheet) to verify chemical composition. Ensure the supplier uses high-grade denatured alcohol and that the fragrance notes (top, middle, and base) remain consistent over time. For OEM/ODM orders, verify the purity of essential oils and the absence of prohibited phthalates.