When sourcing custom watches, the movement type is the most critical factor; choose between Swiss movements (ETA, Sellita) for luxury positioning, Japanese movements (Miyota, Seiko) for reliability and value, or Chinese movements for cost-efficiency. Additionally, specify the case material, prioritizing 316L Stainless Steel for its corrosion resistance and hypoallergenic properties. For the watch face, Sapphire Crystal is the industry standard for scratch resistance, while Mineral Glass serves as a budget-friendly alternative. Ensure the Water Resistance (ATM) rating aligns with your target market, typically 3ATM for dress watches and 10ATM or higher for sports/diver watches.