When sourcing unique cards (such as luxury business cards, wedding invitations, or collectible trading cards), you must focus on paper weight (GSM), finishing techniques, and printing precision. For a premium feel, prioritize cardstock between 350gsm and 600gsm. Key finishing technologies include foil stamping (gold/silver/holographic), spot UV coating, embossing/debossing, and laser die-cutting for intricate shapes. Ensure the supplier uses high-resolution offset printing (300+ DPI) or digital indigo printing to guarantee sharp details and color accuracy.