When sourcing pearls, you must distinguish between Natural, Cultured, Freshwater, and Seawater (Akoya, South Sea, Tahitian) varieties. Value is determined by the '7 Value Factors': Luster (the most important, look for a sharp, mirror-like reflection), Surface Quality (minimal blemishes), Shape (perfectly round commands the highest premium), Color, Size (larger diameters significantly increase price), Nacre Thickness (essential for durability in seawater pearls), and Matching (uniformity in strands).