The combination of surface brilliance and a deep-seated glow, the luster of a good-quality pearl should be bright, not dull. Your reflection should be seen clearly on the surface of a pearl. Any pearl that looks too chalky or dull indicates low quality.
Cleanliness of the pearl surface refers to the absence of disfiguring spots, bumps or cracks. A pearl with a clean surface will have a higher value than a spotted, bumpy or cracked one.
Since cultured pearls are grown by oysters and subject to the whims of Mother Nature, it is very rare to find a perfectly round pearl. While rounder pearls are more valuable, asymmetrical, or baroque, pearls have a unique charm and are available at a more moderate cost.
Rose Silver/White Cream Gold Blue/Gray Cultured pearls occur in colors from rosé to black. While color is a matter of preference, rosé or silver/white pearls tend to look best on fair skin tones, while cream and gold-tone pearls are flattering to darker complexions.
Measured by their diameter in millimeters, the average cultured pearls sold today are between 7 and 71/2 millimeters. Generally, the larger the pearl, the more valuable it will be.
For more information visit the official Jewelry Information Center.