How Do You Judge Pearl Quality?

The same seven factors decide the value of a natural or cultured pearl, or of a piece of pearl jewelry.¹ GIA’s laboratory calls them the 7 Pearl Value Factors and lists them as size, shape, color, nacre, luster, surface and matching.²

The seven value factors#

• Size. When the other factors are equal, larger pearls are rarer and more valuable than smaller pearls of the same type.¹ South Sea cultured pearls are the largest of the cultured types.³
• Shape. Pearls come in eight basic shapes: round, semi-round, button, drop, pear, oval, baroque and circled.³ Round is the most difficult shape to culture, which makes it the rarest cultured pearl shape, though well-formed pear, oval and baroque pearls are also prized.¹ See baroque pearls.
• Color. A pearl’s color has up to three parts: bodycolor, its main color; overtone, translucent color over the bodycolor; and orient, a shimmer of rainbow colors on or just below the surface. Supply and demand set the value of a given color at any time, and fashion and cultural traditions shape which colors people prefer.¹ See color and overtone.
• Luster. Luster might be the most important factor. GIA describes five levels, from excellent, with bright, sharp reflections, to poor, with dim, diffused ones.¹ See luster.
• Surface. Most pearls show some blemishes. Few or minor ones, or ones hidden by the drill hole or a mounting, have less effect, but many or severe ones can hurt durability and sharply lower value.¹
• Nacre. Nacre quality and luster go together. A bead visible under the nacre, or a dull, chalky look, means thin nacre, which affects luster and durability.¹
• Matching. In strands, earrings and other jewelry with several pearls, the pearls should usually match in all the other factors.¹

Why judging pearls is hard#

Pearl quality is harder to pin down than a diamond’s. CIBJO notes that pearl quality factors are more complex and delicate than those of any other gem, that personal preferences such as shape and color play a part, and that necklaces add the further question of matching.⁴

Names are not standard either. There are no unified standards for pearl color names, and each vendor uses its own.⁴ The grading section explains how labs and producers turn these factors into grades, and the quality self-check walks you through looking at your own pearls.