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Pearl grading explained

By The Perfect Pearls editors · Updated · How we check our facts

GIA created its 7 Pearl Value Factors for the same reason it created the 4Cs of diamond quality: to give everyone the same simple words for describing quality. The seven are size, shape, color, luster, surface, nacre and matching.

The seven factors

Size

For round and near-round pearls, the diameter in millimeters. Other shapes are measured by length and width.

Shape

Seven basic shapes in three groups: spherical (round, near-round), symmetrical (button, drop, oval) and asymmetrical (semi-baroque, baroque). Spherical pearls are the most valued, and symmetrical drops are also sought after.

Terms: Round, Near-round, Button, Drop, Oval, Semi-baroque, Baroque.

Color

Three parts: bodycolor (the dominant overall color), overtone (translucent colors lying over the bodycolor) and orient (iridescent rainbow colors shimmering on or just below the surface).

Terms: Bodycolor, Overtone, Orient.

Luster

The intensity of light reflected from the surface. GIA grades it from Excellent to Poor.

Terms: Excellent, Very good, Good, Fair, Poor.

Surface

Blemishes and irregularities confined to the surface. GIA uses Clean, Lightly Spotted, Moderately Spotted and Heavily Spotted.

Terms: Clean, Lightly spotted, Moderately spotted, Heavily spotted.

Nacre

Nacre builds the pearl layer after layer. GIA checks that a cultured pearl's nacre is not too thin or damaged, so the pearl is durable.

Matching

How uniform the pearls are in a strand, a pair of earrings or any piece with more than one pearl. Graded Excellent to Poor, or Not applicable.

Terms: Excellent, Very good, Good, Fair, Poor.

What about AAA, AA and A?

You will see letter grades like AAA on pearl listings. GIA describes quality in words rather than letters, using the terms above. Letter grades are each seller's own scale, so an AAA from one shop is not the same as an AAA from another. Ask what the letters mean in GIA's terms: what is the luster, how spotted is the surface, how well matched is the strand?

Which factors matter most to you

  • For a classic strand: shape, luster and matching.
  • For earrings: matching between the two pearls, then luster and surface.
  • For baroque pearls: shape matters less; luster and surface do the work.
  • For any cultured pearl: nacre. Thin nacre can wear through to the bead.

Try it on a pearl you own with the pearl quality checker, or play with luster, overtone and shape in Pearl Studio.

Sources

Frequently asked questions

What are the 7 pearl value factors?

Size, shape, color, luster, surface, nacre and matching, as defined by GIA.

What is the most important factor in pearl quality?

GIA does not rank them, but luster is what makes a pearl glow, shape drives the price of round strands, and nacre decides how long a cultured pearl lasts.

What does AAA mean for pearls?

It is a seller's own letter grade, not a GIA grade. Different sellers use different scales, so ask what it means for luster, surface, shape and matching.

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