What Determines The Quality of A Pearl?

You may have seen Pearls referred to by “grade”:  A, AA, AA+, and AAA.  But how is that grade determined?  Much like the 4 C’s of Diamonds, there are established benchmarks to determine the quality of pearls.  Six factors are evaluated in order to determine the quality and therefore the value of pearls.  Those factors are size, shape, color, surface, nacre and luster.

Some of those factors are more straightforward than others – take size, for example.  When all other value factors are equal, larger pearls are rarer and more valuable than smaller pearls of the same type.  Pearls are measured by their diameter in millimeters.  Even a one millimeter increase in pearl size is a substantial jump in both appearance and value.

Shape is also fairly easy to understand .  A perfectly round pearl is the most difficult shape to culture, making it the rarest cultured pearl shape.  Again, if all other factors are equal, a perfectly round pearl is generally the most valuable. There are some shapes that are exceptions to that rule though. If well-formed, a pear, oval, or baroque (irregularly shaped) cultured pearl can also be valuable.  And while Baroque pearls can be lustrous and appealing, they will typically cost less than round pearls.  They are sometimes known as Potato Pearls.

Pearls are found in a wide range of colors, although all pearl colors tend to be soft or muted.  The color is described by three components, Pearl color can have three components. The body color is the pearl’s dominant overall color. Overtone is one or more translucent colors that lie over a pearl’s body color. And orient is a shimmer of iridescent rainbow colors on or just below a pearl’s surface. All pearls display body color, but only some show overtone, orient, or both.

The value of a color is largely tied to the current trends – if a color is in demand, it will become more valuable.  Most people automatically picture a white Akoya cultured pearl as it is the pearl most commonly used in necklaces.  Some Tahitian saltwater cultured pearls have a color intensity that’s almost like neon lights.  And a Black Tahitian Pearl is not in fact black – generally they are charcoal grey, silver, or dark green.

Most pearls never achieve perfection. Imperfections on the pearls surface determine it’s surface quality.  Some might have abrasions that look like a series of scratches on the surface, or an irregular ridge that looks like a crease or wrinkle.  The more imperfections present, the more they will detract from the look of the pearls, decreasing value significantly.  Those imperfections also compromise the structure of the Pearl, making it weaker and  Small imperfections can sometimes be hidden with a mounting or a drill hole.

Luster and nacre quality are closely related.

Nacre is the natural substance that a mollusk secretes to protect itself from irritants such as shell fragments, parasites or implanted beads. It is a strong, resilient material; lightweight and transparent, allowing light to pass through its surface. A thin layer of nacre will cause the pearl to have a dull, chalky appearance.

The nacre quality affects the luster as well as the durability of the pearl. Nacre is also the beautiful iridescent coating on the inner surface of the mollusk’s shell.  That coating is known, appropriately, as Mother Of Pearl.


Luster is the measure of quantity and quality of light that is reflected from the surface, or just under the surface of a pearl. It is what gives a natural or cultured pearl its unique beauty. The luster of good quality pearls is sharp and bright. You should be able to see your reflection clearly on the surface of a pearl. Any pearl that appears too white, dull or chalky, is of low quality.

  • Excellent – Reflections appear bright and sharp
  • Very Good – Reflections appear bright and near sharp
  • Good – Reflections are bright but not sharp, and slightly hazy around the edges
  • Fair – Reflections are weak and blurred
  • Poor – Reflections are dim and diffused

Within a pearl type, when other value factors are equal, the higher the luster, the more valuable the pearl.

“Matching”  A jewelry designer will sometimes deliberately mix colors, shapes, and sizes for unique effects.  For most pearl strands, earrings, or other multiple-pearl jewelry, the pearls should match in all the quality factors, especially size.  The better the matching, the more valuable the piece will be.

At Grants Jewelry, we can get pearls of any type and color.  Traditional strands are sold in 18″ lengths, with AA+ quality Akoya Cultured Pearl Strands starting at $4,700 per strand.  Contact Susan today to create the perfect pearl necklace for you!  Call (212) 398-1256 or email [email protected].

Sources:  GIA.edu, Wikipedia

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