Because pearls are an organic jewel, there are many different surface characteristics that can develop. When considering purchasing a piece of fine pearl jewelry, you should look for the following imperfections:

Abrasion: The pearl is damaged, and this results in a series of scratches.
Bump: Bulges, blisters, or welts that are very small. Too small to effect the overall shape of the pearl.
Chip: A cavity on a pearl’s surface.
Crack: A break or fracture in the nacre or the nucleus that reaches to the surface of the pearl.
Flat: Otherwise spherical or symmetrical, one section of the pearl is flat. This is too small to affect the overall shape.
Gap: An area where the nucleus is not covered by the nacre.
Pit: Indentations and/or depressions. These can either be individual or in a group.
Scratch: A thin groove or depression in a pearl’s surface.
Spot: Darker, lighter or dull area when compared to the surrounding adjacent nacre.
Wrinkle: Irregular ridge or crease on the pearl’s surface.

These are basically all the types of blemishes that one might find on an inferior pearl. When sorted, pearls are viewed with these imperfections in mind. These degrees or ratings are:

Clean AAA Quality – Either blemish-free (spotless), or very small surface characteristics that are difficult to see, even to a trained observer. Look for detail guaranteeing 95% blemish free. Pearl necklaces of this quality are highly beautiful and the most valuable.

Lightly Blemished AA+ Quality – Minor surface blemishes are spotted when inspected by a trained observer. Look for detail guaranteeing 90% blemish free. Differences are only noticeable under very close examination or by a Gemologist, and will not detract from their beauty to the casual observer.

Moderately Blemished AA Quality – Pearls show noticeable surface characteristics.

Heavily Blemished A, B and C Qualities – Obvious surface irregularities are easily picked out. Also, the durability of the pearl may be affected.