The diamond industry has a standardized system for grading clarify based on a system developed by the GIA(Gemological Institute of America).Ten-power magnification is used. The advantage of having this system is that buyers can communicate what they want anywhere in the world. In addition, written appraisals and quality reports are more meaningful. The GIA has tries to establish such a system for pearls. Their latest system defines four categories of surface quality.
1.Clean----Pearls are blemish-free or contain minute surface characteristics that are very difficult to see by a trained observer.
2.Lightly blemished ---Pearls show minor surface irregularities when examined by a trained observer.
3.Moderately blemished---Pearls show noticeable surface characteristics.
4.Heavily blemished---Pearls show obvious surface irregularities that might affect durability.
Most pearl dealers have their own systems for grading surface quality. Occasionally you’ll come across grades such as AAA, AA, A. Depending on the supplier or store, these grades may refer to the luster, the flaws, a combination of these two factors, or they may include other factors such as shape and nacre thickness. In essence, pearl grades have no meaning except what the seller assigns to them. Therefore, do not rely on grades to compare pearl prices. Examine the pearls yourself, use your own judgment and consider the following.
1.The prominence of the blemished. Visible flaws away from drill holes are more serious than those near the holes. High bumps can be more noticeable than small pits or low bumps.
2.The type of flaws. Chipped or missing nacre is usually more serious than bumps even though it may be less noticeable.
3.The percentage of the pearl surface that is flawed. It’s a lot more serious if 80% of the surface of a pearl is flawed than if only 10% of it is. You need to roll the pearls to check the factor.
4.The percentage of pearls on a strand that are flawed and to what degree. This is a factor that doesn't exist in diamond grading. Pearl grading is more complex. It’s much harder to develop consistent grades for sets of gems than for single gems.