Unfortunately, the pearl industry as a whole has not adopted a universally used standard grading system. Instead, the specific grading system used often depends upon the specific jeweler. The major grading system in fairly widespread use, and used by nearly every major pearl retailer in the United States is the AAA-A system.
Even this system, however, can become misleading if a seller uses terms from the grading system (such as "AAA"), but uses them to describe a different quality pearl than that which the system is generally understood to be describing. Or a seller could use a term not in the grading system (such as "AAAA" or "AAA+") to make it appear that the pearl is beyond even the highest standard quality -- when in reality, that seller's "AAAA" pearls are actually equivalent to the more-common "AAA" grade, and his "AAA" pearls might only be equivalent to the commonly used "AA."
For reasons such as these, it's extremely important when purchasing pearls to be absolutely certain of the meaning of any descriptive terms used by the seller. If possible, ask to see a written description of each grading term, so that you know exactly what the grade implies. Reputable jewelers will be happy to comply with such a request. Only in this way will you be able to determine if the price the seller is asking is reasonable.
The AAA - A System
This system grades pearls on a scale from AAA to A, with AAA - or commonly known as gem-quality - being the highest grade:AAA: The highest-quality pearl, virtually flawless. The surface will have a very high luster, and at least 95% of the surface will be free from any type of defect. The pearl will be perfectly round, and have a mirror-like luster, and total nacre thickness (Akoya pearls only) of at least .75mm.
AA: The surface will have a very high luster, and at least 75% of the surface will be free from any type of defect. The luster will be very high, and have a total nacre thickness (Akoya pearls only) of at least .5mm.
A: This is the lowest jewelry-grade pearl, with a lower luster and/or more than 25% of the surface showing defects. In many cases, if the pearl is being mounted into a piece of jewelry, it can be mounted so that the defects are hidden -- thus providing a lovely jewelry piece at a lesser price. This quality has a chalky appearance and thin nacre, typically of .25mm or less. This thin nacre is due to early harvesting of the pearl.
More Akoya Pearl Information:
Akoya Pearl BasicsAkoya Pearl Overtones
Akoya Pearl Grading System
Akoya Pearl Size Guideline
