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. Two major grading systems are in fairly widespread use, and used by nearly every major pearl retailer in the United States: the AAA-A system and the A-D system (also called the Tahitian system).
Even these systems, 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.
Hanadama, AAA & AA+
Gem Grade, AAA & AA+
The Hanadama, AAA, AA, A SystemThis system grades pearls on a scale starting at A - Hanadama grade and was originally designed for Akoya pearls. There is a similar system used for Freshwater pearls but there is no Hanadama grade for Freshwater pearls.
Hanadama: This is a special designation for pearls that have passed the Pearl Science Laboratory of Japans rigorous tests and must be accompanied by the original certificate. Hanadama pearls are tested for a nacre thickness of at least 0.4mm on each side for a total of 0.8mm total nacre thickness. Hanadama pearls must also be nearly flawless with no visible inclusions and an extremely high luster.
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 a nacre thickness (Akoya pearls only) of 0.4mm or higher.
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 thick nacre, still a very nice quality but not quite as nice as AAA or higher.
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.
Pearls that do not fall into the ranking categories above are typically either sold in beading stores, or simply stripped of their nacre, which is then ground to be used in makeup and other beautifying aids.
The A - D System (or Tahitian System)This system grades pearls on a scale from A to D, with A being the highest grade. This is the system used in French Polynesia (based on a government standard there) to grade Tahitian pearls. It is therefore sometimes referred to as the "Tahitian system." To make your shopping experience easier at PearlsOfJoy.com we utilize the AAA-A system for all of our pearls.
A: The highest-quality pearl, with very high luster with only minor imperfections over less than 10% of its surface. These imperfections are then used as marks for drill holes.
B: High or medium luster. Surface may have some visible imperfections, but over no more than 30% of its area.
C: Medium luster with surface defects over not more than 60% of the surface area.
D: May have many slight defects, but no deep ones, spread over 60% of its surface; or deep defects over no more than 60% of its surface; or a combination of minor and deep defects over no more than 60% of its surface. In this grade of pearl, the luster is irrelevant. Even the most lustrous pearls will be graded D if their surface is blemished to this extent.
Pearls below D grade are considered not acceptable for use in jewelry.
Both of the grading systems described above focus primarily on the luster and surface quality of the pearl to determine its grade. But keep in mind that other factors also contribute to the quality of any pearl. One of the most important is the thickness of the nacre, which often determines how durable the pearl will be over time. The thicker the nacre, the stronger and longer-lasting the pearl (provided it is treated well, of course!).
For Tahitian pearls, the government of French Polynesia has set a minimum nacre thickness of 0.8 millimeters. Any pearls with nacre of less than that thickness are not allowed to be sold. Keeping in mind that Tahitian pearls tend to be larger than many other pearls (such as Akoyas), you can use this rule as a guideline when evaluating your own potential pearl purchases.
Shop For Pearls