Pearl grading system rates the pearls from grade A to grade D, with A being the highest rating. This system was initiated in French Polynesia for grading South Sea and Tahitian pearls only. This is the reason behind its name which is “Tahitian system”. This pearl grading system is popular in most of the pearl produce countries, while the rest of the pearl manufacturer uses another pearl grading system called “AAA-A”.

Pearl grading from A to D is given as bellow:

Grade A: It is a highest quality pearl along with high luster. It has minor imperfections which are less than 10% of its surface.

Grade B: It has a medium luster with surface flaws less than 30% of the surface area.

Grade C: It has medium luster with surface flaws not more than 60% of the surface.

Grade D: It is extremely low quality pearl having many minor defects over 60% of the surface area with few deep defects on less than 60% of surface area.

Pearls of D grade may have a combination of number of minor and deep flaws over not more than 60% of area. In D grade the luster is extraneous. Pearls having highest luster may also be categorized as D grade pearls if their surface area is stained to this extent. Since pearls bellow D grade are not considered adequate for use in any kind of jewelry making.

Both the pearl grading systems discussed above, basically focus on luster and surface area quality of pearl to decide its grade. Besides these two aspects some other important aspects may be added to determine the quality and value of pearl.

Such a non-graded but still important factor is thickness of the nacre; it determines the durability of pearl that is how durable is the pearl over time. The thickness of the nacre is directly proportional to its durability, thicker is the nacre, and robust is the pearl. The French Polynesian Government has decided that the minimum thickness of nacre should be around 0.8 millimeters. According to their ratings any pearl below this rating will not allowed to be put up in the market for sale.

Of more information on pearl grading, just click here.

Mikimoto pearls are named after a Japanese entrepreneur and inventor that discovered the technique for the commercial production of cultured pearls. These pearls are also referred to a 'hanadama' or 'flower pearls'. These pearls have the highest quality. Mikimoto pearls are cultivated under a strict patented process in the bays of Ise, Honshu Japan. Pearls cultured in this island have highest quality and have become a rich international legacy.

Mikimoto Pearls are graded on the GIA grading system, in this system there are four grades. Highest quality pearls are graded as AAAA, this grade indicates that has complete blemish free surface. It also has sub-grades like AAA1, which indicates a minimally blemished surface. Pearl grades are from AAA to A. All these grades also have sub grades. Pearls with mirror like reflections have of highest quality.

Every pearl jewelry created by Mikimoto is stamped “M” this guarantees quality and genuity. To distinguish between true high quality Mikimoto and other pearls, hold the pearls under a magnifying glass and observe if you see a unique road map or line pattern, if you do, it is a genuine Mikimoto pearl.

Akoya pearls are even finer quality pearls, but they are not Mikimoto pearls. While buying Mikimoto pearls ask for a grading certificate, this will insure you that you are paying for true Mikimoto pearls.