Pearl grading system
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
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.
0 comments:
Post a Comment