Final Grade


Use the grading obtained for each factor and weigh them according to the previous text. For example, if the grades obtained were: Color-8, Shape-7, Lustre-8, Nacre-8, Blemishes-6, and Matching-6, then the grading system would weigh them as follows:

Color 8 x .10 = .80
Shape 7 x .15 = 1.05
Lustre 8 x .25 = 2.00
Nacre 8 x .25 = 2.00
Blemishes 6 x .20 = 1.20
Matching 8 x .05 = .40

Total grade =


Important Notes:

  1. If the lustre is high but the nacre is thin, the final grade should be adjusted lower as these pearls will often look better than they are. After a short period of time, the lustre will diminish due to the lack of nacre thickness.
  2. Conversely, if the nacre is very thick, but the lustre is low, the final grade may need to be adjusted up. This is especially true if grading pearls that have oxidized over time and are showing some wear. Nacre thickness is so important to pricing in Japan that replacement for the thicker nacre strands must be considered.
  3. Remember to consider the size range of the pearls. A 6x61/2 mm strand that is mostly 6mm should cost less than a strand that is mostly 6 .
  4. The final grade is only a guide and you should be willing to adjust when necessary based on experience or other grading factors.

Evaluating Factors

Overtone Color
Body Color
Nacre Thickness
Final Grade
Pile of Pearls

DISCLAIMER: Grading system is from Guide Reference Manual and may not necessarily be used by other jewelers.


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