THE ADDITIONAL LETTER F APPEARS ONLY WHEN THE PEARLS ARE FRESHWATER PEARLS, NOT AKOYA PEARLS.
Blue Lagoon Pearls & Grading by: Anonymous
BLUE LAGOON are an exclusive pearl jewelry line distributed by MIKIMOTO. Although they represent high quality pearls they do not meet the MIKIMOTO brand control standards.
Examine the surface of your pearls. What does the surface of your pearls look like to you? Are there noticeable imperfections on the surface of the pearls? For example, in The A-D Pearl Grading System, even the most lustrous pearls will be graded D if 60% of the surface is blemished.
If you could grade the pearls yourself, you can then eliminate the possibility that the "F" mark is a grading mark.
Pearls below D grade are considered not acceptable for use in jewelry.
