How are Black Pearls graded for surface quality?
Black Pearls are graded for surface quality (independently of shape and size) using a scale from A to D. An “A Grade” pearl will have minor surface imperfections limited to less than 10% of the total surface; a “B grade”, less than one-third; a “C Grade”, less than two-thirds, and; a “D Grade” more than two-thirds of the Black Pearl’s surface will have such minor imperfections.
