I've taken a look through several of the threads about grading on the forum. However, I don't think my question has been addressed...though my search mojo may have missed it. How much does quality vary within a strand? If one of the reputable sellers that is part of this forum, lists a grade is this the maximum grade or the minimum grade of pearls within the strand? Obviously, pearl sellers vary substantially on grading philosophy (what makes an AA/AAA ect), but is there an industry norm how the seller's subjective classification applies to a strand of variable quality?