I would say it is difficult to describe the pearl quality on
website. Also some pearl association in Japan has been discussing
about grading system for many years.
However we still can not find right answer, because there are many
quality check points as luster, nacre, shape, color, spotted, etc.
Actually I can not say good luster yellow pearl is low grade pearl
as just color. Also high luster pearl which has few spots or
semi-round shape too. So if somebody is looking for really certain
quality and price range, he or she should visit the pearl dealer and
check the quality himself or herself.
I recommend "H.S. Strygler & Co., Inc." in N.Y. which I was working.
They have good experience about pearls.
Regards, Yasu Matsuda
KOBE PRECIOUS PEARL & CO., LTD.