It's generally accepted that Akoya pearls, the classic cultured pearls of Japan, are the most lustrous of all pearls. But "lustre" is only one of the 5 quality factors used in judging cultured pearls, the others being "surface," "shape," "color" and "size." Let's review these quality factors, and see how each applies to Akoya pearls. A bit later, we'll do the same with South Sea pearls and Tahitian pearls.