Produced from the Pinctada Fucata Martensii oyster, Akoya pearls generally grow to about 6-8cm in size. Cultured pearl techniques, which were developed towards the end of the 19th century, along with the marketing efforts of Kokichi Mikimoto helped bring pearls into the mainstream. There is no industry-recognised standard for grading pearls although the AAA to A scale, with AAA as the highest, is generally the accepted method for grading Akoya pearls.