Tahitian Pearls are grown in very large Pinctada margaritifera oysters and with only one pearl per oyster they are usually from 9mm tor 11mm. Pinctada margaritifera, commonly known as the black-lip pearl oyster, is a species of pearl oyster, a saltwater mollusk, a marine bivalve mollusk in the family Pteriidae.

But Tahitians can range in sizes from 8mm to 16mm. Larger Pearls, especially those over 15mm are considered more rare and valuable. The largest Tahitian pearls can reach up to 18mm, but those sizes are extremely rare. 

The price of a 15mm Tahitian Pearl can vary significantly based on factors such as shape, luster surface quality, and color. Wholesale prices in the current market for AAA quality Tahitians are around 1750. to 1800. for a single, unset pearl.