Rangiroa is one of the centres of Tahitian black pearl production. Several farms operate in the lagoon near Avatoru, cultivating the Pinctada margaritifera oyster that produces the lustrous dark pearls sold across French Polynesia.
Some farms offer guided tours showing how the pearls are seeded, grown over two or three years, and harvested. The quality variation is enormous — from perfect rounds to baroque shapes in green, grey, and aubergine. Buying direct from a farm cuts out several layers of markup, though it helps to know what you're looking at. Your pension owner will know which farms welcome visitors.