Tahitian pearls are found only in French Polynesia, and the scarcity of these exotic pearls can be extremely valuable. And for some of you who has been questioning, why some are really expensive and others aren't? 
You probably can find many Tahitian pearls around the world and some of them can be sell really cheap.  However, when it comes about finding the perfect round pearls with the clearest surface, There might not even have 10% of perfects one and theses can  be classified by their shape, Size color and Lusters, depending on which aspect you are looking for, or if you are looking for perfects pearls for your necklace, it may take years to make the perfect one and even for pearl farmer who are harvesting their own pearls may take ages to make the most valuable and rarest necklaces on earth due to the variables , Shape, size, luster quality and color, all Need to be Perfectly and accurately chosen, as even the slightest change in any of these categories will completely change the look and value of your necklace.