Delicate necklace with natural black Tahitian (?) pearls of peacock color

Delicate style necklace with natural peacock color pearls. They are of high luster and dark blue / purple color. Look like Tahitian black pearls, but can't say for sure. See closeup pictures for details. 17" around the neck, with 2" extension. The free hanging part is 2" long. In excellent condition.