925 sterling silver necklace with natural black Tahitian pearl

Sterling silver necklace with natural black Tahitian pearl. The pearl has a peacock color and is of high luster. 18" chain, stamped 925. 0.75" pendant (with bail) The pearl is 12 mm x 10 mm x 6 mm. It has a birthmark on one side, as pictured (not too noticeable when being worn). Most of such pearls have it, and such birth marks are just another proof of their authenticity.