10-13mm Black Cultured Tahitian Pearl Necklace, Gold, Diamond Clasp. 18" Our gorgeous, gleaming, dramatic necklace showcases 10-13mm black Tahitian pearls in what is truly a fashion classic. Necklace features a 14kt white gold ball clasp kissed with sparkling diamond accents. Tahitian or South Sea pearls are unique and may vary. Pearl birthstones are the perfect gift for June birthdays.