8mm 18K Yellow Gold Round Lightweight Ball Clasp with Jump Rings and Safety Bar, Corrugated Texture. Ball clasps like these are perfect for stringing pearl or bead necklaces, and can be used with thread, cord, or beading wire. This particular clasp has closed jump rings connected to the tongue and the clasp itself. This allows the thread to move more freely, and have less wear and tear at the ends due to fraying.