"We're having a party, everybody's swinging..." goes the familiar tune (we have a special place in our heart for Sam Cooke!) and a necklace like this one are definitely dance-floor worthy.  Those polished black onyx--dotted with faceted black crystal, too--are enough to keep those records playing, and a collection of six vintage lacy lucite flowers (love that pearly yellow!) add to the good times.  A vintage black-jeweled clasp fastens the necklace at 18 inches long.  Now that's a party.