....Well if you are in New York City you could try Tiffany, they have (or used to have) a wonderful Estate jewellery division. If that doesn't work, you could approach Sotheby or Christie. Both are fine arts auction houses, have specific sales of fine antique and vintage jewellery. They are catalogued sales and attract fine buyers. They also list the sales on their web sites so have buyers from all around the globe.
Christie's is currently the world's largest with sales for the first half of 2012 some $3.5 billion representing the highest total for a corresponding period in company and art market history. http://en.wikipedia.org/wiki/Christie's
These are all premium sellers and sound like the right place for this lovely cultured pearl necklace.
