Art Deco platinum filigree necklace with 3.00cts in diamonds

Antique platinum filigree pin/pendant with 3cts in old cut diamonds.  The pendant alone measures 2" x 7/8".  The chain is 14k white gold and measures 15" long.  The bale on the pendant can be folded under so it can be worn as a brooch.  Circa 1920.