A Belle Époque diamond pendant necklace

A Belle Époque diamond pendant necklace, the principal round brilliant cut diamond in a pierced, beaded and millegrain edged drop shaped mount terminating in an articulated pendant with a long navette bar and stylised flame ends set with rose cut diamond highlights, to a fine belcher link back chain and box clasp with safety catch, white on yellow metal, length of pendant centre 2.9cm, length of necklace as worn 44cm, estimated weight of principal diamond approximately 0.20cts