A Belle Epoque enamel and diamond necklace, circa 1910, the circular locket pendant applied with

A Belle Epoque enamel and diamond necklace, circa 1910, the circular locket pendant applied with blue guilloché enamel and set with circular- and rose-cut diamonds, suspended from a sautoir necklace composed of baton-shaped links of blue guilloché and white enamel, spaced by pearls, joined by a circular link set with rose-cut diamonds, mounted in gold and platinum, necklace length 58cm, pendant length 3.9cm including bail, pearls untested, case stamped Birks