An early 20th century diamond and natural pearl-set brooch pendant

An early 20th century diamond and natural pearl-set brooch pendant, the four outer pearls each millegrain-set within a surround of circular-cut diamonds and suspending a further pearl with four diamonds to the inner diamond lattice, set in platinum and gold, detachable brooch fitting and pendant loop, 4cm wide

The pearls are natural saltwater as per verbal report from GCS, London.