An early 20th century, old and rose-cut diamond and pearl pendant, designed as a scallop shell

An early 20th century, old and rose-cut diamond and pearl pendant, designed as a scallop shell encasing a pearl with bow surmount, the pearl of creamy hue with pink overtones, diameter of pearl ca. 8.8mms, estimated weight of principal diamond ca.  0.55cts, H-I colour, VS1-2 clarity, total estimated remaining diamond weight ca. 3.50cts, total length (inc bale) ca. 5cm, total weight ca. 15.6gms, accompanied by fitted, period case.