A natural pearl and diamond pendant brooch. Photo courtesy Bonhams.

the pendant designed as drops, each set with a button pearl measuring 12.50 x 12.25 x 11.79 and 12.75 x 12.43 x 11.30mm., within flexible double frames of old mine-cut diamonds, with rose-cut diamond and millegrain accents, convertible to a brooch; estimated total diamond weight: 4.05 carats; mounted in platinum; length: 3 in. Estimate: US$ 25,000 - 35,000 (€18,000 - 26,000) (£16,000 - 22,000)