A natural pearl and diamond necklace. Estimate CHF400,000 – CHF500,000 ($408,250 - $510,313). Photo Christie's Image Ltd 2015

The five strands composed of eighty-nine, eighty-six, eighty-two, seventy-eight and seventy-eight graduated natural pearls, measuring approximately 9.45 to 3.20 mm, to the circular clasp set with old-cut diamonds, 38.0 cm

Accompanied by report no. 78509 dated 16 Feburary 2015 from the SSEF Swiss Gemmological Institute stating that the 413 pearls are natural saltwater pearls 

Christie's. GENEVA MAGNIFICENT JEWELS, 10 November 2015, Geneva