A Royal natural pearl necklace. A 19th century two-strand natural pearl and diamond necklace. Estimate CHF480,000 – CHF670,000 ($489,900 - $683,819). Photo Christie's Image Ltd 2015

Composed of fifty-five and forty slightly graduated natural pearls, measuring approximately 9.75 to 8.00 mm, to the natural pearl and old-cut diamond cluster detachable clasp, 42.0 cm, mounted in silver and gold

Accompanied by report no. 79345 dated 20 March 2015 from the SSEF Swiss Gemmological Institute stating that the 95 pearls are natural saltwater pearls. 

Provenance: Princess Chantal of Bourbon-Parma
HRH Princess Maria of Savoy (1914-2001)
HM Queen Elena of Italy (1873-1952)
HM Queen Margarita of Italy (1851-1926) 

Queen Elena of Italy wearing the 19th century two-strand natural pearl and diamond necklace.

Queen Margarita of Italy.

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