A single-row natural pearl necklace. Estimate £15,000 - 20,000 (€21,000 - 27,000). Photo: Bonhams.

The graduated row of 111 natural pearls, measuring from 3.3 to 7.3mm, with a baguette and single-cut diamond marquise-shaped clasp, length 55.0cm

Accompanied by a report from The Gem & Pearl Laboratory stating that the pearls are natural, saltwater. Report number 10828, dated 10 February 2015.

Accompanied by a report from The Precious Stone Laboratory stating that samples of the pearls were tested and found to be natural. Report number 964469, dated 1 October 1999.

Bonhams. FINE JEWELLERY, 22 Apr 2015 14:00 BST - LONDON, NEW BOND STREET