Conch pearl and diamond necklace, Mikimoto. Estimate HK$200,000 - 400,000 (US$25,600 - 51,200). Photo Tiancheng International

The necklace composed of thirty-five conch pearls measuring approximately 11.46 x 7.10 x 6.74 to 6.90 x 5.02 x 4.10mm, each linked by marquise-shaped and brilliant-cut diamonds together weighing approximately 6.45 carats, mounted in 18 karat yellow gold, signed, length approximately 375mm. 

Tiancheng International. HONG KONG AUTUMN AUCTION, Jewellery and Jadeite