Lot 1165. Rare Non-nacreous Orange Pearl--Melo Pearl, Melo melo volutidae, Saltwaters near Vietnam. Weighing approximately 23.78 carats and measuring 15.0 x 14.0 x 14.0mm. Sold for US$ 13,750 (€10,277). © Bonhams

Relatively unknown in the West, even George Kunz's compendium of 1908, "The Book of The Pearl" had no references to the rare orange pearl offered here. So few have been found, it is no wonder. The Melo melo is the marine snail that produces orange pearls the color of a ripe papaya. The snail generates a pearl-like substance to enclose foreign bodies, or irritants, entering its shell. Both orange and pink pearls (from the conch, Strombus gigas) are "non-nacreous", meaning they do not have a layer of calcium carbonate on their outer surface as white pearls do. Instead, they display a fiery, porcelain-like surface, giving them a unique beauty not possessed by other varieties of pearls. A relative of the conch, theMelo melo volutidae is also a gastropod. It is found in the waters of the picturesque Halong Bay, along the northern coast of Vietnam. Several thousand Melovolutes would have to be harvested for a single pearl to be found particularly of the size of this one. The present example displays a light papaya color with very good flame pattern. Its porcelain surface as well as its large size make this one of the world's rarest gems, undrilled. 

 Bonhams. Gems, Minerals and Lapidary Works of Art, New York - 23 May 2012