Conch Pearl, Strombus gigas or "Queen Conch", Caribbean Sea. Photo Bonhams.

A conch is one of a number of different species of medium-sized to large saltwater snails and their shells. True conchs are marine gastropod mollusks in the family Strombidae, and the most well known species is the Strombus gigas or "Queen Conch". The pearls they produce are calcareous concretions—that is they are non-nacreous and are made up of calcium carbonate (rather than aragonite which is the composition of nacreous pearls).

Of slightly baroque shape, the color of the present pearl, a true rose pink hue, is seen clearly beneath the porcellaneous luster. Its flame pattern iridescence, which is excellent in its structure, appears to shimmer above its surface. Weighing approximately 4.80 carats and measuring 10.0 x 9.0 x 6.5mm. Estimate US$ 7,500 - 9,500 (€5,400 - 6,900)

Bonhams. GEMS, MINERALS, LAPIDARY WORKS OF ART AND NATURAL HISTORY. Los Angeles, 20 May 2014 10:00 PDT - www.bonhams.com