Shell Pearl

Shell pearls are manufactured. Beads are fashioned from mollusk shell and then coated with artificial materials chosen to imitate many kinds of natural and cultured pearls, such as Tahitian black and white or golden South Sea pearls. GIA analyses found beads made of saltwater shell, in some cases most likely from giant clams (Tridacna), which are protected under CITES Appendix II; GIA has urged manufacturers to stop using Tridacna shell for this purpose.

Shell pearls can match cultured pearls in appearance and heft, so look closely. Under magnification the surface shows a glittery coating with minute sparkling particles instead of the overlapping nacre platelets of a nacreous pearl, and the orient can look multicolored but oily. Near drill holes the very thin coating often chips or peels, exposing white shell underneath. In laboratory tests, X-radiography shows only the inner shell bead (sometimes with parallel banding), and the coating has contained bismuth, which does not normally occur in pearls.

The pearly look is only a thin surface coating. GIA removed it from one sample simply by immersing it in acetone, and observed chipping and peeling near drill holes, so keep shell pearls away from solvents such as acetone and from hard or abrasive objects, and store them wrapped in soft material in a dry place.