I hope this hasn't been posted yet. I just received this from G&G at GIA.
?Souffl?? Freshwater
Cultured Pearls
Jack Lynch (Sea Hunt Pearls, San Francisco) had an attractive new product he sold as ?Souffl? pearls? at the Tucson gem shows in February. They were large, had high luster, and appeared in a wide range of reportedly natural colors. According to Mr. Lynch, they debuted at the September 2009 Hong Kong Jewellery and Gem Fair as ?hollow keshi.? From their relatively light heft, the dealer probably assumed they were hollow.
Mr. Lynch gave us some undrilled and sliced samples for examination. They ranged from 17.7 to 18.6 mm in maximum dimension, and were white, light orangy pink, and light pink; all were baroque shaped. Microradiography revealed large irregular areas of a relatively uniform gray color in their interiors -- that is, areas more translucent to X-rays than the surrounding nacre -- along with smaller darker, more X-ray transparent areas.
When one of the samples was cut in half, a dark, viscous liquid present quickly dried into the gray matter that filled the pearl?s interior. The mortar-like gray material was completely separate from the outer layers of the pearl, and chemical analysis showed it contained mostly silicon and aluminum -- proving it was not a calcium carbonate or organic material connected to pearls or mollusks.
Mr. Lynch?s supplier subsequently informed him that ?muck,? possibly pond mud, had been used to initiate pearl growth. Since this material was deliberately placed within existing pearl sacs in the host mollusks, the resulting cultured pearls cannot be classified as ?keshi.?
The ?nuclei? are unstable to drilling and may not be present in the drilled cultured pearls, which would explain why the strands have a relatively low heft.
- Nick Sturman
GIA Laboratory, Bangkok
- Elisabeth Strack
Gemmologisches Institut Hamburg, Germany