Jesus! Just read this post...it's been over 2 years!!! Think I've gotta pay more attention.
Ok...this is what we've gathered from close inspection of cultured pearls at different degrees of production and from literature.
The first coating on a pearl is usually a dark-protein like substance called conquiolin. This protein is somewhat "plastic" and can stretch. So here is the deal:
The Nucleus-Grafting process has taken place...the tissue has grafted, the "pearl-sac" has formed and now begins the deposition of conquiolin, but some organic matter (usually gonadic tissue) is found inside the pearl sac. This organic material then begins to decay, gas (CO2) is formed as a result of bacterial digestion and this gas makes it possible for the protein to expand (as it would happen if you were inflating a balloon). This process eventually stops, the pearl sac now coats the pearl with nacre.
Final Result...a Gas Giant full of nauseating liquids. The pearls are drilled, the liquid removed and then a cleaning/rinsing of the interior takes place (using salt-water). The bead is usually found loose inside the Gas Pearl...some people prefer to fill up this hollow pearl with resin (as with a Mab?), some don't.
These pearls are very beautiful, with a grainier outside, but must be tested for flaws...some will make the pearls crack.
Hope this answers some questions...will try to produce more examples after this year's (2007) harvest. Hopefully we will have some Beautiful Gas Giants this year.