This is my first post on the forum. I have learned a lot by reading previous posts already and thank those who are contibutors.

I recently purchased some loose undrilled chinese fw baroque pearls I have sorted out the overtone and orient features thanks to the wonderful post on this topic. My question is what is it about the culturing process that gives the majority if these pearls a flat back? Some only have a small spot that is flat but out of over a thousand or so pearls only a very few do not have a flat back.

Full round eight way rollers you can have them , give me the character of some nice baroque pearls.

Doug

Dear Doug,

The flat back is a result of the pearl sac being assimilated into the mantle. That happens a lot in mantle tissue nucleation.

Zeide

Hi Ziede,

I'm Paraphrasing here to see if I've got it.
The pearl sac forms around the mantle tissue when it is introduced and that is where the pearl will grow, but the similarity of the mantle tissue and the pearl sac allows some of the pearl sac to be absorbed by the mantle tissue causing a deformity in the pearl sac which would otherwise have take on a curved wall as the pearl grow?

Doug Frey

Hi Doug,

That is just about right. The pearl sac also consists of mantle tissue (either foreign from the donor only, autogeneric from the host only, or chimeric with cells from both host and donor) and forms within the mantle. The mantle as an organ of the mussel has a genetically preprogrammed way of dealing with pearls. The way of dealing with these foreign objects in the mantle is to build up mantle tissue on the softbody side of the mantle and dissolve tissue on the shell side until the foreign object starts growing first into the shell (blister pearl) and then out of the shell (warty outgrowth on the exterior). The mechanism is illustrated in the Strack book. Maybe we can get permission from Ms. Strack to reproduce the pictures here.

Zeide

Hi Zeide,
The flat side of the pearl is the one facing the shell. And "the warty outgrowth on the exterior" is referring to the surface on the flat side of the pearl that has detached from the shell?

Doug

Hi Doug,

The warty outgrowth appears on the outside of the shell when it has grown through. These bumps on the shell were the typical "pearl signs" pearl divers and pearl fishers were looking for on shells in the olden times of pearling. I recommend getting Pearls by Elisabeth Strack for reference if you want to learn more. It is so far the definitive work on pearls.

Zeide

Thanks for the book reference, Zeide. I understand what you are referring to now with the warty growth thing.

So much to learn

Doug