Curator reveals fascinating facts about pearls

[effisk]

PEARLS come in all colours, shapes and sizes, and range from black to golden to the palest pink. And, contrary to popular belief, they are not formed by a grain of sand getting inside an oyster.

Full article.

A good change from the ubiquitous "pearls are formed when a grain of sand..." on the internet.

Mike, I suppose you'll have to go to Doha if hou want to see the nautilus pearl firsthand.

I have a few of the photos H. Bari showed at his speech. There are some very unusual pearls. Will post them later.

 

[Valeria101]

The following report from GIA Thailand fits pretty well in the context. Esp. take a look at their list of rare pearl-making species (short list; they must be missing a few! )

Not surprisingly, their most prominent statement:

"Identifying rare pearls [is] work in progress"


CLICK HERE



PS.

What a strange shell hinge! like mechanical parts...

 

[Pearl Dreams]

Worms I knew about, but stingray excrement? That's a new one on me!

 

[Ashley]

All kinds of flotsam floating around can be the catalyst for a pearl- oysters filter feed, so theoretically anything that gets sucked inside the animal and starts irritating the soft body will eventually get coated with nacre unless the oyster can expel it another way...

Valeria, that really is quite an unusual hinge! Wow...

 

[Caitlin]

That article was better than most.

Pearls are formed when tiny worms bore into the shell of the oyster, and the irritation causes the shellfish to excrete a liquid which hardens into pearl. Worms and even small fish are occasionally found inside oyster shells, entombed in a shining pearl casing.

But I think Strack's definition of how a pearl is formed is the best yet. pp 114, & 116-117.

She gives credit to Friederich Alverdes who in 1912-13 discovered the following:
Pearls are formed by the intrusion of epithelial cells into the mantle. The cause of that intrusion may be anything from a fish biting the mantle, thus carrying epithelial cells into the mantle to worms carrying epithelial cells into the mantle. In short, anything that puts epithelial cells into the mantle will form a pearl sack.

Strack has some fantastic drawings that demonstrate the process. When you look at them, you will never have a problem remembering this process.

The pearl curator from Dubai needs a copy of Strack!

 

[effisk]

He does own a copy actually. He's even discussed this very topic with Strack in October last year, and here's what he wrote in an article about a year ago:

Ainsi donc, la perle ne se forme pas autour d?un intrus, ou alors, c?est parce que cet intrus a emport?, en p?n?trant dans la coquille, quelques cellules ?pith?liales. La perle r?sulte d?un transfert de cellules ?pith?liales, migration cellulaire pour laquelle un intrus n?est pas n?cessaire.

Basically the same thing as Strack's definition.

 

[jshepherd]

We can't talk about Hubert without mentioning his amazing book, The Pink Pearl.

 

[Caitlin]

The Pink Pearl is available from a range of book places- most around $40.00. It is apparent the Dr Hubert Bari is a reknowned expert.

So Dr Bari knows, but in the recent article, he does not explain it as he did in the French article. Instead, saying that

Pearls are formed when tiny worms bore into the shell of the oyster, and the irritation causes the shellfish to excrete a liquid which hardens into pearl.

I don't think the average person would get that "liquid hardening into a pearl" line (maybe it is the reporter);it sounds a lot like "the drops of dew" theory......
epithelial cells are a kind of liquid?

 

[jshepherd]

I don't think the average person would get that "liquid hardening into a pearl" line (maybe it is the reporter);it sounds a lot like "the drops of dew" theory......
epithelial cells are a kind of liquid?

He is probably referring to the calcium carbonate excreted by the epithelial cells. I believe the encystation is secreted as a liquid and quickly hardens.

 

[Ashley]

In any case, I do agree with Caitlin about the clarity of the statement; while it's true that not many average retail consumers will be reading in-depth articles written by experts, it is still important to convey the process of encystation clearly... Just my 2c

 

[effisk]

okay, photos!

Strombus

Spondylus regius

Pleuropoca trapezium

Melo

Iopha cristagalli

Lambis truncata

Fusinus undatus

All photos are (c) Hubert Bari.

 

[effisk]

I thought I had one of Cassis madagascariensis but can't find it right now.

 

[pattye]

Effisk,

Thank you! Wonderful photos! Makes me want to reach out and pick up the shells, somehow more intriguing than the pearl--------at least in these photos!

 

[Caitlin]

Thanks for posting those- a very educational thread! Can you add a pic of the nautilus pearl?

 

[effisk]

Thanks for posting those- a very educational thread! Can you add a pic of the nautilus pearl?

hehe I wish I had a better one than the one I posted in the nautilus pearl thread!

 

[Caitlin]

This is a good place to put a duplicate photo with a link to the Nautilus thread. If someone posts such a pearl again, we can add that too.

 

[Miriam Reed]

Effisk,
Thanks for posting the excellent photos. They're very clear and are a good addition to the thread. Don't you wish you had a collection like that? I'm afraid I had to slow down and drag my limited French out of the recesses of my memory to read your quote, but I finally figured it out! As you say, he basically said the same thing as Strack. I remember thinking the first time I saw the diagrams in her book that they show the process in a very clear, easy to understand way. It was a good idea to reproduce them here.

 

[Mikeyy]

Kidney stones are pearls if you want to get technical....LOL

 

[Raisondetre]

Eww!!! Why did you have to say that?

 

[Valeria101]

Yuck, man....

besides, those don't call for epitelial cell seeds (comparing with the Strack drwings posted above) and it is quite debatable whether they have any protective function similar to that of pearls for mollusks.

Sorry for the gratuitous defense.... I just hope there's no comparison (wishful thinking, maybe...). Although, I can think of a couple things tht the mamal body does tat resemble the function of parls (i.e. protective coatings triggered by intrusions in some types of tissue - not usually mineralized though).

That aside...

The white pearl in these piectures reminds another, magnified, posted as a teaser HERE Do you have thee pictrues in larger format, 'effisk' ?