Regarding pearl nucleus material

[Mostawesomecoffee]

Hi, this is my first post. I've been poking around here, and reading a book I bought, and am curious about the substances used as nucleating material for cultivated pearls. It is my understanding that Mississippi River Shell (MRS) is the preferred nuclear starting material, and that other materials such as the shell of Tridaecna gigas and plastic are used as well. I've heard that shell other than MRS often will disintegrate when used as a nucleating material. Why is this? Why doesn't T. gigas shell disintegrate? Why is T. gigas considered inferior for drilling, is it because it's so much harder than MRS? Is there a general guideline as to what can be used and what can't? It seems that if plastic can be used, most anything should be an option.

 

[GemGeek]

Tridacna gigas is a protected species and the shell is not good for drilling, but doesn't disintegrate. Disintegration probably happens in the creation of the bead in inferior shell. They cut cubes out first and grind them into rounds. Not all shell lays down in tight layers of nacre. If there are loose layers it can fall apart.

 

[Caitlin]

I think you are right about anything (almost) being an option. Galatea Pearls uses turquoise and other gems for his nuclei. He then carves beautiful patterns into the nacre around the nucleus revealing the gem within. And once in a while an invading organism like a tiny fish, worm, or crab will be encased in nacre .. so I guess nacre is an equal opportunity distributor.

For a google page of images of his treasures go here

Tridacna gigas nuclei are brittle and can overheat when drilled, so even though some silly pearl farmers think they are cheaper or larger, this kind of nucleus bites you in the butt and waste your money when you try to drill pearls grown around nuclei made from them- you waste a lot of them through breakage, so it is only cheap for the farmer the first time he tries it. Who would buy from him a second time? Not to mention, Tridacna gigas are enormous, beautiful, and very slow growing, so the big ones are getting more rare due to greed, such as in trying to find a pearl bigger than the Pearl of Allah in one. This is a mistaken quest because no one has ever made a penny buying or selling the PoA in spite of the publicity that it is worth 63,000,000 clams. That is one of the biggest cons ever attempted and if you new readers do not know the story- read it here as a Pearl-Guide.com exclusive expose

Locals are allowed to eat them still, and the smaller gigas are probably better to eat anyway--but I would love to see the world united in scorning the killing of the largest ones for any reason.

 

[GemGeek]

Great post, Caitlin!

 

[Lagoon Island Pearls]

Every shell borne of mollusks contains a matrix of calcium carbonate and protein. The ratio can vary widely between orders.

In bivalves, this can be broken down into three basic groups. (there are more, but for this discussion) Mytilid, Veneroida and Pterioda. Mussel, clam and pearl oyster.

Any pearl farmer will tell you, the best growth is juvenile growth. Juvenile growth is marked with high percentages of protein while mature growth is marked with high percentages of calcite.

Here's a few examples from samples I've measured.


Species Periostracial Prismatic Nacreous Calcareous Other

T. gigas (clam) 2% 40% 5% 46% 7%
M. galloprovincialis (mussel) 44% 20% 18% 12% 6%
P. maxima (pearl oyster) 22% 26% 32% 15% 5%

US river mussels originate in temperate waters, therefore hibernate annually. This gives rise to successive layers of juvenile growth each and every consecutive year. This accounts for thick, workable shells of a material nearly identical to the mineral properties of pearl shell stocks. Tridacna gigas on the other hand, do not hibernate, but become highly prismatic/calcareous within a few years.

I've mentioned before, from a mollusk's standpoint, growing a pearl or building shell is not all give. There is a degree of take too. All living things need calcium. During times of scant food or low salinity, mollusks are able to uptake calcium from their own shells (and yes pearls). It seems abundantly clear to me, an ideal nucleus should be made from a material that is systemically compatible.

Sure, glass, porcelain, opals etc. have been successfully grafted. Like the exquisite Galatea Pearls that Catlin posted and souffl?s stuffed with mud, plastic mabes etc., but I'm also certain the percentages of success are lower overall as the production costs are higher whilst only supplying a niche market.

US river mussels are in good supply, reasonably priced and moreover are ideally suited for high quality, high recovery pearl production.

Even if an artificial bead was created from identical materials in identical proportions to mollusk structures, I doubt a machine could form the aggregate with better precision and strength than a mussel itself.

 

[Pearling Technologies]

Great post Dave. Sure almost anything's possible but there are more factors to consider than just what nacre will encompass. We've seen some weird and wonderful materials when we've recycled nuclei and i don't doubt there are many other materials we don't see. As for mussel, Dave's correct. Stocks are pretty good at present and combined with the use of some MOP shells, supply is not really too much of an issue, especially for smaller sizes. Although when you start getting to the real big sizes, there maybe some supply versus cost factors.

 

[Marianne]

Thank you David and Mother Nature!

 

[Mostawesomecoffee]

Thanks to all of you for the replies.

 

[Cees]

I am a bit disappointed with Caitlin's reply about using the CITES protected Tridnaca Giga's as food or its shell. Can remember snorkling at Puerta Galera in the Phillipines where a number of those Tridnaca's were located, a small boat with a watchman was protecting the shells from being taken away.

 

[Matt_95]

I am a bit disappointed with Caitlin's reply about using the CITES protected Tridnaca Giga's as food or its shell. Can remember snorkling at Puerta Galera in the Phillipines where a number of those Tridnaca's were located, a small boat with a watchman was protecting the shells from being taken away.

It isn't like that in all parts of the Tridacna species range. They're abundant in some areas and used as food. They're also cultured for food and the aquarium trade.

 

[Caitlin]

Thanks Matt. I should have clarified my statement a bit, but as Matt said, some kinds of tridacna are OK for locals to eat. I got the impression that sometimes the smaller, younger gigas are eaten, by locals in some areas- that may be incorrect as I don't remember exactly what my source was. I think the big ones are still being exploited occasionally- maybe with local help sometimes, but such illegal activities are often hard to determine as to who is doing them.

Like how did the recent giant gigas pearls come forth? Someone was taking the large guys and looking for giant pearls. Then when they find one, they come over here or to Kari's Pearls.com and try to sell them. And no one (not even me, so far) asks how and when they were obtained.

So the sooner EVERYONE realizes those giant ugly pearls are worth NOTHING except as local attractions of great attractive quality- like the giant (protected)saguaro cactus forests around Tucson, the sooner people will quit eying the giant specimens with $$$$ in their eyes, if they should kill one and look for a pearl.

 

[Matt_95]

I believe you're right about the younger T. gigas being eaten. T. maxima and T. squamosa are also eaten as well. They actually do grow fairly quickly when they're smaller. CITES only really comes into play when you're trying to move protected animals across borders. If there are no other locks laws applying to the clams they can be eaten and harvested as long as the clams do not cross borders.

 

[Taz]

I think you are right about anything (almost) being an option. Galatea Pearls uses turquoise and other gems for his nuclei. He then carves beautiful patterns into the nacre around the nucleus revealing the gem within. And once in a while an invading organism like a tiny fish, worm, or crab will be encased in nacre .. so I guess nacre is an equal opportunity distributor.
View attachment 29823
For a google page of images of his treasures go here

Tridacna gigas nuclei are brittle and can overheat when drilled, so even though some silly pearl farmers think they are cheaper or larger, this kind of nucleus bites you in the butt and waste your money when you try to drill pearls grown around nuclei made from them- you waste a lot of them through breakage, so it is only cheap for the farmer the first time he tries it. Who would buy from him a second time? Not to mention, Tridacna gigas are enormous, beautiful, and very slow growing, so the big ones are getting more rare due to greed, such as in trying to find a pearl bigger than the Pearl of Allah in one. This is a mistaken quest because no one has ever made a penny buying or selling the PoA in spite of the publicity that it is worth 63,000,000 clams. That is one of the biggest cons ever attempted and if you new readers do not know the story- read it here as a Pearl-Guide.com exclusive expose

Locals are allowed to eat them still, and the smaller gigas are probably better to eat anyway--but I would love to see the world united in scorning the killing of the largest ones for any reason.
View attachment 29824
View attachment 29825

Someone in Australia has been implanting Opal for some time as well with interesting results.