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Tridacna Natural Pearl?

leizl

Member
Joined
Oct 28, 2021
Messages
9
Hi all! My brother found this yesterday from Tridacna shell in Philippines . Measuring 78mm. Is this a real blister natural pearl ? How much would it cost if we gonna sell this?

Thank you all!
 

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jshepherd

Natural Pearl
Joined
Jun 22, 2004
Messages
5,720
Yes, it definitely is a natural blister pearl. It would have to be removed to be set, which would make it a worked blister and the value would drop considerably. What your brother has is a collector's item, so it would be difficult to value.
 

leizl

Member
Joined
Oct 28, 2021
Messages
9
Any suggestion what to do? Where to go? Should we leave the pearl there? Or removed it and send to GIA?
 

Lagoon Island Pearls

Well-known member
Joined
Dec 8, 2009
Messages
1,913
Any suggestion what to do? Where to go? Should we leave the pearl there? Or removed it and send to GIA?

This is a conjoined pearl, not a blister. Blister pearls are given rise by external factors, where this pearl is internal in onset. It was likely a single pearl which irrupted from it's sac, later to become affixed to the shell within the extrapallial space. As Jeremy suggested, a pearl which has been cut from a shell greatly loses value, if not destroyed. A good crafter may do well to hide the cuts beneath the setting to add some value. However, this is not the only issue.

Currently, seven giant clam species are candidate species for listing under the Endangered Species Act. This includes two species in the genus Hippopus (H. hippopus and H. porcellanus) and five species in the genus Tridacna (T. derasa, T. gigas, T. mbalavuana (tevoroa), T. squamosa, and T. squamosina (costata). Uncertified trade in Giant Clam products is prohibited in North America. It is only permitted when it's proven to be reared and harvested in a sustainable manner.

Pearls from giant clams have little or no scientific value, after all they are widely known and largely understood how they form. Some loose pearls from Tridacna sp. present with alluring patterns and are quite collectible, but ethically dubious at the same time. If you were to send it to the GIA in any form, they would return it, untested. Not just because it is from an endangered source, but also because the species is already known and not questioned.

As gemstones, they are low to moderately nacreous, unlike the highly nacreous pearls from traditional oysters and mussels.

I'm sorry to disappoint, but your best action is to do nothing. Keep it as a collectible, a curiosity and conversation piece.
 

leizl

Member
Joined
Oct 28, 2021
Messages
9
This is a conjoined pearl, not a blister. Blister pearls are given rise by external factors, where this pearl is internal in onset. It was likely a single pearl which irrupted from it's sac, later to become affixed to the shell within the extrapallial space. As Jeremy suggested, a pearl which has been cut from a shell greatly loses value, if not destroyed. A good crafter may do well to hide the cuts beneath the setting to add some value. However, this is not the only issue.

Currently, seven giant clam species are candidate species for listing under the Endangered Species Act. This includes two species in the genus Hippopus (H. hippopus and H. porcellanus) and five species in the genus Tridacna (T. derasa, T. gigas, T. mbalavuana (tevoroa), T. squamosa, and T. squamosina (costata). Uncertified trade in Giant Clam products is prohibited in North America. It is only permitted when it's proven to be reared and harvested in a sustainable manner.

Pearls from giant clams have little or no scientific value, after all they are widely known and largely understood how they form. Some loose pearls from Tridacna sp. present with alluring patterns and are quite collectible, but ethically dubious at the same time. If you were to send it to the GIA in any form, they would return it, untested. Not just because it is from an endangered source, but also because the species is already known and not questioned.

As gemstones, they are low to moderately nacreous, unlike the highly nacreous pearls from traditional oysters and mussels.

I'm sorry to disappoint, but your best action is to do nothing. Keep it as a collectible, a curiosity and conversation piece.
Thank you so much!
 

jshepherd

Natural Pearl
Joined
Jun 22, 2004
Messages
5,720
That definition has changed. If a cyst pearl, or a whole pearl breaks free from the pearl sac and attaches itself to the shell, it's a natural blister pearl. It's conjoined, but it is the only true current definition of a natural blister pearl according to CIBJO and GIA.

A natural shell blister, on the other hand, starts on the shell's inner surface and creates a sort of bump in the nacre. Even though we often hear these called natural blister pearls, their current official term is natural shell blister. What Leizl's brother has is a natural blister pearl.

This has been a topic of debate within the CIBJO pearl commission. Some people didn't agree with the shift in definition that to be called a natural blister pearl, the pearl had to start as a whole cyst pearl, break free and attach to the shell. But that's how the commission voted.
 

Lagoon Island Pearls

Well-known member
Joined
Dec 8, 2009
Messages
1,913
A natural shell blister, on the other hand, starts on the shell's inner surface and creates a sort of bump in the nacre.
True, so long as it's radius is greatest at the base and an obtuse angle to the shell. E-cells are really good at resolving acute angles by bridging the shortest possible distance. Something drilling through the shell or a crack, may induce a bump in the same geometry. Shell or sand (including mabe nukes) are always natural shell blister type indeed, particularly when lodged in the extrapallial space. After all, the shell hosts the nucleus and or otherwise damaged accordingly. These are for the most part, external factors, yet proximal to the heart. Burst sacs are internal factors re-attached to the shell, and almost always more distal to the heart. These are major differences, hence ought to be grouped as such.

Had we not seen the image, extrapallial, conjoined and pedunculated. would better describe the OP's pearl over the phone, as it were, because it more or less precludes external factors, (which was my point to the OP), while supporting a burst pearl's internal transition from interpallial to extrapallial (a old single pearl at the nucleus a new pearl affixed to a shell) where a "natural blister pearl" still has ambiguities to onset. Left long enough may have resulted a true blister, but I wouldn't call it that because it never got there. I've not read it, but the commission likely based their opinion on those which had and they'd be correct, but only in those cases.

Fireballs are worth mentioning here. The tails are always formed distal TTH. They're also often stuck to the shell, forming shadow-like ridges. The irrupted pearl could be pedunculated while the ridge is blister type at the same time. Yet they are the not same, instead one type is a result of another. The ridges would not exist if not for the peduncle.

The OP inadvertently presented something really cool in the second picture. The reflected mantle of that pearl is visible, revealing the outer epithelium and supporting fascia. Given it's immediate proximity to the adductor, it likely formed in the vestibular mantle, as opposed to the pallial mantle. The vestibular mantle encircles the adductor and creates the surface which the muscle grows upon (highly nacreous in almost every mollusk), instead of increasingly outward growth. I see this kind of bump in my mussel ops, perhaps 5-8%. However much higher, in Pododesmus oysters. Ana called them muscle pearls and some would think to mean mussel pearls, but no, we had to distinguish to avoid confusion. This is a muscle pearl. Common in Tg too, it seems.

Tridacna gigas are taboo, but it is one of the better specimens I've seen. It ought not be wasted because it's genuine and done. It would look nice presented in a meaningful way. The surface is quite bright, clear and smooth. The pink color is nice. At the very least merits that. Unlike the horrific cut stuff that's haunted us all these years.

leizl

Thanks for sharing it with us.
 
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