Is this a real pearl?

[SeafoodJunky]

Bit down on this while enjoying oysters last Saturday. Is it a pearl?

 

[GemGeek]

Yes, but it appears to be non-nacreous, or pearly. You are very lucky to have found one.

 

[GemGeek]

I deleted your duplicates now that you have successfully made a thread. People will find your post more easily in its own thread.

 

[Pearl Dreams]

Very cool! Lucky you!

 

[SeafoodJunky]

Thank you.

 

[SeafoodJunky]

Lucky as in jackpot? I'm kidding. From the little I've just read on non-nacreous pearls, it seems as though they are not worth anything. I will cherish it.

 

[Pearl Dreams]

No jackpot, sorry! Still, it's pretty unusual to find one. So that does make it special.

 

[SeafoodJunky]

It sure does! Thanks!

 

[Lagoon Island Pearls]

If it's from an oyster, it's nacreous.

100% of Class: Bivalvia, are nacreous animals. Bivalvia means two mineralized shells. Likewise, most gastropods are nacreous. Nautilus (cephalopod) are nacreous animals.

Even some annelids (calcareous tube worms) have crude, nacreous linings.

The purpose of nacre is twofold. Shell structure and where soft and hard tissues meet. All hard pearls form in a pearl sac, hence the latter is true in nearly every case.

Technically, non-nacreous means the absence of mineralization by aragonitic layers. Any molluskan shell (or pearl) growth period is marked by periostracial (or sometimes myostracial) ---> prismatic ---> nacreous ---> and sometimes calcitic processes. NO EXCEPTIONS!

The correct usage of the term would be (for example) - A cephalopod or nudibranch are non-nacreous mollusks. After all, they have no shell.

If we were to split hair and suggest "nacreous" is exclusive to structures of terraced or columnar aragonite, then even pearls largely structured in foliated calcite are nacreous to some degree.

The only pearls suspected to be non-nacreous are proteinaceous. Even then, some mineralization may be present, but is NOT integral to it's structure.

I've attached two images of soft proteinaceous pearls because there is little or no aragonite or calcite present. They grow exactly like any other pearl in concentric layers and can be peeled like an onion. If allowed to dry, they shrivel to a mere fraction of their original size. They have a specific gravity only slightly greater than 1.0, whereas hard pearls are upwards of 2.6 to 2.8 ... a huge difference.

I have a few slated for SSEM in the next shipment to the lab this month. This ought to dispel this myth forevermore.

 

[MSC]

Dave, interesting as ever. Are there any publications that exist in the literature about the topic or will yours be the first?

 

[GemGeek]

Dave is right. I meant that it doesn't have an iridescent pearly surface. But it appears to have a nice pattern to the nacre. It does have monetary value - just not big bucks.

 

[BWeaves]

Whoa, that second photo. Looks like the remains on the tray after I've been to the dentist.

Are those peelings? Or shriveled pearls?

 

[Lagoon Island Pearls]

Whoa, that second photo. Looks like the remains on the tray after I've been to the dentist.

Are those peelings? Or shriveled pearls?

Yes they are peelings of a freshly harvested soft pearl.

Dave, interesting as ever. Are there any publications that exist in the literature about the topic or will yours be the first?

No publications that I'm aware of, but we mean to change that because the term is ambiguous if not totally off-base. That's the beauty of science, that things may be falsified in the presence of better evidence.

Sorry to go off-topic SeafoodJunky, but I'm sure you'd be interested in this tangent, if I may for the rest of the group.

The question being, are nacre and nacreous the same thing? In science, nacreous is a step in a process describing terraced aragonite structure in shells. Order: Ostrieoda (oysters), Mytiloida (mussels) and Pterioda (pearl oyster) have nacreous structures following prismatic structuring in the growth cycle, which forms the soft tissue lining. Order: Pectinoida (scallops) (for example) have foliated calcite structures not observed in pearl oysters and mussels, BUT not in the absence of nacreous structures. The adductors are attached directly to terraced aragonite. Nautilus are considered highly nacreous, but are technically columnar aragonite. Their attachments are not permanent like bivalves, but morph to new locations as the animal grows. Sometimes environmental stress interrupt these stages and the classic long blister pearl is formed at the point of attachment with... yep ... terraced aragonite.

I really doubt "non-nacreous" was coined by a scientist. To qualify the term, one must have published a paper supporting the absence of aragonite in a target species. Originally I could have guessed as some species, knowing they were structured in something other than terraced, but having studied foliated calcite (previously presumed to be non-nacreous structure) revealed the presence of terraced aragonite in every case.

I suspect the term was created by the cultured pearl industry to detract from alternative farming techniques with exotic species and proclaiming pearl oysters as superior in structure.

To be correct, the food oyster is nacreous. Lustrous pearls are highly nacreous. It's that simple.

To properly flesh this out, a pearl must be destroyed and examined with electron microscopy. Here's the evidence as shown in the structure of a pearl from Pododesmus machrochisma aka Rock Oyster, Order: Pectinoida. At the left lower corner is the prismatic layer. Next is a layer of clear conchiolin (protein). Moving right, you can clearly see strands of terraced AND columnar aragonite, then right of that is foliated calcite. If you look closely, you can even see thousands of "micro" pearls lining the space between the aragonite and calcite.

The microscopic world is a wonderful place.

 

[Purranha]

Whoa, that second photo. Looks like the remains on the tray after I've been to the dentist.

Are those peelings? Or shriveled pearls?

BWeaves - you are on a dark path today - body parts on Pompeii followed by dentist visit remains. Woof! Lololol!

 

[CathyKeshi]

Mesmerizing information as always, Dave ... much appreciated!

 

[SeafoodJunky]

Wow! Interesting and very much appreciated!

 

[SeafoodJunky]

What would be the value of something like this? Do you think it will make for a nice ring?

 

[MSC]

Check out what someone else did with their found pearl: https://www.pearl-guide.com/forum/s...-a-clam-I-was-eating-The-Quahog-Thread/page14

 

[BWeaves]

Food oysters and clams are not the same types that are used to grow pearls for jewelry.

But, if you think it is pretty, make it into jewelry. If you don't think it's pretty, put it in a box and take it out to tell the story.

 

[Lagoon Island Pearls]

What would be the value of something like this? Do you think it will make for a nice ring?

We don't know the size. We've only seen one image of one side of the pearl.

Even with more information, we're reluctant to appraise value. For both yours and a buyers sake.

I can say with certainty though, it's low gem quality. By no means bad, just not medium or premium.

Personally, I don't view most pearls with a gemological eye. I look upon them as wonders of nature and creation. Like the rings of a tree or the erosion of a stone, they speak volumes to our climate and environment. Some of my most esteemed pearls have little or no gem quality.