Tridacna - Giant Clam Shell Pearl

[Antonio]

Please make some general comment on the pearls from Tridacna. Is it considered rare? Does it fetch good market value? I've attach photos on the pearls for comments.

The ruler will give you an idea of the size. I don't have chance to get it certified from GIA yet as we don't have such service in our country. I might have to try and do that next time I travel overseas. The pearls are from the Pacific. I will let you guess which country and location.

By looking through the forum I don't see any posting on this type of pearl as well or maybe I'm wrong. That's why I'm posting this to hope and get some information. Also to share with people who are interested as well.

Note that my response might be slow but I will check and reply whenever possible.

I want to thank all the people who has contributed to this forum especially a few of those dedicated ones. I'm a new guy and I've learned a lot from the postings. I think people who openly shares their knowledge are the ones who will forever get better and be respected.

Thank you.

 

[knotty panda]

Hello Antonio: Please search for the "Pearl of Allah" and you should find lots of information. I particularly like the banding which appears in your larger pearl. Pearls such as these aren't really considered gem quality, however, they can be of interest to the right collector.

 

[Slraep]

Those look like polished shell and not pearls.

Slraep

 

[KAC]

No I think they are Tridacna pearls, they are supposed to have a porcelain look to them with brownish intermediary sections, which these pearls do have.

As for value, pretty much whatever someone is willing to pay for them.

And how about the Soloman Islands for location?

 

[Josh]

I'm guessing Fiji. We have Tridacnas here in Polynesia but not the giant ones, not anymore anyway.
Not knowing anything about them I would agree with Slraep. It's hard to imagine how concentric nacre depositions could make external bands. That being said, it's equally hard to imagine someone going to the trouble to carve up a block of clam shell and parade it as a pearl.
The fact that they are not nacreous, but instead flat in terms of reflection are going to make them a tough sell in my opinion. The internet is the right place for them though. Good luck.

 

[Valeria101]

I don't know what they are: the bands look suspicious to me too by the same reasoning... not sure how a pearl could come out with stripes because of the mechanics o its making: to get such a round shape the pearl must have been rotating in all directions unobstructed in the mantle sac, yet the stripes would suggest that those points on the pearl were always in contact with the same section of the pearl sac producing the different color. Not saying that this cannot happen - just that it seems counter-intuitive to me now.

Secondly, imitations of non-nacreous pearls are reportedly rife, which makes the nature of these examples questionable [e.g. see GIA report on such fakes of Melo pearls made of... Tridacna shell, what else].

Thirdly... and less relevant, the few credible Tridacna pearls I did see were without bands - looking much like unusually glossy white porcelain. Definitely more lustrous then polished MOP. If any do have some sort of brown spots, I wouldn't know.

What they sell for is anyone's guess - these things are so rarely available and of such specialized interest - mostly collectibles, not jewelry stuff... Expensive collectibles!

Bottom line: I can only imagine that most of those interested in paying something significant for such object will know of exiting fakes and want some reassurance in the form of gemological ID.

 

[Valeria101]

That being said, it's equally hard to imagine someone going to the trouble to carve up a block of clam shell and parade it as a pearl.

Never say never! See the article cited above (LINK again).

How hard could it be to fake some (non-nacreous) pearls most folks have hardly heard of before buying... Exotic fakes of even more exotic pearls!

 

[Caitlin]

There is Tridacna pearl on sale on eBay for less than $100,000. It is been for sale for ages and I seriously doubt it will ever sell for that price or anywhere near it.


However, it is instructive to take a look at the pictures of the pearls compared. The Tridacna is very baroque- it looks like a weird growth- as does the the infamous Pearl of Allah. In neither of them is there any kind of banding.

Do they have a slight pink tinge to them? Could we see the bands close up and see a view of the small one turned sideways?

Meanwhile- compare these, there isn't the faintest resemblance in surface texture, for instance. So I think the one on the right may be highly polished Tridacna nuclei made from Tridacna shells, and called "pearls" or "shell pearls" for their shape. It probably cost a fair amount of money.

I see that the one on the left is not a perfect sphere I'd need to see more sharply focused shots on that one, but it looks a little different that the one on the right. I also don't know if Tridacna nuclei can be polished to such a shine, so my guess is just that a guess.

So first get them certified as Tridacna pearls. In this case a jeweler will not do, I doubt there is a jeweler in the world who has seen Tridacna pearls- mostly because they are too big for jewelry. You need a biologist who is a specialist in invertebrates from a museum or university. If they are indeed recognized as genuine Tridacna pearls, get them to write a letter saying so on their official letterhead.

The GIA can look at them under a microscope and tell if there are aggregations of dye , tool marks, and polish marks--or not. They may also know Tridacna pearls when they see one


You must click on this picture and go to the bottom of the page to see other tridacna pearls owned by this seller.

Aren't tridacnas protected? There would need to be a good provenance on those "pearls", because, if they were recently found, I would think they would be ill gotten- but maybe someone else knows more about that aspect.

__________________
So glad that title that wasn't me is gone! Soon I'll be a lowly beader!

You have been a lowly beader since day one, dear friend.

 

[Caitlin]

For home researchers here is a link to some enormous beads made from Tridacna shell.
It is in China. I think those are undyed bands on them. What do you think?

To see an almost endless page of Tridacna pictures follow this link. They are so beautiful. Just keep scrolling and scrolling to see maybe a thousand incredibly colorful images. Enjoy.

 

[Josh]

Caitlin, that Tridacna pearl looks like a piece of cold lard.

 

[Caitlin]

Here is another Tridacna clam pearl from the eBay site. there are a couple of others too. The picture is a link to the seller's site.

I think it resembles a pickled pig's foot.

 

[Slraep]

Horizontal striation is found in nacre(aragonite-MOP) secreting molluscs and non-nacre(calcite-shell) secreting molluscs. In forming MOP or shell, a mollusc's aragonite or calcite is poured flat as compared to concentrically in a spherical pearl.

T. gigas has no MOP so banding or striation is shell(calcite).

Horizontal banding is also a telltale sign of a faux conch pearl which is actually cut from conch shell.

Slraep

 

[Josh]

Cold lard, pig's feet... ah the romance of Tridacna pearls just sweeps me away.

 

[Valeria101]

The small one in the picture doesn't seem to have the bands, does it? And it isn't all round. Maybe... there is some small hope of that one being a pearl of some sort? What do you guys think?

...the romance of Tridacna pearls just sweeps me away.

All the romance of a natural science museum's back room (smell the formol? see the gnarly stuff in jars? etc.). Ah, the non-nacreous charms!

The picture that started the discussion almost got me hoping that at least some of these pearls might be pleasing by shape if not by much else...

 

[Caitlin]

The irregular shape of the small one makes it a little more likely to be some kind of pearl, it just doesn't look like a tridacna......

 

[jshepherd]

The small one could be a tridacna, but the large one is polished shell. It is not a giant clam pearl.

 

[Caitlin]

It would appear that we agree that the large one is not a pearl of any kind, but a sphere made from a shell. It is so large it is probably tridacna shell.

We still have not determined what the pink tinge is from, pearl or photo- I don't think tridacna shells or pearls have a pink tinge to them.

We really do need some focused pictures of the small one from a couple of different angles, but the surface texture is not anything like genuine tridacna pearls...........

 

[Antonio]

Tridacna - giant Clam Shell Pearl

Tridacna - giant Clam Shell Pearl

Knotty:
I think this forum analysis very professionally on Pearl Of Allah (POA). Anyway, I think it's ugly and is a blister pearl right (meaning it sticks onto the shell). I agree this should be more a collector item rather than for jewellery purpose.

Slrape:
I think it might be polished pearl. It's definately pearl and not shell.

KAC:
Yes, they are from Solomon Islands. I forgot I might have that on my profile. It's one of the very few places left on earth with Tridacna shells.

Valeria:
Some have band patterns and some have white. There's no definate pattern like other shells. I will post more photos later.

Caitlin:
Yes, Tridacna's are protected and considered rare nowadays. Especially big ones. I mean one meter or more in length (I think). The pearl you posted doesn't look too good for me but than the value might be because of rareness of it. Thank you for the web link for China. I find the comments on the pearl interesting as well claiming it takes hundreds of years to form.

jshepherd:
Both are giant clam shell pearl. I will post more pictures because I still have more pearls to post.

Caitlin:
Both are tridacna pearls. I still have even larger ones I have not posted yet. That's why I think we are one of those very few places with such large tridacna still exists. It's a protected species. I have asked the guy who got it for me that he does not kill the shell to take the pearl. He told me he doesn't have to kill it to get the pearl. That's why I agree to pay the pearl and requested some more. If they have to kill the shell to get the pearl, I will definitely not buy the pearl. It takes a lot of years for the shell and pearl to grow to big sizes. He also told me you cannot find the pearl inside if you kill the shell as well. You have to know how to get it while it's still alive in the sea without hurting the shell. If you miss the chance than the shell will take alot of years to grow another pearl. I find it interesting.

Thank you everyone for putting your comments. As mentioned I will post more pictures later. Maybe I should use black background so it show more clear. I will also take photo under sunlight condition outdoor.

 

[Slraep]

Slrape:
I think it might be polished pearl. It's definately pearl and not shell.

Hi Antonio,

Sorry, I think it is definitely polished shell---and probably not even T. gigas shell at that.

No pearl has horizontal banding running through it. And it's plainly visible in the bigger pearl you posted.

Can you explain why you think it is not shell? What is the banding? Slraep is curious to know!!

Slraep

 

[Slraep]

It's a protected species. I have asked the guy who got it for me that he does not kill the shell to take the pearl. He told me he doesn't have to kill it to get the pearl. That's why I agree to pay the pearl and requested some more. If they have to kill the shell to get the pearl, I will definitely not buy the pearl. It takes a lot of years for the shell and pearl to grow to big sizes. He also told me you cannot find the pearl inside if you kill the shell as well. You have to know how to get it while it's still alive in the sea without hurting the shell. If you miss the chance than the shell will take alot of years to grow another pearl. I find it interesting.

I find it more unbelievable than interesting.

The T. gigas being a protected species in most areas where it thrives around the globe, would mean that pearl collecting or fishing, along with any other harassment of the clam is also ILLEGAL. What is your friend's name? He is from the Solomon Islands you say? I'm pretty certain they have signed the CITES agreement.

Slraep