Cracked Tahitian Pearls


Well-known member
Jun 22, 2012
Hi all,

A friend of mine who is a jeweller had a client come into her shop, and wanted to get some Tahitian pearls she bought from Greenhills pearl market set into earrings. The pearls she got looked like pearls, felt like pearls (gritty when rubbed against each other or against your teeth), and so they started drilling. The second they drilled the pearl, the nacre cracked! It was less than, but close to 1mm thick, but that was not the only shocking part. The nucleus appears to be a white man-made stone/plastic bead, which didn't hold up to the drilling, and also the reason why it cracked.

Have you guys ever come across this and does anyone know what it is? How did they even make the fake nacre feel like a real pearl?!
They usually crack when there is a sub-par bead inside. They are often very difficult to drill too. The bead that is most often used in those situations is a Tridacna bead.
Hi Jeremy, thanks for that. I googled Tridacna beads, but they don't look like the bead inside this pearl. The one in this pearl looks more stone/plastic like, the bead cracked as well from the drilling. It's white but looks a bit transluscent on the surface, or could it be a polished tridacna bead?
Tridacna beads are polished nuclei made from giant clam shell. The are typically very white and I don't believe they have any of the 'eye' effect you'll see in US FW mussel shell. I believe you can only be certain by lab testing. It's been a long practice (unfortunately) for some producers to use beads from these shells, which should never happen considering the giant clam is CITES protected. One telltale sign that the bead is being used is the hardness of the nucleus. Sometimes when you drill them, it is like hitting a rock. When a pearl breaks or shatters, it's often because of the bead. The nuclei are a lot more prevalent in larger Tahitian pearls than smaller ones too.
I've asked my friend to take a photo of the cracked pearl...the cracked part of the nacre simply fell off, like it was not adhered to the bead at all. given that the nacre was so thin (and I have just been reading an old thread about the giant clam beads), the heat and pressure should not be too much. I saw the photos of the tridacna and bironite shell bead pictures too, they are white and look chalky, unlike this one, shiny and a bit transluscent.

wait for the photo!
I happen to have had Tahiti pearls cracking by concentric circles on drilling, so I no longer drill pearls when I don' know where they come from and how they were beaded...
photo (18).jpg

Hi Jeremy,

here's a photo of the cracked Tahitian pearl a customer brought in to my friend who is a jeweller. Sorry the photo isn't the best (it was just taken with her phone), but you can tell that the bead is shiny and looks like plastic, but I can't be sure if it's plastic as the weight of the pearl was about right. The pearl size was around 13.5mm, and its weight was 3.9 grams.
Incredible, could you shoot the inner part of the cracked bead? thanks
Stoup nucleus

Stoup nucleus


Just one week ago in Tahiti there has been a customs seizure of stoup nucleus, there has been a total of 543kg of seized stoup nucleus see this article

These nucleus are prohibited for use in nucleus grafting firstly because the pearls made with these nucleus cracks upon drilling and secondly the stoup is a protected animal by the washington convention. I won't be surprised if some of these nucleus have been implanted in some pinctada margaritifera, then it produced pearls which were smuggled to the USA, and these near-zero-value pearls finally arrived in a greenhill pearl market. I don't know the reasons why of these stoup nucleus traffics, but the nacre on the pearls produced is real, the nucleus is just not good. When they pass the export test, these pearls go to trash. This is why people should be careful and buy pearls controlled by the government institutions: Maison de la Perle / Service de la Perliculture.
Great question Caitlin- one would assume so, but a quick Google search is just pulling up lots of Soup recipes for me lol. :)
Wow...that is a lot of lousy nucleus that was seized there. I couldn't find out what "stoup" translate gave me holy water! sorry I haven't managed to post another photo of the cracked pearl, I've not seen my friend for some time, will catch up with her soon enough.
Looks like normal MOP nucleus bead to me. But there are instances -specially with larger beads- that the nacre in the bead will separate (probably a composite bead, not really a solid one) in "layers". Maybe you can apply a drop of acid (or vinegar at least) on the bead and see if it fizzles??? This can help you identify -to an extent- if the material is calcium carbonate.
BTW: I also tried searching for "Stoup" and found the same reference of a "Holy receptacle". I don't know what to think of this but I'll probably drink down a "Stout" beer to see if things clear up for me and will set some little beads on vinegar just for fun too!
Oh, of course! I have seen many photos of baptismal fonts made from tridacna gigas shell. And upscale bathroom sinks!
Right?! I just smacked my own forehead- Duh. :) I'll remember that forever though- Thanks Dave!
Oh, of course! I have seen many photos of baptismal fonts made from tridacna gigas shell. And upscale bathroom sinks!

We saw a few tridacna gigas shells in shops in Georgioupolis, Crete this past summer.