Keshi Pearls


Addison’s article “Keshi Pearls and Soufflé Pearls” requires updating in at least two areas. First, that keshi pearls are always accidental. Second, that they cannot be determined from naturals.

On the first point, this is from CIBJO’s Blue Book -

5.106 Keshi cultured pearl
A trade term that designates a non-beaded cultured pearl (5.139) formed accidentally or intentionally by human intervention in marine pearl oysters such as the Akoya oyster (Pinctada fucata 9.54), Silver/Gold lipped oyster (9.78) (Pinctada maxima 9.60), the Black lipped oyster (Pinctada margaritifera cumingii 9.58) and Pinctada radiata; it is a by-product of the culturing process. The creation results from the formation of a cultured pearl sac either following injury of the mantle rim upon human handling, from a partial piece of the inserted (grafted) mantle tissue(5.114) or the whole inserted piece (5.163) following the rejection of a bead (5.130).See also South-sea Keshi cultured pearl (5.187), Tahitian Keshi cultured pearl(5.196) and Akoya Keshi cultured pearl (5.7). Alternative name; Lagniappe (or Bonus) cultured pearl.

Second, following application of Chinese grafting methods to saltwater mollusks with the intent to culture more symmetrically shaped “Natural” pearls, the gem labs stepped up their technology to include CAT scanning in order to detect the point of tissue nucleation. THIS paper describes the crisis that the labs were able to avert after observing a huge increase in natural certification submittals in the early 2000s,

While relevant statistics are not available, as a result of improved techniques keshi production appears to be more predictable and higher quality than in the past, with an increasing presence in the specialty pearl market.

Pearl Enthusiast

Hello Steve,

Thank you for the information. I will make the necessary additions/edits to the Keshi Pearls article.

IGS Admin


Excellent. In all fairness, the same misinformation can be found in the specialized pearl community and trade, which would have been the source for the article. The definition for the term Keshi has been a moving target in the past.

As a new IGS member signed up just recently to further expand my gem horizons beyond pearls, let me take this opportunity to thank you and everyone here for this incredible resource.


I’m pretty sure this technique was used more broadly that assumed. I can share some photos of zoomorphic pearls produced in consistent, recurrent morphologies that cannot be, statistically speaking, random. They are all “natural” and saltwater by the book, but that’s hard to accept, given the same motifs produced can be seen in broadly in non-pearl mediums.

Thanks Paul. “Zoomorphic” suggests you are referring to the ancient Chinese technique of mabé (shell blister) production, a very early form of mollusk culturing. Whatever pearl-covered shape desired could be created by attaching that shape to
the interior of the shell and waiting. The most popular “critter” was Buddha.


I was not aware that this was a technique practiced in China, I only knew that it has been shown to be viable/possible in Japan, and I have seen examples from somewhere in the Indian ocean (I have a few, purchased in Java, Indonesia, but I am not sure where they are from exactly - maybe not even the Indian Ocean, I’m just guessing.

That is a pretty cool pic though shared, and although I can’t be sure what, if any, is the motif, that one seems more anthropomorphic to me (again, that’s just a guess, it could be random and i’m doing what humans tend to do, find signal in noise where it may not exist).

Here’s an example of the ones I think appear zoomorphic. This is debatable, of course, and it could be that i’m seeing what I want to see, but I have maybe 6 like this and have seen many more, so it does not appear to be random. To me, they look like a birds (ignore the north American stone arrowhead, many of those have bird-head like tips and I took the shot just to compare).

Paul, thanks for your comments and the photos.

A little more background concerning ‘Keshi’ and the techniques in question, just to stay on the same page and on-subject.

Methods were developed by the Chinese in the 1980s and 1990s to produce symmetrically shaped pearls WITHOUT A BEAD from freshwater mussels. As the much larger mussels can accommodate a dozen or more tissue grafts in the same animal, the economics were clear and China came to dominate the pearl market.

Applied to saltwater oysters, the same bead-less technique can only produce a single pearl per mollusk, but provided certification as ‘natural’ by a gem lab its monetary value is comparatively astronomical. For a period of around 10 years, these cultured ‘natural’ saltwater pearls fooled the labs as they looked exactly like natural pearls under X-Ray. Increased volume and uniformity of submissions for certification caused the labs to become suspicious. Microtomography (CAT) was applied to successfully detect human intervention, a technique increasingly viable as more powerful and affordable machines come on line. Left unchecked, this fraud would have greatly impacted the market.

These tissue-nucleated (bead-less) ‘natural’ saltwater pearls were subsequently defined as intentionally-cultured Keshi. Whereas Keshi have long been regarded as an accidental offshoot of the saltwater oyster culturing process, they are now produced by design (as well as by accident) using the improved grafting techniques.

Thanks for the detail, it’s very insightful, I didn’t know any of that. I had read that there was a very old Japanese technique where they would introduce a non-deadly pathogen of some kind (maybe a bacteria or parasite; I’m not sure), through a tiny hole in the shell of the oyster (or clam - ha, shows you how little I know about these, I don’t even know the exact shellfish :-). According to that article (maybe it as a paper, I don’t remember), the pathogen would trigger an immune response such that nacre would form in the area around it to shield it off from spreading and that would lead to the development of the unusual shapes. I am sorry if this is a very non-scientific explanation, I don’t know any more about it than that, but i think that’s the jest of the technique as it was described.

BTW, welcome to the forum, Stephen. I’m pretty new here myself but I’ve leaned a ton and super happy to be part of the community.

Anyhow, I’ll see if I can find the article if you are interested. Thanks again!

Paul, appreciate the welcome. Yes if you find and would be willing to share that material it would be of great interest! Meanwhile, your interest in pearls appears to be the counterpart to my budding interest in stones. You might want to explore the pearl-focused forums out there (easy to find with a search). After all, it would be like a forum devoted to just one stone such as garnet. (Perhaps such exists but I have yet to search!)


Just to note that upon revisiting the article in question, the two issues at hand remain uncorrected: 1) That keshi are necessarily accidental is false—according to CIBJO definition. In fact, they are routinely produced on demand. 2) That keshis are undetectable from naturals is also false, per implementation of MicroCT technology 15 years ago.