Are those good quality akoya?

[p135dfa]

This is the designer's website:

icy akoya pearl, mini bamboo link necklace, in 18k yellow gold, 42 inch

our icy akoya pearl with bamboo link is a stunner! pair it with your bamboo link necklace and favorite pendant. in 18k yellow gold.also available in rose gold, and as a bracelet in yellow gold.

dominiquecohen.com

Closeups of the strand:

My questions is: Are those high quality baroque akoya? With the sticker price, you'd expect good quality but her pieces are all handcrafted in 18K gold so it might be the reason for the price?

 

[jshepherd]

It's difficult to tell from the photos because the color doesn't come through very well. I checked the website, but it says each piece is made to order, so the image is stock. Is this an image of the actual piece you'd be receiving? If so, try to get a good shot of the color.

The blue that you see in baroque akoya is due to a secretion on the nucleus when the grafting incision doesn't heal properly. The secretion is brown and will show through the nacre as silver-blue to blue if thick, and will be more splotchy with beige if the nacre is thin.

With baroques, nacre thickness is really important because they peel easily otherwise.

 

[Lagoon Island Pearls]

The blue that you see in baroque akoya is due to a secretion on the nucleus when the grafting incision doesn't heal properly. The secretion is brown and will show through the nacre as silver-blue to blue if thick, and will be more splotchy with beige if the nacre is thin.

Blue pearls are the result of over mature-tissue (highly calcitic) selected from the donor. The youngest, donor (periostracial) tissue yields the best pearls.

Brown pearls are the result of granular (scar) tissue, where the donor cells have lost their program cell memory post-graft

 

[jshepherd]

Not blue akoya pearls ...

 

[Lagoon Island Pearls]

Not blue akoya pearls ...

Yes, akoya too.

You have stated "due to a secretion on the nucleus when the grafting incision doesn't heal properly" but have not described that secretion, nor the protease and/or it's catalysts. Incomplete or non-union lesions may invariably lead to infection, but inflammation by white cells does not cause pigmentation.

The color of a pearl is dictated by programmed cell behavior in the donor, not the recipient. Incomplete healing may lead to infection, which can affect donor DNA which leads to granulation.

Any pearl farmer will tell you, the younger the tissue the more colorful and finer the pearl will result. This best obtained by sectioning the outside extreme radius of the mantle. Sometimes, grafts are cut too wide, resulting a higher return of blue pearls.

There are 4 phases in a shell/pearl growth, Perisostracial > Prismatic > Nacreous > Calcareous. The best grafts are Periostracial > Prismatic cell age group. Nacreous > Calcareous cell age group result blue pearls, especially in Akoya.

Graft selection criteria:
1- Periostracial > Prismatic
2- Prismatic > Nacreous
3- Nacreous > Calcitic

Japanese technicians are fussy about the breadth of their graft sections, after all akoyas are small oysters compared to SS and Pacific Island shells.

Vietnamese farmers are not so fussy, resulting in higher volumes of blue pearls in harvested lots.

Blue pearls grow in otherwise perfectly formed pearl sacs. Nothing about disease or infections are implicated.

 

[p135dfa]

It's difficult to tell from the photos because the color doesn't come through very well. I checked the website, but it says each piece is made to order, so the image is stock. Is this an image of the actual piece you'd be receiving? If so, try to get a good shot of the color.

The blue that you see in baroque akoya is due to a secretion on the nucleus when the grafting incision doesn't heal properly. The secretion is brown and will show through the nacre as silver-blue to blue if thick, and will be more splotchy with beige if the nacre is thin.

With baroques, nacre thickness is really important because they peel easily otherwise.

I tried to take more pics of the strand I got but the color did not come out right. The first one is closer o true color. It’s actually light gray/blueish, more gray.

 

[jshepherd]

No, not akoya too. What you're describing is not how blue akoya pearls occur.

What I've described comes from Shigeru Akamatsu. It's in his book titled Pearl Book, put out by the Japan Pearl Promotion Society.

This is from page 153:

In addition to pigments, organic matter found in the nacre, or between the nacre and the bead nucleus, also play a role in determining color. This characteristic is sometimes called "grounding color" to distinguish it from body color. The presence of organic matter is said to result from two causes: bleeding in the oyster after the insertion of a bead nucleus, and/or the abnormal metabolic activity of an oyster.

A brown organic substance classified as a blemish is seen blue or gray through the nacre. Some akoya cultured pearls are called "natural blue" (or natural gray). This color, however, does not arise from blue pigments, but is produced by the presence of a brownish blemish.

The term they use for a botched procedure that causes the "bleeding" is mal-nucleus.

Shigeru Akamatsu graduated from Tokyo University of Fisheries in 1966 and was a pearl researcher at Mikimoto until 2010. He was also the general manager of Pearl Research Laboratory in Japan from 1990-1997. Until his retirement last year, he was also the Japanese delegate for the Pearl Commission at CIBJO.

Here is a photo of a smashed blue akoya, showing the dark organic substance. This is what causes the optical effect.

 

[Lagoon Island Pearls]

I understand what "grounding" is. It's normal in almost every pearl. This from conchiolin which is a brown chitinous proteinaceous material that is always revealed in xray or candled views. Color in protein is not consitent in the growth cycles, in fact it's near colorless during waning phase of the cycle. Color pigments are stored in lipid cells during the quiescent phases, then released early during active growth spurts.

The author states specifically "in the nacre or between the nacre" and "bleeding" into the space after the graft. These proteins are not visible at the surface of mature pearls, but occluded by subsequent layers. Calcite is semi-translucent, so it stands to reason some light may pass, but again... that's not color from pigmentation of proteins, but from shifting light instead.

Grafts do bleed during convalescence, but not profusely or permanently lest they don't survive.

You statement is singular and needlessly dismissive of the broader issue. What you've described is an exception, not the rule and I would challenge the paper does not suggest this is the rule in every instance. I'll stand on the assertion the greater majority of blue pearls are not resulted from abnormal metabolic activity, but from the simpler incidence of over-mature graft tissue finding it's way into the process.

Again, the majority of blue pearls come form otherwise healthy pearl sacs. A pearl's quality is only as good as it's grafter.

And again, Vietnamese farmers make no bones about cutting wider grafts to create more blue pearls and they do that almost exclusively with akoyas.

 

[CortezPearls]

I'm going to talk about my personal experience growing pearls for some 30 years. We produced what I used to call "True Blue Pearls" (thickly nacre-coated) that have little in common with these Blue Akoya pearls, but at the very beginning of my research with cultured pearls (these were "experimental pearls" usually between 3-6 months of growing inside an oyster) we got HUGE amounts of "Blue" pearls. I mean, these pearls had thin nacre coverings, usually with white nacre and you could see the bead inside easily.

And the one thing we ALWAYS noticed was: there were brown deposits, sandwiched between the bead and the deposited nacre. Always. We cracked easily over one 100 of these just to make sure we had an explanation.
And all these pearl oysters were TINY (5 cm tall!) because they were VERY YOUNG: we could not wait to have older pearl oysters to operate, it would have meant time lost just waiting. So, we are talking about very young organs too (including the mantle).

Anyway, when we operated the oysters and their gonads were full of gametes, we could SEE the beads/nuclei becoming totally covered in a sticky organic residue (imagine a yoghurt covered bead), we then placed the graft tissue on top and waited...what came out were always these crazy blue pearls and we could always see the reason behind the color: the organic residue that basically deteriorated into this dark-brown protein deposit and that was covered in translucent-white nacre (this nacre color is common with "summer" pearls in the Gulf of California).

So, when I read Tamura's (a great Japanese pearl scientist) work and read about pearl colors: his findings were also in accordance with ours: protein deposits that will cause the blue coloration.

We all know and understand that Nature is absolutely AWESOME and may end up showing us similar results with totally different strategies, but in this particular case for Blue Akoya I have to agree with @jshepherd and Dr Shigeru Akamatsu (whom I had the honor of meeting back in 2017): these particular blue pearls are the result of the "brownish blemish".

 

[jshepherd]

II think there might be some confusion in what is causing the color as well. The nacre of a blue baroque akoya is white. It only optically appears blue when there is that organic layer secreted on the surface of the bead. It is not actually blue. It's just an optical effect.

I'd be happy to smash a white akoya pearl to show you that there is no organic (or conchiolin) layer present. I could also smash a baroque white pearl, and you'll see that anywhere in the white pearl that shows even a slight silver or a slight bluish color will have at least some of this organic layer between the nacre and the bead.

This is what causes blue akoya pearls. It is not the calcareous cell age group.

According to Akamatsu, the colors of Vietnamese akoya pearls occur not because of the mantle tissue, but because akoya pearls grown in Vietnam cannot go through a cold, harsh winter, which creates a "cloudy" colored nacre as he describes it.

 

[jshepherd]

I tried to take more pics of the strand I got but the color did not come out right. The first one is closer o true color. It’s actually light gray/blueish, more gray.

View attachment 465983View attachment 465984View attachment 465985View attachment 465986

The first photo that is truest to color shows adequately thick nacre. When it's thin, that brown material shows through as a sort of silver-beige. These have consistent color and good luster.

 

[Lagoon Island Pearls]

I mean, these pearls had thin nacre coverings, usually with white nacre and you could see the bead inside easily.

And the one thing we ALWAYS noticed was: there were brown deposits, sandwiched between the bead and the deposited nacre. Always. We cracked easily over one 100 of these just to make sure we had an explanation.

This explains something you've observed over a long term, which are undoubtedly astute. However, by your admission these were "thin" layers, which suggest outliers rather than across the spectrum. While some may be thin, a lot of commercial blue akoyas have thicknesses equal or greater than whites. With that, I also agree nature may net similar results from different strategies and that is what we are discussing here.

Gametes are a problem. They have always been a problem. It the main reason for pre-graft conditioning (ie) cold shock. Immature organs certainly present issues with pearl growth, but their blood type and endocrine systems are generally normal, so that would be a physical thing specific to that group. That also doesn't explain blue pearls in otherwise healthy, large adults.

Here's the obvious elephant in the room that cannot be dismissed... surely neither of you are suggesting that any part of the mantle can be used to graft quality pearls? Quite clearly, surface quality and colour of pearls depend on critical graft selection criteria. The long and short of it being, grafts selected the closer to the heart, the more calcite that will appear in pearls, while preferred juvenile tissues were never present in the first place. Good technicians take extraordinary steps to produce good grafts from premium candidates. To suggest miscuts and misaligned swaths doesn't happen is incorrect, because it happens all the time. There is just no way for a technician to select perfect tissue every time, even when working with premium brood stock.

We are discussing two causes, two effects. In fact, each may or may not be the result of the other. The question being, which is predominant?

I know one thing for certain, you cannot dismiss all other likelihoods favoring a single interpretation of one. Pseudoscience as it were.

I don't buy into the climate thing (ie) harsher winters affecting surface quality or color. In fact, environmental factors, including pH and salinity variations have little or nothing to do with colour or moreover... growth rates. A clam is a clam, is a clam irrespective of latitude or temperance. In nature, all creatures and their growth rates are measure by "SATUs" (seasonally acquired thermal units). At the equator, where seasons and days are equal, where at the tropics, daylight shifts and growth rates are accelerated to make up for long periods of quiescence. It takes the same time, to grow the same size... in any ocean on the globe. Japan and China's farms are more north than SS and Pacific Island farms, but their growth rates are alike.

 

[CortezPearls]

I differ on the growth rates. I wish I had not "lost" my Master's Degree Thesis (my personal copy was lent to a research institution and they "lost it". I'm still mad at this), but it was about survival and growth rates and I had this beautiful table with the growth rates of over 10 species of pearl oysters from different locations, all clearly displaying very different growth rates...even of the same species at different latitudes. The same can be said of pearl oysters at the same latitude but in different environments (depth, currents and productivity levels).
Now, I even had different stocking densities and I had different growth rates (and mortalities, of course).

 

[Lagoon Island Pearls]

I'd be happy to smash a white akoya pearl to show you that there is no organic (or conchiolin) layer present.

That's not possible. Nacre is a combination of conchiolin and aragonite. All pearls have conchiolin. None have none. Period.

Or are you merely suggesting visible patches of conchiolin in xray or candled views? They do, especially proximal to the heart. Thick as blue? Perhaps no, but why? That point is being missed, because it's been needlessly dismissed and that's my contention here. Wide gaps and acute angles are major triggers to modifying epithelial behaviour. Mass protein/calcite deposits mitigate this by quickly filling void spaces (base concretion) and rounding sharpened corners (acid deconstruction).

There's a huge difference between clotted and other blood factors present between layers than normal conchiolin layers. Over mature graft tissues have lost some of the DNA that re-orders juvenile growth. Cracks in juvenile shells take 2-3 months to bridge, 6-8 months in mature adults and never in over mature adults, instead plugged with thick proteins and calcite.. similar to the manner Akamatsu has described.

Here's the thing. Is that protein that of the donor or the recipient? I'd suggest the recipient which again.. is supported by Akamatsu, after all an otherwise tiny, perfectly healthy graft is simply not capable of producing that much protein before it's developed within a full blown sac. It's fair to say there are multiple etiological factors, but it still narrows down to over mature tissue having a lack of the ability for producing proteins (and elegantly terminated aragonite crystals) both of which are critical to healthy, fine pearl formation.

We've discussed effects after the fact, but not much about the underlying causes. Which is my point.

 

[Lagoon Island Pearls]

I differ on the growth rates. I wish I had not "lost" my Master's Degree Thesis (my personal copy was lent to a research institution and they "lost it". I'm still mad at this), but it was about survival and growth rates and I had this beautiful table with the growth rates of over 10 species of pearl oysters from different locations, all clearly displaying very different growth rates...even of the same species at different latitudes. The same can be said of pearl oysters at the same latitude but in different environments (depth, currents and productivity levels).
Now, I even had different stocking densities and I had different growth rates (and mortalities, of course).

Of course. Available food and the type of exposure can vary rates, even within the same subareas, but that's not my point. That being growth season of Mytilus c. in Canada is about half of that of Baja California, while the actual growth rate is twice as fast because of longer days and a higher availability of food. Thus annual growth rates and total life span are about the same.

 

[jshepherd]

There is conchiolin, but there is no conchiolin layer, which I have seen as dark deposits - especially in abalone pearls.

Blue akoya occur in two ways. The way I've described and through radiation treatment. The radiation turns the nucleus black (cobalt-60 interacting with the manganese in the freshwater mussel bead), and so it creates the same optical effect - the pearls appear blue.

The secretion on the beads comes from the host, not the donor. This is the cause that creates the effect. Poor saibo selection can result in yellow akoya pearls. In this instance, the nacre is yellow and the cause is the donor selection - dictated by programmed cell behavior in the donor, as you put it. But with blue akoya, there is no correlation.

 

[Lagoon Island Pearls]

There is conchiolin, but there is no conchiolin layer, which I have seen as dark deposits - especially in abalone pearls.

Blue akoya occur in two ways. The way I've described and through radiation treatment. The radiation turns the nucleus black (cobalt-60 interacting with the manganese in the freshwater mussel bead), and so it creates the same optical effect - the pearls appear blue.

The secretion on the beads comes from the host, not the donor. This is the cause that creates the effect. Poor saibo selection can result in yellow akoya pearls. In this instance, the nacre is yellow and the cause is the donor selection - dictated by programmed cell behavior in the donor, as you put it. But with blue akoya, there is no correlation.

Again, incorrect. Each successive monthly growth cycle in mid life mollusks includes a layer of conchiolin, a prismatic layer of calcite lathes and a nacreous layer, albeit microscopic. There are no exceptions, unless the creature is under extreme environmental stress or in winter reversion when a mollusk gets calcium to uptake to soft tissues from it's own structures.

The yellow color is granular tissue. Scar tissue, if you will. It's lost most of it's DNA for rejuvenation and elegance. Instead, the graft remains viable within the vascular supply, but where simplistic grain-like cells formed around the bead and producing only crude calcite. The main reason for this, is the same as the other... inadequate viability of the donor tissue, but for markedly different reasons. There are several cell types that must be present within every graft tissue to be fully viable. Lipid, stem, muscular, fascial, mineralizing to name a few. Even the orientation of inner and outer mantle e-cells matter. Inner mineralize, outer do not. Low numbers of any one of these can yield entirely different results. There are dozens of reasons why tissues are not fully compatible, but it's almost always the quality of the graft itself or the anatomical locale it was selected from.

 

[jshepherd]

I thought your response to the photo I posted was that the dark organic matter was conchiolin, which can present as a dark lines within nacre. If that isn't what you meant, I misunderstood. I do understand the pearl growth process.

My comments about the yellow nacre again comes from Akamatsu's book. If you disagree with him, please share with us where you are getting this information. Can you post a link to a journal article or a book reference?

 

[pearlescence]

I differ on the growth rates. I wish I had not "lost" my Master's Degree Thesis (my personal copy was lent to a research institution and they "lost it". I'm still mad at this), but it was about survival and growth rates and I had this beautiful table with the growth rates of over 10 species of pearl oysters from different locations, all clearly displaying very different growth rates...even of the same species at different latitudes. The same can be said of pearl oysters at the same latitude but in different environments (depth, currents and productivity levels).
Now, I even had different stocking densities and I had different growth rates (and mortalities, of course).

You should be able to get a copy from the institution which awarded the master's. Their library should hold a copy. I don't know if you have access to an inter-library system in Mexico or USA (depending on where you got your master's,) but here in the UK we have access to such materials for a small fee via our local county library too.

 

[Lagoon Island Pearls]

Cultured Pearl Surface Quality Profiling by the Shell Matrix Protein Gene Expression in the Biomineralised Pearl Sac Tissue of Pinctada margaritifera

• August 2018
• Marine Biotechnology 20(1):1-12

DOI:10.1007/s10126-018-9811-y
Authors:
Carole Blay

• French National Institute for Agriculture, Food, and Environment (INRAE)

Nucleated pearls are produced by molluscs of the Pinctada genus through the biomineralisation activity of the pearl sac tissue within the recipient oyster. The pearl sac originates from graft tissue taken from the donor oyster mantle and its functioning is crucial in determining key factors that impact pearl quality surface characteristics. The specific role of related gene regulation during gem biogenesis was unknown, so we analysed the expression profiles of eight genes encoding nacreous (PIF, MSI60, PERL1) or prismatic (SHEM5, PRISM, ASP, SHEM9) shell matrix proteins or both (CALC1) in the pearl sac (N = 211) of Pinctada margaritifera during pearl biogenesis. The pearls and pearl sacs analysed were from a uniform experimental graft with sequential harvests at 3, 6 and 9 months post-grafting. Quality traits of the corresponding pearls were recorded: surface defects, surface deposits and overall quality grade. Results showed that (1) the first 3 months of culture seem crucial for pearl quality surface determination and (2) Multivariate regression tree building clearly identified three genes implicated in pearl surface quality, SHEM9, ASP and PIF. SHEM9 and ASP all the genes (SHEM5, PRISM, ASP, SHEM9) encoding proteins related to calcite layer formation were over-expressed in the pearl sacs that produced low pearl surface quality.re clearly implicated in low pearl quality, whereas PIF was implicated in high quality. Results could be used as biomarkers for genetic improvement of P. margaritifera pearl quality and constitute a novel perspective to understanding the molecular mechanism of pearl formation.

Bolding mine.

SHEM-# aka shell matrix proteins are implicated in the surface qualities of pearls. These are processes which invoke changes in growth types, namely from perio/myostracial > prismatic > nacreous > calcitic. When they are present at the time of graft, they accelerate rapidly, hence over-expression occurs. In nature, SHEMs (particularily SHEM9) is implicated as a senescent trait (9 being the last order of the life cycle) in molluscs It's what induces crude calcite. The shells are old and stong, so the need to continuously create strong nacre, is reduced with age. After all, juvenile tissue has no immediate need to become highly calcitic, instead evolves through a more elegant process thus morphing accordingly over a greater window of time. In nature, nacre is all about strength and water tightness and little else. Alluring iridescence is merely incidental to it.

The only way to avoid early senescent traits in pearls is to not use over mature tissue during the graft, otherwise any part of the mantle would be acceptable to use, but it's not and the primary reason why this is true. There are undoubtedly other reasons, but not greater reasons.

I thought your response to the photo I posted was that the dark organic matter was conchiolin, which can present as a dark lines within nacre. If that isn't what you meant, I misunderstood. I do understand the pearl growth process.

My comments about the yellow nacre again comes from Akamatsu's book. If you disagree with him, please share with us where you are getting this information. Can you post a link to a journal article or a book reference?

Conchiolin can be dark, almost black and opaque. It can also be clear and virtually transparent. Why the difference? For lack of a better description, lets compare it to urine. In the morning, it's dark and odorous, but later in the day it runs much clearer. That's because we rested for a period, then later became more anatomically metabolic over time. The same applies to molluscs. After a period of quiescence, they become more active on the other half of the growth cycle. This is evidenced by lattice patterns seen on shells. Patterns which seem to replicate themselves on subsequent growth cycles.

On the contrary, I agree with Akamatsu's observations on proteins and debris deposited in the sac. Though I admittedly did not read the article, no reference to a root cause for the issue is shown, insomuch as an observation after the fact.

We all know this to be true, but why? We know it's not gametes, because gametes can be controlled by other means. Likewise know which seasons are better to graft and which are better to harvest, so it's not that either. We also know, none of this is spontaneous. DNA and sophisticated cells do not magically appear out of nowhere. They always, exclusively divide and multiply from the annexed space into the into the adjacent, available space. Moreover, it's not careless deftness by grafters otherwise it would be a thing and I've yet to see a paper or farmer that suggests bluing is a direct cause of inept procedures. Flattening and smoothing grafts is a thing though. It's well known, this can break DNA, but that almost always results in granulation, which is a whole other issue. Can flattening/smoothing be the case here? Partially true perhaps, albeit inadvertently. Is it the primary reason? I have misgivings about that. In general, I doubt farmers needlessly tweak grafts for this very reason, much like a chef knows not to flip a pancake too early, lest the whole thing becomes undone.

That doesn't leave much wiggle room for other likelihoods. Jeremy made a good point, a strong one at that. Douglas concurs and so do I, but not to the extent this point is the exclusive or sole reason for the incidence of blue pearls. It's an outlier. The exception, not the rule. A retrospect in the absence onset. This is why perimortem analysis is far more significant than the retrospective analysis of pearls. Once the object is removed from it's situation, the greatest scientific value of it's onset is lost. 99% of my successful periostracial grafts were blue or otherwise highly calcitic, mainly because all of the sectionable mantle in pteriomorphs is over-mature anyway. I'd have to scape the gonoducts to gather new tissue, and that's tricky, if not impossible. Not for any other other reason than a hefty presence of undesirable SHEMs in the soft tissue. I get bright colours, smooth surfaces elegant nacre from the adductoral mantle though. Afterall, it's a highly regenerative organ which lays up the surface for the muscle attachment points. It grows rapidly and very narrow and thin, which really limits productivity when using it as graft tissue.

Again, this supports tissue maturity issues with direct proportion to low quality pearls. Likewise, supports willy nilly selection criteria of the pallial mantle creating inferior pearls remain at the forefront of all other causes.