What's going on with these WSS?

[StarryPearl]

I have inserted some photos. My guess is you are seeing an effect similar to the nacre substructure, see the example on the right.
I have seen it in some of my blue japanese baroque akoya too. I will try to post some photos of that too.

I appreciate it, Joaz! Always LOVE to see scientific explanations that drill down the causes. I will search for the whole article and have a read.

 

[StarryPearl]

My pleasure StarryPearl...and we are a community here...people hailing from all over and with different backgrounds but sharing a common LOVE for this special Gem.

And I agree with you on sending them back. With anything you invest in (I mean a hot-dog bun may be a purchase, but never an investment...jewelry purchases are an investment, not just a purchase) YOU SHOULD FEEL AT LEAST 95% SATISFIED. Anything else and you will continuously have this annoying little voice following you and telling you how you kept that piece that you don't like, that makes you anxious, just kvetching all day long

And great to find another fellow Biologist!

Considering buying pearls as an investment is such a good idea. You have successfully relieved my recent sense of guilt and gave me a good reason to buy more! I agree on the feeling you said, that's why I would rather throwing $42 shipping in water than keeping the piece.

 

[pattye]

Thank you for this info, Joaz.

Gorgeous Cortez pearl; each one is special!

 

[Joaz]

The paper is here. I think photo sections b) and d) are in an area of mottling.

Evaluating and identifying pearls and their nuclei by using optical coherence tomography
https://www.researchgate.net/public..._nuclei_by_using_optical_coherence_tomography

 

[CortezPearls]

Great article Joaz...and I see the main use would be to identify a nucleus and this would be crucial for some pearls that are said to have a "giant clam" nucleus inside or those pearls -years ago- that were said to be natural pearls, yet they were cultured pearls that had been seeded with a natural pen-shell pearl.
My friend Stefanos Karampelas did not know any articles about mottling. Trying to convince him to produce one for the world to see!

 

[Katbran]

Douglas - do you know what causes the Blue Akoya to often have a mottled surface? It appears on a lot of the Blues I've seen and there is a pale beige sort of under colour ? And do they actually know why they are blue ? Is it due to a bacterial infection or such creating debris in the layers ?

 

[Joaz]

Great article Joaz...and I see the main use would be to identify a nucleus and this would be crucial for some pearls that are said to have a "giant clam" nucleus inside or those pearls -years ago- that were said to be natural pearls, yet they were cultured pearls that had been seeded with a natural pen-shell pearl.
My friend Stefanos Karampelas did not know any articles about mottling. Trying to convince him to produce one for the world to see!

Yes. the xray technique it was used to identify the nucleus. I found it also very interesting.

It would be very interesting if your friend would study mottling . I am very curios so I would be interested.

 

[Joaz]

Douglas - do you know what causes the Blue Akoya to often have a mottled surface? It appears on a lot of the Blues I've seen and there is a pale beige sort of under colour ? And do they actually know why they are blue ? Is it due to a bacterial infection or such creating debris in the layers ?

I also recently read that Mikimoto is marketing it's blue mottled akoyas "Skilled Mikimoto artisans use a special technique to carefully apply multiple layers in creating the colorful mottled effect.". So my best guess is that others growers are fallowing that trend.

I do like very much blue akoyas (they are my personal favorites) and I have seen that mix of colours too. Blue akoyas, to my knowledge, are most often due to an error in grafting technique... but I think this is not all the story. I am sure they use other thing as well, for example selection breeding of oysters that can lead to intentional or non-intentional alteration of end-resulting pearls.
Another interesting article https://www.nature.com/articles/s41598-017-02457-x

 

[pattye]

We have a misunderstanding here. Mikimoto created a special CLASP with mottled blue enamel work on the clasp, not on the pearls themselves. Here is the quote in context: HERE

I have some mediocre quality blue akoyas. Many have a beigy side because the nacre is thinner there. If a strand of these were rolled on a flat surface these pearls would show "blinking." White akoyas show this effect also.

 

[pearlescence]

I talked with pearl farmers when I was working on a farm in Vietnam about this. They simply don't know. Or why the dark blue is increasingly rare and the only blues are really a silver grey with blue waved at it.
Same with the GIA's pearl expert. They all have suspicions but no solid facts.

 

[pearlescence]

[ have a "giant clam" nucleus inside or those pearls Anyone trying to drill a pearl with a tridnaca nucleus doesn't need an x-ray. Just a whole packet of drill bits.

 

[CortezPearls]

Douglas - do you know what causes the Blue Akoya to often have a mottled surface? It appears on a lot of the Blues I've seen and there is a pale beige sort of under colour ? And do they actually know why they are blue ? Is it due to a bacterial infection or such creating debris in the layers ?

I believe that many Blue Akoya pearls have a thicker nacre coating (above the 0.5 mm norm) and can thus express mottling. The #1 requisite for mottling seems to be thick nacre.
My first experimental cultured pearls were thin-nacred: we needed to check for pearl production results (not for beauty nor quality) at the very beginning, and we obtained many light colored pearls, baroque shaped and BLUE, always underneath the blue we would find a major protein deposit, usually a rotten piece of mantle tissue.
I used to associate blue with this organic deposit. It tended to disappear when I used mercurochrome solution on the mantle tissue/grafts...so no infection=no blue!

Now, true-blues are not the same as the blue of thin-coated pearls. I will look for one of those old reject pearls...I kept a stash of those for inspection. Most are at the farm, so I may not have access to these anymore. If I find one I will take photos and let's see if we can all pour in and find a commonality.

 

[Joaz]

We have a misunderstanding here. Mikimoto created a special CLASP with mottled blue enamel work on the clasp, not on the pearls themselves. Here is the quote in context: HERE

I have some mediocre quality blue akoyas. Many have a beigy side because the nacre is thinner there. If a strand of these were rolled on a flat surface these pearls would show "blinking." White akoyas show this effect also.

Thank you for correcting me. You are right.