[Caitlin]

This is the surface of an unidentified type of pearl, which is white with flashes of color, with an easily visible pattern with the naked eye. Would you experts call this a conch based on its pattern?

Thanks,
Tom Stern,MD



Tom, This photo is sized correctly.
C.

[smetzler]

An excuse to retrieve and review 'The Pink Pearl' by Hubert Bari—the most beautiful book in the world of pearls—is welcome. The wide range of conch flame/chatoyance patterns provided would appear to admit the shapes in your UMP (unidentified mystery pearl!).

Are you already in receipt of the green laser pointer for illumination? Lighting seems to have excited an 'atmosphere' around the 'planet', and the shapes appear somewhat iridescent. Any chance an opal got into the mix?

Looking forward to other comments.

P.S. Despite the title awarded for regular posting, I am not an 'expert'!

[jshepherd]

Originally Posted by smetzler

P.S. Despite the title awarded for regular posting, I am not an 'expert'!

I most certainly disagree. After as much time you have spent here you could easily walk circles around the "expert" sales associate at nearly any store!

[DrTKStern]

Nope, my laser hasn't arrived. This was taken with a Nikon D200 in a cloth tent and lights outside the tent. My wife took it. The phenomenon is quite easy to see with the naked eye, but it took work to catch it on film.

It is about 30 carats, perfectly symmetrical, tear-drop, from Celebes Sea.

Tom Stern,MD

[smetzler]

I have the feeling we're building up to something highly unusual and edifying here…

Originally Posted by jshepherd

you could easily walk circles around the "expert" sales associate at nearly any store!

Actually, if the concept of realizing how much one does NOT know is a qualifier (and there are many of us here), then I will accept your compliment!

[Pearl_dreams]

It reminds me of the iridescence of paua.

[GemGeek]

Whatever it is, I like it!

[smetzler]

Doesn't appear that further comment is forthcoming. Any chance to post an image of the entire pearl? The optics on the close-up are enticing.

[Caitlin]

I am not sure this is the place to put this, but until I figure it out-it'll stay here.

Hi, Caitlin

This article appeared in a learned scientific journal yesterday. The mention of pearl structure is in the mid-portion and explains the characteristics of pearls at the level below discussions of conchiolin and aragonite, etc. It seems appropriate for a pearl experts' website, and if you agree, please post.

Tom






Colloidal crystals make better neural networks

By Adam Stevenson | Published: July 28, 2008 - 01:37PM CT
In order to understand the human nervous system, it is essential to understand the growth and structure of three-dimensional neural networks. However, most neural network studies have been limited to two dimensions or unrealistic representations in three dimensions. In a recent Nature Methods article, researchers from University of California Berkeley and Lawrence Berkeley National Lab demonstrate a method for producing three-dimensional neural networks based on templates made with colloidal crystals.
A colloidal crystal is a highly ordered array of particles with diameters between 10 nanometers and 100 micrometers. It has been shown that particle packing and crystal structure in these substances is tightly controlled by particle size, chemistry, and shape. Over the past decade, colloidal crystals have been heavily studied because their unique optical properties allow them to behave as waveguides and may enable optical computing devices. A common example of natural colloidal crystals is a pearl—pearls get their unique appearance from their underlying colloidal crystalline structure.
In this paper, the authors coated colloidal borosilicate spheres with poly(L-liysine) to promote cell adhesion and then attached rat hippocampal neuron cultures to the spheres. The glass spheres were then placed on top of two dimensional neural network samples obtained from embryonic rats. After three weeks of culturing , the result was a three-dimensional neural network with a realistic neuron density. The authors also found that they could influence and guide network formation by incorporating defects such as larger spheres into the colloidal crystal.
To study the networks, the nerve cells were stained with fluorescent photoswitching compounds and imaged with confocal fluorescence microscopy. This resulted in stunningly detailed images of three dimensional neural networks that allowed the authors to selectively stimulate neurons and record neural activity throughout the network. In this way, the researchers were able to determine connectivity between various layers of the colloidal crystal and study how this connectivity is controlled by factors such as chemistry and electrical history.
Given the chemical and morphological flexibility of colloidal crystals, this work should enable a host of future experiments in neural networks that range from studies of network formation and connectivity to neuron-targeting medications. An enhanced understanding of three-dimensional neural networks could also have implications for future computer processor architectures, network protocols, and other information technology applications.
Nature Methods DOI: 10.1038/nmeth1236

[smetzler]

Originally Posted by smetzler

Doesn't appear that further comment is forthcoming. Any chance to post an image of the entire pearl? The optics on the close-up are enticing.

Still hoping for an image!

[DrTKStern]

Hi Friends,

Delay because I was waiting for authentication. SSEF in Basel, Switzerland, Professor Hanni in command, returned the pearl today and calls it from a marine gastropod, unworked, porcellaneous with flame pattern. Thus it could be a white melo melo, a white conch, a cassis....but not any bivalve such as Tridacna or scallop, nor any cephalopod like a Nautilus. The most costly color of conch is deep pink, and the most costly melo melo an intense orange, but perfect whites such as this and others I have are also quite valuable.

Using electron microscopy, it can be seen that the flame pattern originates in the way the crystalline stuctures alternate from radial to circumferential orientation.

I find it frustrating that the specific gastropod cannot be identified. I plan to try my own DNA testing at Stanford University in the next few months to see if greater specificity can be achieved. This assumes that inside a pearl, in some of that 3-4% water content, a few pieces of DNA or RNA are floating around. Mybe there is not enough genetic material to test.

Whatever we may learn, by this message I hereby call upon the reference laboratories and pearl scientists to cogitate about beginning their own investigation into using DNA typing, in the hope of opening a new world. Imagine if pearls somehow lead to a major medical advance. What if the human body could learn, via DNA fragments, to put a calcium wall around a malignant tumor and simply strangle it to death?

AAA surface, 24 carats, 18mm

Regards to all,
Tom Stern,MD

[aggiep]

Tom,
Baldamera Olivera has done wonderful research with the conus sea snail. He has isolated out regio specific chemicals that can anthsethize just one eyelid at a time. So we never know what can happen with research with other marine animals.

I would love to see that pearl in a not close up shot.

[smetzler]

Originally Posted by DrTKStern

…from a marine gastropod, unworked, porcellaneous with flame pattern. Thus it could be a white melo melo, a white conch, a cassis....but not any bivalve such as Tridacna or scallop, nor any cephalopod like a Nautilus. The most costly color of conch is deep pink, and the most costly melo melo an intense orange, but perfect whites such as this and others I have are also quite valuable.

It is the combination of flame with iridescence, potentially even more striking on white than a color background, that has me on pins and needles here! Calcareous/nacreous hybrid (Effisk's Nautilus pearls inspired the same question)?

[effisk]

Originally Posted by smetzler

It is the combination of flame with iridescence, potentially even more striking on white than a color background, that has me on pins and needles here! Calcareous/nacreous hybrid (Effisk's Nautilus pearls inspired the same question)?

This is what I thought it was until Tom's last comment.

That reminds me I have to ask for that closeup photo.

What is this inner greenish glow? It this the effect of the lighting?

[smetzler]

Originally Posted by DrTKStern

Nope, my laser hasn't arrived.

I had asked the same question! We really need to see a photo of the whole pearl in natural light.

By the way, any news on closer shots of those nautilus pearls?