[perlas]

Hi All,

I compared several freshwater white pearls with different qualities under intense light source.

1) In fine pearls (lustrous and with orient)
The pearls are more translucent upon candling. Same as Richard's observation, the pearl appears monochromatic with pink glow.

Do we see the monochromatic color because the pearls are highly translucent and thus, we can actually see the conchiolin since the pearl had undergone little or no treatment?

2) In commercially available pearls (lustrous, no orient, but with bleach marks upon close inspection)
The pearls appear "grainy" or with "spots" (Under normal light, the pearls are round with no pits). It is less monochromatic and I saw a green glow rather than pink.

Is this because the pearls had undergone so much bleaching that the conchiolin is lighter therefore appear to be not visible?

3) Low-grade pearls (not lustrous at all)
Appears milky upon candling, can't see anything but milky white.

I also observed pearls with qualities in between and I think that the finer the pearl, the more translucent it is like a jelly opal instead of the iridescent harlequin opal.

Tell me if my observations are supposed to be what they should be or did I miss something out?

The beauty of not being an expert is I can throw in a lot of questions without being embarassed and Zeide is able to tolerate my most silly questions.

[Zeide Erskine]

Hi Sam,

You are doing just great. Yes that is exactly it. Unbleached high-grade pearls retain their conchiolin and thus appear a tan-tinted translucent color that concentrates towards the core of the pearl while bleached pearls have their conchiolin denaturized and appear to have residual blotches while overbleached pearls have hardly any residual conchiolin to connect the aragonite crystals and the result is a dull murk.

There is one proviso, though and I hope that Richard and Fred will be able to take proper pictures of that. Pearls of perfect water and orient (that means translucent pearls that have not been bleached) do look more like harlequin opals than jelly opals in transmitted light. Actually they look like a slightly yellow mist with an aurora borealis sheet waving inside them. It took me quite awhile to assemble the "teaching strand" I just sent to Richard so it would include every type of translucency and combination thereof, every type of orient and combination thereof, every type of reflectivity and combination thereof, as well as every type of flaw and foul known to pearl world. I even like wearing it, too.

Zeide

[perlas]

Zeide,

I get your drift as I have seen the prismatic phenomenon in other light, naturally colored pearls.

I have YET to see a white pearl that displays the qualities of a harlequin opal. It must be more dramatic. Can't wait for the photographs of the teaching pearls.

[Richard W. Wise]

Zeide,
Will of course return the pearls. Fred Ward has agreed to photograph so, with your permission, I will send them to him after taking a goood long look.

Richard

[Cam Hatch]

This 'teaching strand' sounds absolutely fantastic. A great tool to have for educating your own staff in the business, but also clients that are new to the pearl market.

I wonder how far you could take it....would it be possible to have a strand that features imitation, freshwater, akoya, japanese and chinese, keshi and south sea?? All the same size and colour?

Can't wait to see the images!

[Zeide Erskine]

Hi Cam,

That can be done, yes. It helps to keep a written record of which is which. Chances are, that showing one of those strands to customers might harm your South Sea and akoya sales, though.

Zeide

[Zeide Erskine]

Hi Richard,

Please do forward them to Fred for a photo-op. You may also recruit your wife as a model for distance tests, i.e. let her wear them and observe them at a distance. There is probably little use to compare the teaching strand to how other strands look at a distance because of the size issue. However, if you have comparison strands in similar size, that would be a good idea.

Zeide

[Richard W. Wise]

Hi all,
Well Fred Ward may not join us but he is willing to take a shot at photographing orient. With Zeide's permission I will send the teaching strand along to him.

By the way you may be interested in my new blog post: Burma Journal; The Road To Mandalay. Just the thing for armchair traveling.

[Richard W. Wise]

Ziede,
More on this conchilin thing. The bleaching eats the conchilon? My understanding is that conchilin is a glue like protein binder although some call it calcium carbonate, that is between the aragonite layers. Sort of thought of it as a lasagna, aragonite, conchilin, aragonite but sounds like the binder is everywhere between the crystals.

Why does the lack of it result in "murk"?

Have seen overbleached or Japanese process pearls that appeared to peal.

[Zeide Erskine]

Hi Richard,

All pearls have conchiolin spread throughout and most also have the lasanga layering in addition. When the bleach destroys the conchiolin it destroys the translucent conncetion between the crystals. The murk factor results because the leftover aragonite crystal platelets stick together like salt crystals in a shaker that have become wet and clumped together. If the conchiolin is still present in the original form the aragonite crystals grew on, the crystals touch and light flows through them with less scattering than it would with these conchiolin bridges missing. When the conchiolin accumulates in higher concentration it serves like a mirror backing and when such thicker conchiolin layers are bleached, the resulting short protein fragments are a light mint green and opaque but not reflective. Overall, bleaching always requires additional treatments to remedy its negative side effects.

Zeide

[Richard W. Wise]

Ziede, et al,

Ok, the teaching strand together with two pair of pearls arrived. What I see is the effect that I describe in my book as 'rainbow irridescence' which I distinguish from "true orient" that I then confuse with overtone. Opps, will have to revise that one. Yes it is the same phenomenon as I have observed in baroque Chinese pearls some of which I have on hand.


Examined the pearls under magnification. They have an appearance that differs from the freshadama strands, they have no central shadow and they dont appear pink in transmitted light. If anything the pick up a bit of veining like the green veining in our skin. However, the round ones do have a central shadow and also turn somewhat pinkish so this may be a function of the shape.

From what Ziede is saying, chemical bleaching is responsible for destroying the orient. Great explanation by the way, seems like the source of orient is similar to the source of play of color in opal. Question now is, how do we get to the freshadamas before that happens.

I have to say thanks to Ziede for sending me the pearls. I am not sure that anyone can truly capture this affect on film but we shall try.

Richard

[National Pearl]

Ziede,

Concerning orient within Akoya pearls. I understand that it is very rare for Akoya pearls to exhibit true orient. In your experience, have you seen many Akoya that truly exhibit orient? As was stated earlier, it is not too uncommon for chinese freshwater to exhibit this quality, but I have yet to find Chinese Akoya that exhibit true orient, in my opinion.

[Zeide Erskine]

Dear Andrew,

In order for a pearl plated bead to have orient, it needs to have 30% minimum grown on nacre coating of total mass for a total diameter of around 8mm. Proportionately more for smaller pearl plated beads and somewhat less for bigger ones. That is, of course, the bare minimum to show any orient at all, distinct or strong orient would require more and any orient requires that the pearl plated bead has not been bleached. However, that means that akoya-type pearl plated beads can show orient and I have some both in the bead nucleated variety and the solid-nacre variety. The solid nacre kind is from the fin de sieclé (turn of the 19th to the 20th century) and the bead nucleated kind is from a Korean university research installation using pinctada shimitsuensis.

Zeide

[perlas]

Originally Posted by Zeide Erskine

In order for a pearl plated bead to have orient, it needs to have 30% minimum grown on nacre coating of total mass for a total diameter of around 8mm. Proportionately more for smaller pearl plated beads and somewhat less for bigger ones. That is, of course, the bare minimum to show any orient at all, distinct or strong orient would require more and any orient requires that the pearl plated bead has not been bleached.

Zeide,

In this case, do the akoya pearls maintain the metallic luster and at the same time possess orient or do they start to hold more "water"?

I have seen some loose akoyas with orient and they still appear to be metallic compared to freshwater pearls. But aren't akoyas usually bleached and treated? The akoyas I saw are the half drilled ones intended for earrings. I remember having a hard time matching a 7mm akoya because no other pearl can match the play of colors.

Since the pearl I saw was drilled and had it's bottom cut a bit (enough to expose the bead), I was able to see that the nacre is thick.

[National Pearl]

Thank you Ziede,

I did not know before this thread that bleaching affected the presense of Orient. You are a true pearl wizard!