Orient color

[SteveM]

?it is iridescent thus having orient.

Coming full circle! The pearls and shell are more than beautiful?they're fantastic. Need to get some?

But for the purposes of clarification, am I to understand that the antique glass bottle in my post #19 has 'orient'?

Steve
Seattle

 

[Valeria101]

But for the purposes of clarification, am I to understand that the antique glass bottle in my post #19 has 'orient'?

I don't know that particular bottle, but couldn't find any better one-word description for iridescence occurring throughout the volume of some material (i.e. NOT a property of the surface layer only). Colorless roman glass comes to mind as a better example. Not that catching that effect in photography of ancient glass is that much easier! The exact image I have in mind (transparent, near colorless glass with iridescence showing with movement) didn't come out from Google Images, this one from the conservation centre in Liverpool comes close:

And these: LINK with physical explanation of the property included

But would rather reserve the term 'orient' for pearls, as it is done already.

There may be other gem materials prized for the spectacular effects of thin layer interference. I am not sure off hand if fire agate, opal, ammonites and feldspars owe their iridescent colors to the same effect. Besides, I expect consistency of the iridescent layers to be part of the 'look' called 'orient' - i.e. iridescence combined with translucency and depth, not a visible sheet as it opal, or from internal fractures in some stones (e.g. 'rainbow' quartz). So that one gets to see the progression from translucency to the iridescence at the right angle uninterrupted, as it happens for pearls and little else. Picky!... I know...

2c

 

[jshepherd]

What a scientific analysis there, Valeria! Thin layer interference is the best description that I know of, also referred to as thin film interference.

But what is important to point out is that not all pearls will exhibit this. Sure, the color expressed in the pearls above is referred to as orient. As are the colors that move around a Tahitian pearl. In the industry, we call it orient. But academically, it is not. Tahitian pearls canNOT have orient according to CIBJO and every gem lab in the world, but according to the industry they can. This is because visually you see the play of colors (the classic soap bubble or oil-slick look).

This could be a big debate that goes on endlessly with every producer emphatically claiming they are right. White South Sea producers claiming South Sea has the best orient, Tahitian producers scoffing at those claims and claiming Tahitians have the best orient, akoya producers claiming the same orient combined with luster, and freshwater producers... etc, etc, etc. I know there is a debate going on behind the scenes even now, with specific segments upset at me for describing the true academic meaning of orient.

Like I said before. Every pearl producing segment in the industry has their own definition of orient, and it best suits their own production. This should not be a big issue. It is the highest value factor in each segment.

May I also suggest just coming out on this thread and debating individual views? What could be better than competing producing segments having an open platform to tell the world why their orient is the right orient.

 

[SteveM]

?would rather reserve the term 'orient' for pearls, as it is done already.

?'orient' - i.e. iridescence combined with translucency and depth?

Superb post! This thread should be a lesson to all forum members not to be afraid to ask dumb questions?with results like that.

I am completely comfortable with the two summary points above by Valeria as a satisfactory use and understanding of the phenomenon.

Steve
Seattle

 

[Casey.R]

I'm editing this too.

 

[jshepherd]

I am pretty sure he was referring to his own question about a bottle having orient, not your original question.

 

[Casey.R]

Oh, I guess I've sort of lost track.
Long thread.

 

[jshepherd]

This thread seems to have stirred up a lot of emotion hidden from public view as well! I really wish those who have such strong opinions would come here and voice them and debate them. The forum is open, fight it out! I am certainly not one to disagree with industry definition and jargon, I am in the industry, and I subscribe to the argument of orient in Tahitians, South Sea, freshwater, and now even akoya. But I still stand behind what I said before.

Does it matter? They are interpreting the same thing differently to suit their own industry, but at the same time using the same definition to describe the rarest and most valuable attribute found in their own production. Either way, to them, it is orient.

I think the complaints are simply backing up my assertion. Every producing segment has a different definition of orient - and it will always suit the particular producing segment that describes it.

 

[SteveM]

Things are moving fast here—I was definitely referring to my question regarding 'orient' in the antique glass bottle.

Steve
Seattle

 

[perlas]

Maybe Jeremy or one of the other pearl vendors on this site will know more about that ( child labor issues). I think I read in a recent article from national geographic that the the legal age in China to hire someone at any type of job was 16.
When you get into the specifics of materials used in jewelry some do have some undesirable elements to them. I mean we all know about diamonds and I hear things aren't always peachy at some platinum mines either. I could go on.... but I won't.
I guess there are things you can do to be extra careful if your concerned.

Rather than child labor issue, culture may have something to do with it. In a lot of Chinese family businesses, sons and daughters are trained very early in the ropes of business. I've seen 7-year-old sons and daughters as cashiers, being trained by their parents. It is thus a plausible assumption that children of pearl farm and factory owners are trained to learn to evaluate pearls at an early age.

As for child labor, a lot of countries can be so poor. Child labor exists in the clothes you wear, in the food you eat and in things more basic. This is the dark reality. This is not restricted to diamonds, or gold, or gems.

But what is important to point out is that not all pearls will exhibit this. Sure, the color expressed in the pearls above is referred to as orient. As are the colors that move around a Tahitian pearl. In the industry, we call it orient. But academically, it is not. Tahitian pearls canNOT have orient according to CIBJO and every gem lab in the world, but according to the industry they can. This is because visually you see the play of colors (the classic soap bubble or oil-slick look).

Why did the CIBJO and every gem lab in the world state that Tahitians cannot have orient? Is it because the tahitians are dark colored thus translucency is very,very rarely seen if at all (since color is only the major factor that separates the tahitians from other commercial pearls)? This is such a bold statement. If tahitians cannot have orient because of their dark color, then this statement would go for all dark colored pearls such as the sea of cortez pearls.

However, as per Valeria's post with the rainbow garnet, I've seen these dark garnets with a thin film of iridescence. They are indeed dark but the iridescence occurs. In some way, can't this be possible to happen to dark colored pearls such as tahitians (especially that translucency may be present in light colored pearls)? The occurence maybe ultra rare but it's difficult to say impossible.

Keep in mind that ‘orient’ is not a factor in commercial pearl grading systems, which focus upon: Luster, size, shape, color.

Besides, I expect consistency of the iridescent layers to be part of the 'look' called 'orient' - i.e. iridescence combined with translucency and depth, not a visible sheet as it opal, or from internal fractures in some stones (e.g. 'rainbow' quartz).

If orient is truly defined as iridescence with translucency, then I'm not baffled that it is not in the commercial grading system. First, a pearl with "water"/translucency is hard to come by. Second, what more if it is with iridescence. This definition of orient if for the gem aficionado to define the boundary of rarity. What are the odds of finding a single pearl with great translucency and iridescence? Thus commercially, it is improbable that it will be in the grading system, as pearls are usually sold by the strand. The really rare gems are not commercial. Even some are sold at a cheaper price than well-known gems. It it just not feasible to market very rare gems if the supply is limited or unstable.

Personally, I'm on the picky side, too.

This thread seems to have stirred up a lot of emotion hidden from public view as well! I really wish those who have such strong opinions would come here and voice them and debate them. The forum is open, fight it out! I am certainly not one to disagree with industry definition and jargon, I am in the industry, and I subscribe to the argument of orient in Tahitians, South Sea, freshwater, and now even akoya. But I still stand behind what I said before.

In the industry, I have to say that orient is defined as the "rainbow" in pearls with no definite relation to translucency. Everyone I think in the commercial pearl industry that I've talked to or encountered has this clear-cut definition. Add "water", i think it will create a stir and a lot misunderstanding. In this definition, tahitian pearls has the advantage due to the peacock colors. Given not every pearl has the play of colors, iridescence without translucency is still very rare.

 

[jshepherd]

Yes, the rainbow of color is a part of it. In dark pearls it is the most important part of it. In Tahitian pearls it is the way the colors move around the pearl as you examine from different angles, with one color holding the center of the rings of "orient". But in white pearls and light pearls, the translucency is most certainly considered a part of orient. This is industry standard as well, and why akoya pearls are not considered to exhibit orient except in rare circumstances - even though they very often have the rainbow of colors on the surface (surface being the key word).

The term water is no longer an industry term. The closest term we have today is orient, which was once directly related to water - translucency is key in the true definition of the word.

But this is what causes the difference between academic definitions and industry. CIBJO would consider, as does Elisabeth Strack, the rainbow of colors on Tahitians (and Sea of Cortez) to be overtones because they do not fit the gemological definition of orient. But to all of us in the industry, this play of color is considered orient.

Take the chocolate pearls for example. Emiko has succeeded in making a clearly defined distinction between dyed chocolate Tahitians and bleached. The original chocolate Tahitians were created by removing color, not adding. The end result of either method is what anyone would consider to be "chocolate Tahitian pearls", but only one would be the true chocolate according to now "established" gemological standards.

So who is right? Those that rely on the science, or those that rely on the industry standards? If we rely on science we no longer say things like "bead nucleated", "freshwater keshi", or "pearl oysters". If we side with the industry, the original meaning of orient changes with the natural evolution of the industry, just as the term keshi has.

 

[SteveM]

Perhaps there are wine buffs among the members (our business). In the Jerez/Sherry region of Andaluc?a, Spain, each estate has a favorite old wine called 'Palo Cortado.' Like today's orient in pearls, it is simply the finest, most elegant product of that particular producer?authentic definitions and methods long forgotten.

Personally, I'm not willing to give up on the 3-D/translucency aspect of orient, no matter how rare it might be. After all, pearlescence and iridescence are nearly synonyms, so what pearl without a degree of iridescence is even worthy of its name? Going even farther, iridescence may be the most easily faked of pearl attributes.

The term 'Orient' probably has its true origin in 'oriental pearls' (natural pearls from the Persian Gulf, India, etc), from an era in which 'water' was a quality one might likely expect to experience more than once over a career of pearling.

Purists (primarly SS/Indian Ocean region) relating to the natural era speak of a 'halo' effect, unrelated to color. Whether this is the result of light penetration of the outer layers of the pearl due to perfect alignment of the aragonite platelets, or due to diffusion of light caused by 'regular' irregularities on the surface of the pearl, the result would be the same, and equally rare.

Tahitian rainbow/peacock may fit within an updated oriental sphere, not for the colors per se, but for the 'floating' sense of those colors, creating multidimension. Problem is, it's not exceedingly rare. Quoting Strack (referring to Akoyas, but seemingly in opposition to the same author's famous denial of 'orient' in Tahitians):

Pearls page 372

"When a fine play of colour is visible just on top or just below the surface, the overtone is called orient?Orient is more characteristic for natural pearls, but it is also seen in cultured pearls of baroque shapes and irregular surfaces."

I have placed a challenge for the November 2007 harvest on Manihiki to find a cultured black pearl with orient. A premium will be paid. I am told it is possible, but that the pearl will certainly need to be preselected (in order to avoid the tumbler and destruction of surface irregularities), following its serendipitous?even clandestine?discovery.

Steve
Seattle

 

[pernula]

They are interpreting the same thing differently to suit their own industry, but at the same time using the same definition to describe the rarest and most valuable attribute found in their own production. Either way, to them, it is orient.

In Tahitian pearls it is the way the colors move around the pearl as you examine from different angles, with one color holding the center of the rings of "orient". But in white pearls and light pearls, the translucency is most certainly considered a part of orient.

It seems the way one color holding the center of the rings of "orient" and the way color move around in dark Tahitian pearls are not all that rare, so that does not seem to be in line with the stated intention of the industry to use the word "orient" to describe the "rarest and most valuable attribute found in their production." If "orient" is already present in a large number of Tahitian, then what distinguish the upper ends of Tahitianin from commercial Tahitian in terms of beauty? I am assuming factors like shape, surface blemishes, and luster are already accounted for, since these are supposed to be in commercial grading scale. I like to be educated because before I learned about and got excited about freshwater pearls in this forum, I was in the market for Tahitian and I still like them. (Might have to do my next purchase before I got into too much analysis )

There are also light color Tahitians (e.g., silver body color). Some one in the forum bought some pastel Tahitians recently wasn't it ?Sorry I don't have time to double check, lunch break is finishing up and I have to go back to work already. Do the light color Tahitians show translucency? How are their overtone and orient compared to the darker color ones?

To Ana: Thank you for the information and scientific analysis you provided. I am also into the concept of orient as iridescent with 3D/translucency, or at least into this as one of the rarest attributes of top quality pearls.

Thanks and regards to all,
pernula

 

[Valeria101]

But what is important to point out is that not all pearls will exhibit this[thin film interference]. Sure, the color expressed in the pearls above is referred to as orient. As are the colors that move around a Tahitian pearl. In the industry, we call it orient. But academically, it is not. Tahitian pearls canNOT have orient according to CIBJO and every gem lab in the world, but according to the industry they can. This is because visually you see the play of colors (the classic soap bubble or oil-slick look).

Is there an alternative explanation of whatever optical effects give the look of those pearls supposedly 'without orient'?

The debate you describe reminds me of another about 'fire' - combining the effects of dispersion, cut, color and lighting to end up with a reasonable description of a prized visual effect. Nothing terribly mysterious...

The 'fish eye' effect on dark pearls reeks of interference pattern to me. What else? Sure... the body color affects the look of the phenomenon, but this doesn't mean there is no interference trough the upper layers of the pearl, just that the sum total of whatever relevant factors (at least those lined up for 'fire' and then... pearls have a rather more complex structure to deal with etc.) yield a different look of it. At the very least would expect the body tone (i.e. absorption) to play a BIG role in what the effect o interference shows up like.

Is there any mainstream explanation of these interactions (body color - interference - nacre structure)?

 

[jshepherd]

The color that most describe in Tahitians as orient is not as rare as the true definition of the word, that is true. But it is not a common attribute in the overall sense, and is indicative of a high quality Tahitian pearl.

I think it may be best to refer to Strack on this overtone vs. orient question in relation to academia and industry.

Overtone

The iridescence of Tahitian cultured pearls always appears as an overtone which seems to float on the surface of the pearl in the shape of a circle. The overtone consists of one, two or three almost transparent colours, which stretch over the circle. They can be seen most easily if the observer looks across the shining, reflecting surface directly into the surface layers of the pearl. Orient is not found in Tahitian cultured pearls.

Both the presence and the hue of the colours depend on the size of the aragonite platelets in the upper nacre layers of the pearls, and they also depend on nacre thickness.

 

[perlas]

The term 'Orient' probably has its true origin in 'oriental pearls' (natural pearls from the Persian Gulf, India, etc), from an era in which 'water' was a quality one might likely expect to experience more than once over a career of pearling.

Checked the Strack book. The observed characterisctic of natural pearls from the Persian gulf is the outer pearl layers are transparent when viewed in at least 40x microscope.

I have placed a challenge for the November 2007 harvest on Manihiki to find a cultured black pearl with orient. A premium will be paid. I am told it is possible, but that the pearl will certainly need to be preselected (in order to avoid the tumbler and destruction of surface irregularities), following its serendipitous—even clandestine—discovery.

This is interesting. Keep us posted.

It seems the way one color holding the center of the rings of "orient" and the way color move around in dark Tahitian pearls are not all that rare, so that does not seem to be in line with the stated intention of the industry to use the word "orient" to describe the "rarest and most valuable attribute found in their production." If "orient" is already present in a large number of Tahitian, then what distinguish the upper ends of Tahitianin from commercial Tahitian in terms of beauty?

Considering the bulk of the production of Tahitians out in the market, we may even include freshwaters, akoyas, and south seas, "orient" without translucency is still rare.

Although I've seen a lot of "orient" without translucency around (however, note that I am in a pearl country), seeing a vast number of pearls out commercially, in lots, in hanks, and loose pearls show a very small percentage of pearls with a play of color.

Is there an alternative explanation of whatever optical effects give the look of those pearls supposedly 'without orient'?

I remember that high manganese content in the water make the pearls fluoresce, which is another optical effect. Even a pearl without a play of color but with a strong single-colored overtone but fluoresces is a delight and not at all common.

Not sure but fluorescence maybe be associated with the halo effect.

 

[Valeria101]

I think it may be best to refer to Strack on this overtone vs. orient question in relation to academia and industry.

The citation gives a clue...

... that the association between the physical phenomenon (thin film interference) and the visual effects known under competing trade names is not very consistent. Apparently, it is OK to explain the iridescence in light color pearls (='orient' traditionally via interference, but then it is not OK to call 'orient' the visual effects due to the same physical phenomenon in other types of pearls.

On a hunch, it sounds only normal that on a lighter background the full spectrum of diffraction is seen, while on a dark background only some colors appear in circular 'layers' with the prevailing color changing with the angle of tangence relative to the line of sight.

I would definitely expect such subtle colors to be more visible on dark pearls - just like they are so much more vivid on dark opal base than light (treating matrix opal makes a striking experimental example - for just how much visual impact changing the base color only has). The artificial darkening of the base color of iridescence happens to pearls too, only I have never heard of the same reasoning applied to pearls in any way. Here goes:

How about a simple experiment you must have observed already: how does the appearance of 'orient' change when the color of the nacre is altered by dieing? Clearly, there could be many explanations why pearls with classic 'orient' do not acquire the 'fish eye' pattern once died. But if some do.. it would be a relevant example for the hunch above, I would think.

And another: if the different type of iridescence on black pearls is due to the structure of nacre more than body color, how about the light color pearls coming from the same Pinctada species (and arguably with similar structure): do they have the 'fish eye' or the 'orient' type of iridescence?

Hope these questions are not boring everyone to death... Obviously, they are just delightful theory to me (i.e. things I would crave to read about in gemology journals but have not found them yet ). Got to get Strack... if only for this bit.

 

[perlas]

An off-shoot thought to Valeria's post.

The dyed black fwps with peacock colors..... afterall, the pearls may have just been maintaining their orient (with connection to thin film interference) but just more visible due to dye. Thus, why can't tahitians have orient? I think orient is not related to body color.

I don't think any other artificial treatments are being applied to produce the wild, play of colors in dyed pearls.

I have to agree with Valeria... I just remembered how harder it is to find orient in white south sea pearls....

 

[SteveM]

The modern-day concept of a relationship between the inherent prismatic properties of nacre's aragonite platelets and 'orient' seems here to stay. But it seems a distinct lowering of standards from an historic point of view (a century-long process, of which I can claim only the past few months as witness!). Perhaps the pearling world would be better served to break free of the gemstone-dominated regulatory bodies and their respective masters?cut stones holding the distinct advantage prismatically, not to mention commercially. Regarding South Sea pearls?the nearest modern descendants of the original 'oriental' pearls?here is the somewhat infamous text from Paspaley's website, which adamantly omits mention of color:

"Lustre and Orient are the words [used] to describe the appearance of light reflecting from deep within the perfect layers of fine quality pearl nacre?

"When natural pearls reigned supreme as the queen of all natural gems, fine quality natural South Sea pearls were prized above all others due to a characteristic known as 'Orient'. Orient is only found in pearls from 'seawater' pearl oysters, and orient only 'appears' with a perfect combination of nacre thickness and nacre quality."

For what it is worth.

Steve
Seattle

 

[Valeria101]

Skimming thought the thread, there are a couple of places where translucency and iridescence (using this word for now, to keep away from 'orient') are implied to be disjoint: i.e. iridescence can happen w/o translucency, and the other way around. The 'other way around' seems straightforward - a sort of dull pearl.

But... if iridescence comes from interference, the nacre has to be translucent in order to let light get though some of the outer layers.

What gives? Is it a matter of degree you are talking about? (i.e. enough translucency to see it as an independent phenomenon)

And, what would be an example of pearl with strong iridescence and no translucency to talk about? My mind draws a blank on that one ...