[Casey.R]

I've been comparing the orient on some of my pearls. One of my favorites are the untreated freshwaters I bought from PP during the mothers day special.They have teal colored orient and some pink orient which looks great with the pinkish lavender body of the pearls. My other favorites are some keishis I bought from wats2luv on Ebay. They also have really strong orient too. It's sort of blue rose and green on a cream colored body ( I wonder if they are unbleached?).

Anyway I just bought a strand of the white baroques from PP. First I have to say they are very pretty and a perfect addition to my pearl wardrobe. I really wanted large white baroques since they go with everything, and I had two put on french wires so I could also have earrings . But I have noticed they don't have the same type of orient as the pearls I mentioned above do. Mostly I see pink, but it's not super strong.Could this be from the bleach? Or do certain colors just show secondary colors better than others?

[perlas]

Hi Casey,

You must be confusing overtone with orient. There was a discussion here about the difference between orient and overtone.

overtone versus orient

[Perle]

You might find this article on “orient” interesting (I think it's been cited elsewhere on the forum):

http://www.opticsexpress.org/DirectP...TOKEN=95789648

But I think you might be referring to “overtone.” I believe Strack says that (natural, not chemical) overtone depends on nacre thickness and the size and arrangement of the aragonite platelets.

There are some discussions of bleaching on the forum, but I think in this case what you are seeing probably is more dependent on the pearl's structure, shape and bodycolor. The reason I say this is because certain types of pearls generally have more pronounced and varied plays of color than others (even if unbleached). But perhaps the experts can chime in on this!

Perle

[Casey.R]

I don't know maybe I am. I'll read it. I'm talking about the color that moves when you move the pearl around which I have always thought was orient. The soap bubble type colors.
If it depended on thickness than all freshwater pearls would have great orient right? But they don't all have it so it couldn't be that alone. Anyway I'll have a look at the links you posted.
Thanks!

[Casey.R]

I've been examining them again.
Now I think the reason the orient isn't intense on the new white baroques is because there isn't any. I think the subtle color is overtone. I am positive it's orient on the other two though.

On my tahitian pendant and earrings I get a few colors at once. What I see is a gray colored body with a rose overtone and teal which looks kind of like a halo and I believe is the orient.

[Perle]

You might find this helpful (on pg. 556 of Strack's book, emphasis added, in the section discussing Tahitian cultured pearls):

“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 colors, 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.”

Perle

[jshepherd]

I agree. You are probably seeing overtone in the pearls, not orient. A slight pink coloration on the surface would be the overtone, but the deeper translucent colors would be orient.

[Casey.R]

Well I don't know what people are calling it ( this post has only made it more confusing to me ) but it's colorful and pretty. So you think bleach is killing the extra color?

[Casey.R]

Originally Posted by jshepherd

I agree. You are probably seeing overtone in the pearls, not orient. A slight pink coloration on the surface would be the overtone, but the deeper translucent colors would be orient.

which pearls?
can someone post some photos as examples ?

[Casey.R]

I was looking at the perlas site which has some information on optical qualities of a pearl.
See, to me the photo that is showing orient looks like what is being desribed as overtone on some other sites. I've always thought of that type of color as orient ( well since I first heard it described anyway) It's really very confusing to me. :-/
Oh well.
Nice pearl in the photo by the way.
http://www.perlas.com.mx/english/orient.html

[jshepherd]

No, bleach does not affect the orient. Some pearls have it, some do not. Most pearls do not as orient is considered an extremely rare value factor. It is more prevalent in colored pearls and in baroques, very rare in white. The job of the bleach is to change the original color of cream/yellow to white, and to make the pearls match throughout a strand.

Orient is very difficult to capture on film. Occasionally we are able to catch it just right, but it is difficult.

To make matters even more difficult, many experts do not agree on the definition of orient. To some it is simply the play of color over the surface of the pearl, to others it is thin film interference, to others still it is the light diffraction passing the the conchiolin translucence of the linear layers of nacre. According to CIBJO, orient is an optical phenomenon caused by the interference AND diffraction of light from within the surface of some nacreous pearls; produciong delicate shades of iridescent colors.

This is why Strack says there is no orient on Tahitian pearls, although the majority opinion would differ from hers. Even Paspaley has their own (albeit unique) definition of orient. Their definition excludes all pearls that are not of marine origin from possessing orient - freshadama do not exist.

I do not think you should feel at all bad about being confused by orient. As you can see, most of the world is!

[smetzler]

In the Cook Islands, the definition of orient is the effect known here at Pearl-Guide and elsewhere as 'water' (translucence of the outer layers), iridescence being related more directly to the overtones.

Steve
Seattle

[jshepherd]

One thing is important to point out. Every pearl producing region (more or less) claims a definition of orient that suits their pearls. They very often disagree with any other definition. It really does create a lot of confusion. It may be best to just accept one "pearl's" definition within its own market.

[smetzler]

That makes sense and is a perfect reflection of human nature, but I'm thinking of the range of colors and peacock tail effect obtained on Manihiki and wonder if the more universally accepted definition of orient would not be advantageous to them ('orient' being considered a rarity to the degree of legend status).

Steve
Seattle

[Perle]

Interesting discussion!

Here's another, somewhat more recent article:

http://www.opticsexpress.org/DirectP...TOKEN=95789648

which attributes iridescence (equated in the article with “orient”) to diffraction and interference (both), which, technically, makes sense in that case (interference also is going to affect the visible colors).

I'll write out the CIBJO definitions for orient and overtone for others following this thread:

Orient: an optical phenomenon caused by the interference and diffraction of light from within the surface of some nacreous pearls; producing delicate shades of iridescent colours.

Overtone: the presence of an additional colour on a pearl or pearl product, usually pink, gold, green, or blue.

Strack says that “[o]rient is usually attributed to a combination of two effects: interference of light on the layered structure of the upper part of a pearl and diffraction of light on the linear relief structure of the surface” (p. 289).

So Strack takes the CIBJO view, but the majority does not – why? If I were to take a guess, I'd say that both are normally present, but often one more than the other, and that diffraction tends to produce the rainbow effect, whereas interference tends to produce the overtone (or multiple overtone) effect, and, although both can result in “iridescence,” Strack considers only the former to be “orient,” whereas the majority considers the latter to be “orient” also?

Perle