Pearl treatments

[TSH]

Hi,
I have some questions regarding pearl treatments.
-Is it true that all pearls exported to the USA need to be treated?
-What are the acceptable forms/types of cleaning and treatment of pearls?
-What are the forms/types of cleaning and treatment that would be frowned upon?
-What are the the forms/types of cleaning that would increase the value of pearls?
-What are the forms/types of cleaning that would decrease the value of pearls?

Much thanks to anyone who can give me information regarding these questions.
If it helps, I am referring to the treatment of Chinese Akoyas.

 

[jshepherd]

All Akoya pearls from both Japan and China are treated before coming to the US. In fact, the pearls are kept in distilled water prior to treatment so they do not dry out.
Acceptable forms of treatment are bleaching, pinking, and polishing. Other treatments, such as heat treatments and coatings of any kind are frowned upon.
Polishing, heat treatment (on lower-luster pearls), pinking etc., all increase the market value of the pearls. The only treatment that would decrease the value is a color treatment such as to create black Akoya or yellow.

 

[Meech]

Hi,

Is there a way to determine (with the naked eye) whether a pearl has been heat treated or coated?

Thanks,

Meech

 

[jshepherd]

Yellow is not a color the farmer likes to see in his pearls. Cream is ok, but to an extent. When the cream reaches the saturation to have a slight yellow coloration, the pearls have to be color treated. At the same time, if the pearls have a brilliant yellow/gold coloration they are sold as such, natural color. These can actually be expensive. Imperial carries a line of these, and they are sold at a premium.

Not all factories approach the color treatments the same way. Most factories that I know of bleach and then pink the creamy to yellow pearls. If the process does not work (it will invariably not work on all), the pearls are sold at a discount. Other factories will dye the pearls either black (when I say black I mean all dark colors like bronze, green, etc), or dye them gold.

When I am making a large purchase, I always take some of the creamier pearls with superb luster. Not a lot, maybe only 2-300 strands of a given size. This is simply because there is a market for them, and we do get calls looking for that color. But, by far we buy more with a rose or silver overtone.

 

[TSH]

A question still

A question still

Lots of good information in this thread. Thanks.

Going back to one of my original questions:
Do all pearls exported to the US NEED to be treated or are they just treated by default? The operative word in my question is need.

Thanks again.

 

[you hongqing]

all the akoya pearls should be treated

all the akoya pearls should be treated

Hi,
All the akoya pearls should be treated. No akoya pearls should last their luster and color for long time without treatment. Good treatment, thick nacre, and good luster keep the akoya lustrous and attractive. So far, cold treatment is the best way to bleach and dye the akoyas. Heat treatment could destroy the character of the akoyas. These akoyas will loose their luster and color in the coming monthes.

Light yellow pearls commonly dyed black. The golden yellow akoya peals can directly be strung to strands without bleaching. These pearls are rare and not so many for the market.

 

[you hongqing]

Hi,

Is there a way to determine (with the naked eye) whether a pearl has been heat treated or coated?

Thanks,

Meech

The freshwater pearls can be heat treated and then cold treated. The akoya pearls can only cold treated. If not, all the akoya pearls would be cracked.

Best regards,

You hongqing

 

[perlas]

Anyone know how cold treatment is done?

I understand that heat treatment lightens the pearls, but how does cold treatment improve the pearls?

 

[TSH]

Reply

Reply

I think my question is answered. Sounds like it is not a requirement for pearls to be treated but it would generally not be a good idea for aesthetic reasons if they were not, and therefore should be treated.
Correct me if I am wrong.
Thanks.

 

[youngster]

This has been fascinating and I've learned lots. This thread and the one on overtone vs. orient has me curious about the treatments freshadamas go through. My understanding is that freshadamas are subject to limited treatment (like light polishing). Jeremy, feel free to chime in on this!

 

[Zeide Erskine]

Hi Caitlin,

The main choices are clear mineral oil, cotton seed oil, and corn oil. Corn oil would add a touch of cream to the color while the other two a colorless. However, my freshadamas were a touch on the creamy side, so it may well have been corn oil.

Zeide

 

[lisa c]

Hi Caitlin,

The main choices are clear mineral oil, cotton seed oil, and corn oil. Corn oil would add a touch of cream to the color while the other two a colorless. However, my freshadamas were a touch on the creamy side, so it may well have been corn oil.

Zeide

Hi all,
Is this another instance of Z misinformation? Sigh. Probably.

 

[Caitlin]

weeeelllllll... it isn't quite that easy.
Sea of Cortez uses a dip of mineral oil to clean newly harvested pearls and says a dip into mineral oil can restore old pearls, but not to use it more than once in years. I'm vague on that, but repeated dips are not good.

I think Jeremy has used corn oil on freshwaters on occasion, but I can't remember what occasions......

I'd say skip the cottonseed oil until another expert recommends it.