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.

Hi Jeremy,

Yellow is actually a natural color for akoyas up to 50% saturation. It is more prevalent in Japan where quite a bit of pinctada maculata has entered the pinctada martensii breeding stock and rare but not unheard of in pinctada chemnitzii (the Chinese akoya scallop). Light yellow akoyas are typically bleached white or dyed very golden. The medium saturation is considered a fancy color and can command quite good prices even in excess of pinked whites owing to its natural color origin.

Picture of hamaage (untreated akoyas at harvest: http://www.kato1970.co.jp/KINDHP/pea...e/hamaage3.jpg
and http://www.pck.gr.jp/e/making/images/5-1.gif)

However, pinctada martensii does not produce white or pink pearls except in albinos that have been crowded out of the current Japanese breeding stock but still occur to a very minor extent in pinctada chemnitzii and relatively frequently in pinctada shimitzuensis.

Zeide

Hi,

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

Thanks,

Meech

Hi,

That depends on how many pearls you have seen in your life. I can see coating, but not everybody seems to be able to see it at first glance. I recently went to a department store here in California (Gottschalks) and all their pearls looked coated. I asked to see a strand of 8-8.5mm well rounded pink freshwater pearls and they were so heavily coated that they failed the tooth test and actually felt warm and smooth like polished plastic. In contrast, heat-treated akoya nacre feels very dry and brittle.

Zeide

Originally Posted by Zeide Erskine

Hi Jeremy,

Yellow is actually a natural color for akoyas up to 50% saturation. It is more prevalent in Japan where quite a bit of pinctada maculata has entered the pinctada martensii breeding stock and rare but not unheard of in pinctada chemnitzii (the Chinese akoya scallop).

Zeide

Zeide, why do we not see these yellow akoya marketed more commonly? Is it because the color is not distinct enough so they are bleached white or dyed? Is there a market for the 50% saturation akoya?

[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.

Hi Andrew,

There is a great and lively market for them. Collectors pay the factories about 2x the corresponding price of whites or more (depending on quality and size) for them and thus they rarely enter the wholesale market. The next lower intensity level is typically dyed a screeching metallic golden color and still fetches quite good prices and the light colors are either bleached and then pinked to a cream rosé tone or dyed a greenish black.

Zeide

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.

Hi,

Let's put it mildly, the U.S. is getting the pearls at the prices it demands. Given current culturing practices particularly in the akoya segment, hamaage (raw pearls) is ugly. Most of the times it is stunningly ugly. The few good pieces that can be used in untreated form are separated out at harvest and sold to the "connoisseurs market" (the silver ones mostly to Europe and the golden ones to South America) at 10 times of what American consumers are willing to pay and that means 10x of Mikimoto prices, not 10 times Pearl Paradise prices. These mostly involve non-white pearls since you may already have seen above, akoya hamaage does not come in white or rosé.

As the U.S. market in general favors white rosé pearls and akoyas at that, they have to be treated. Does that answer your question?

Zeide

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.

Originally Posted by Meech

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

Anyone know how cold treatment is done?

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

Hi Sam,

Cold treatment refers to chemical bleaching and dying without heating. Actually, it means bleaching without dry heating because even in so-called "cold treatment" the pearls are kept for a period of 6 weeks to three months in a hydrogen peroxide solution under intense (warm) light. Heat treatment involves drying the pearls afterwards in heating cabinets for another few days at temperatures of up to 80°C which leaves the nacre brilliant but brittle. This method is routinely used on short-cultured akoyas both in Japan and in China. It is not used on freshwater pearls because they retain more conchiolin even after bleaching that would turn brown under heat treatment.

Zeide

Zeide,

I know the the pearls are soaked in bottles of hydrogen peroxide solution for months and then polished. I did not know that this is called cold treatment. And here I am imagining freezers and nitrogen and stuffs .

Thanks for the tidbit.