Color treatments of China origin pearls are for the most part aimed at the creation of fantasy colors that could never occur naturally. We could seldom find evidence of successful color treatments aimed at colors in the typical range. White pearls of any type must be assumed to be bleached, but this is rarely disclosed. Freshwater pearls have or fade to whiter colors than do ocean-cultivated pearls, but the proportion of white pearls on the market is much larger and whiter than what could occur naturally.
Processing, including color treatments, of China freshwater pearls evolved rapidly because so many dealers had lots of pearls nobody wanted. The very low value of much of the candidate material allows color processing to be sold as a service, and encourages experiments that would never be considered in treating costly ocean pearls. The latter are only assembled to strands after processing is complete, but in China it is still common to see hanks of strands in bleach bottles, and hanks of dyed or bleached pearls with discolored or disintegrating threads. The most difficult part of bleaching, ie rinsing out the peroxide, is sometimes omitted. That leads to rapid loss of luster, but who cares?
We choose those combinations of shape, surface and fantasy color that produce an attractive look not available naturally. An example are rosebud and other textured-surface pearls, which look especially good with bronzy or goldy dyes. Blue-black or peacock dyes also produce some knockout fantasy colors. Greyish colors of any depth also require color treatment, as freshwater typical colors include only a few very pale bluish tones. They are on the other hand the most common colors of non-nucleated ocean pearl cultivation by-products, ie ocean keshi pearls. Since the latter generally command a much higher price, it is popular to approximate the look by selecting certain shapes of non-nucleated freshwater pearls and dyeing them grey. With the improvement of grey dyes available in China, it has become unnecessary to import these to Japan in order to make them grey using Cobalt 60-gamma irradiation, as it was in the days when the grey dye used in Hong Kong was unstable and grey dyed pearls tended to become spotty. This type of irradiation affects freshwater pearl nacre; the reason it works on ocean cultured pearls is because the nucleus is freshwater shell, and the nacre coating thin enough for the color to show through. As of early 2011, cobalt irradiation with a choice of duration is available in China; it is difficult to determine which grey pearls are dyed, irradiated or both.
Customers whose markets demand all-natural products will be informed about all pearl treatments of which we are aware or which we consider likely. We give preference to suppliers who are knowledgeable and frank, and invest our efforts in knowing what we buy. We believe this is more helpful than merely repeating suppliers' claims, or limiting our stock to pearls that are unlikely to have been treated in any way. For a discussion of color treatments of ocean pearls, please see akoya pearl color treatments.