No, pearl color is not totally dependent upon specific region, but are from other factors such as the color of the mollusk’s mantle, the donor mantle tissue from another animal, trace elements in the water and a few other reasons. Region would come to play a very minor role in terms of the mollusk’s environment and food sources (those trace elements at work), but it is not a dominant factor in determining color. A single freshwater pearl mussel can produce up to 50 pearls per single animal, and you’ll find a variety of Pink, Peach, Apricot, Lavender and White colors all nestled inside the same shell! Pretty incredible, yeah?
I’m attaching a picture of the Hyriopsis cumingii hybrid Chinese freshwater pearl mussel, freshly opened at harvest so you can see for yourself the rainbow of colors these mollusks produce. Colors are 100% natural with no treatments, and will never fade or discolor over time.
Freshwater pearls from the H. cumingii pearl mussel – check out all those colors!! Image courtesy of pictify dot com
Pearl color is still not a fully understood phenomenon, but scientists all over the world are working to solve this mystery. I recently explored how Tahitian pearls get their colors in this blog post: http://www.purepearls.com/blog/2015/02/what-gives-tahitian-pearls-their-black-colors/ It gets a bit nerdy lol, but I think I did an OK job of explaining the basic mechanics of how various colors come to be for the pearls. The same principles apply for Freshwater pearls, so I highly encourage you to give it a read – it’s not long.
I hope this answers your questions, and that you like the blog post –especially if you’re interested in the nitty gritty of pearl science.