>  I just received a catalog with what they list as natural fresh water  pearls.
>  I know the white, pinkish and purplish are natural. But they have  copper,
>  black and blue are these natural colors and if so what shells are they  from?

All freshwater pearls come from unionoid bivalves.  Major producers are China, with Hyriopsis cumingii as one of the main species used, and Japan, with Nodularia douglasiae as a major species used.  Some species vary in the color of the nacre; others are fairly consistent.  It's a large enough industry that a relatively rare color form (in percentage) can still get onto the market.

    Dr. David Campbell
    Old Seashells
    University of Alabama
    Biodiversity & Systematics
    Dept. Biological Sciences
    Box 870345
    Tuscaloosa, AL  35487-0345 USA
    [log in to unmask]

That is Uncle Joe, taken in the masonic regalia of a Grand Exalted Periwinkle of the Mystic Order of Whelks-P.G. Wodehouse, Romance at Droitgate Spa

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