There is no doubt these are natural color Mississippi River pearls. I have original letters written in the 1920's from a pearl dealer selling all sorts of colors. He sold all over the world mostly went to a major retailer in London and Paris. I am short on time to write more but he wa the major dealer selling to Mossarieff (sp) descendants still in business. If you would like to see a copy of some letters let me know.
Personally I have traveled the Rive since 1965 and have a fishing cottage there now. Once people travel 25 miles away they have no knowledge of the river system that drains 2/3 of the continental US. Bye for know God Bless
Not these...these pearls have very tight nacre structure and I can't see any "protein deposits" or "darks spots" anywhere...my guess the colors are 100% due to optical characteristics of their nacre: pure Orient