In 1996, I went thru a terrible divorce.
Thru my healing of I met a Lakota medicine man.We became fast friends and one day he told me of a treasure in Texas few are aware of and in my 40yrs as a Texan had never heard of-Texas freshwater pearls.
My first try and i found a 3mm metallic blue pearl,one of the rarest of the pearls.
I was hooked and my trilogy of pearling began.I lived on the Brazos river for 6 months moving up and down it seeing wildlife of every sort imaginable even ostrich gone wild...
They say the freshwater mussels do not make black pearls(in Texas) and I found a three colored 13x 11 mm blister pearl that is black, lavender and amber colored. I carefully cut it out of the shell and had it filled as it is hollow and am currently pondering a setting for it to give to my wife.
Thru the years of hunting the tampico pearly mussel I have found the reason for the making of pearls. I also found they imbed the pearls into their shell and that they can re-soften their shell to imbed the pearls. They make the lustrous pearls for the inner shell and the brown/tan pearls for the outer shell. The blister pearls are made by them putting decaying river material between the shell and the pressure of the methane gas, blows a bubble which we call "blister".
I could go on awhile of my studies and will have my partner upload some pics of my findings.
To me mussels are a most fascinating creature.
I even trick them out of their pearls so as to not have to destroy them :).