Hi
We love to figure out what we can when it comes to natural pearls. Now first, what kind of natural pearls are they supposed to be? Where would they have been from? They don't really look like Persian Gulf or Bahraini pearls and those are both the proper names for "Basra pearls". Basra pearls is a term used by ebay sellers- I have never heard it anywhere else.
I am not denying what you say, but let's get really careful and precise. A lot of people think real pearls are natural only. Real pearls can be either natural or cultured, so we need to clear up the meaning of that expression. it is just that most people really do not know pearl terms and tell their grand-kids the wrong story.
First, you need more and better pictures with close ups of some of the pearls like the one right in the center that has a dent or something similar. Please tell us the actual story, like how old your gt grandmother was and about when did she get the pearls about what year or decade. What size are they are what kind of findings or clasp does it have. Without actual equipment, we need excellent visuals to guide our attempts to tell you just what those pearls are.
So far, they do not look at all like natural pinctada radiatas, the actual species Persian Gulf pearls come from, but with more photos and info, we may be able to tell you more than that.