Well, at first sight they seem to be Potatoe freshwater pearls from China...but they could also be natural baroque pearls.
Did she leave any information about the pearls? Source/origin?
Since the pearls belonged to an Australian couple and are from some time ago, and antique dealers...there is a chance those are actually natural pearls.
It is it's whole inner structure.
Then, I also saw the other pearls you have...they all look like freshwater pearls.
You should take the "Pearls as One" pearl course.
Not really. Everyone can do it...you just need some training. That's all!
But the original photos you sent made me "see" something different. Once I saw the actual broken pearl: it was a complete giveaway.