Near round/Off round Akoya pearls or freshwater pearls?

[Classicpearl]

Hello. I am considering these pearls. I am looking at the more yellowish triple strand. The local store selling them said they are vintage and “near round” or “off round” akoya pearls. Is there any way to tell if these are indeed near round akoyas or if they are just freshwater pearls? The largest pearl on each strand towards the center is a bit more oval/potato shaped, although none of them are perfectly round. What is the likelihood or rarity of near round akoyas from back in the day versus round akoyas or off round freshwaters? Could there be a higher percentage back then than today?

Also, the clasp has pearls and sapphires but the pearls on the clasp are considerably whiter and more perfectly round compared to the rest of the strand, could this mean the clasp was added later on?

Any help or advice would be greatly appreciated!