Is that photo distortion, or are the front pearls actually a bit egg shaped?
The off-round shape comes from the freshwater pearl being all-nacre, without a bead inside (just a little piece of mantle tissue). Not having a bead, they are very durable even for everyday wear, which is not generally recommended for akoya pearls.
However if they are freshwaters, they are not antique. These nearly-round freshwater pearls have not been produced that long.
If they aren't off-round at all, then you may have some akoyas. Freshwaters are now also sometimes being bead-nucleated but I think that's mostly in the larger sizes.