Size is the only advantage of SS.... and you have to trade in quality for size for all but a rarefied elite. I've got my fair share of blank stares when telling folks that SS pearls are 'not good enough' (roughly). But again, it isn't common to see the different qualities of SS let alone large, fine freshwater all in one place to get that bit of experience and I didn't have a bag of samples to show... better not say anything at all

Very nice freshwater pearls may be there around 13mm. Whether any such large ones would be good enough to get the 'Freshadama' label, no idea. I have never seen a non-graduated strand of round freshwater that large that were not nucleated. Zeide here, appears to have seen everything and know everything about freshwater pearls! Including where to get them

Among the south sea, south sea keshi would be my favorite - they appear to have the glow of natural pearls like the 'Freshadama' does, but with a different personality (they look 'cold' to me, if that makes any sense).

You may find a related chat on the thread about the 17mm south sea pearl. I would expect to find the better quality south sea pearls at most 15mm large (with wishful thinking). Not that larger are not there, just barely. Low quality ones make a good match to shell pearls - as if they had overstretched skin...