Growing pearls relies on a tiny (usually) around 1mm sliver of donor mantle growing into a maybe 10mm circumference balloon around a nucleus. It's remarkable that it happens without great incident as much as it does.
Incidentally, why such a small piece? Has anyone experimented with bigger? Is 1mm just 'done because that's just how it's done and always was done?
Douglas, thank you for your response - very interesting. It seems to me that there is a lot of discussion about pearl blemishes but not much understanding as to the underlying causes. I think it is something that consumers could be better informed about. It could aid in an appreciation of pearls along the entire spectrum of surface quality, from blemished to flawless.
There isn't much understanding CMN because a lot of the time we simply don't know. It's the same with pearl colour. Why do pearls have colour at all? It's dark where they live usually, they don't need to look fancy to pull a hot mate.
Pearl in latin is margarita. From which we get Margaritifera margaritifera I am a margaritifera - a seller of pearls.
Unionidae are the general family of bi-valve freshwater mussels
Unless the people on the island spoke latin, I think possibly not
The Romans referred to pearls by the Greek name margarita, and differentiated between various kinds. The largest and most beautiful were called unios; pear-shaped pearls were called elenchi; and when clustered together so that they gently jingled with movement—attracting attention with the noise—they were called crotalia, or castanets.