There are very few actual pearl farms there but thousands of people willing to sell you Chinese freshwater as fake Vietnamese akoya, unfortunately.
There is a Japanese pearl farmer that operates a farm in Vietnam. His family company is called Spica. They sell wholesale but have limited production. Their pearls have super-thick nacre too.
it's amazing how quickly people have jumped on the Vietnamese Akoya bandwagon; I would have thought these little treasures would stay under radar for at least a few years...
Jeremy do not forget Orient Pearl who has around 4 farms there, they are big in the smaller sizes starting from 1.8mm to 5 mm and you are right, the nacre is much thicker than most Japanese Akoya pearls. The color is mostly cream but the luster is very high. I have some Vietnamese South Sea pearls also but the oysters died because of unknown reasons