I agree, ringed freshwaters. It is difficult to explain. The colors lay differently on Tahitians. One seldom sees bright green and bright blue on the same pearl. Strong blue is rare in 1 Tahitian pearl, even more rare to have a strand with many blues. Shapes are off, as A Breaker mentioned.
Having a whole strand like this makes it easier to id than a single pearl, imo. Fun and wearable pearls!
@Tfragaud, welcome to the forum and keep asking questions!