The white pearls are cultured freshwater pearls from China.
The black pearls appear to be imitation.
There is a simple test you can do with the black pearls: Rub 2 of them together. Imitation pearls glide smoothly while real pearls feel a bit gritty. Edited to add: I have stopped recommending rubbing pearls against teeth to test them. Teeth are harder than pearls and can scratch them.