Hey there! It is hard to tell from your pictures. Would you please set your camera on macro setting (flower sign) and then take some close-ups on white background in indirect light? Thanks.
You can check of they are fake by gently rubbing one against your teeth. If it feels gritty it is not fake.
My thought is too that it looks like akoya pearls. Akoya pearls are genuine pearls that are cultured, so they grew in an oyster but around a bead that was planted there for the purpose.
The first thing I thought of was the "add-a-pearl" necklace. But they might have been purchased to be kept in reserve in case a necklace needed repairs. An add a pearl necklace would have had a fine chain to which the pearls were added on each birthday or special occasion. In that case, the drill holes would be larger than usual.
Of course, when I see three pearls, I think of making earrings and a pendant.