They appear to be imitation pearls. The uniformity of shape, size, color and lack of luster all point to it. The fact that they are not knotted between pearls and the small pearl on each end of the strand are also not unusual with imitation pearls. The clasp and the way the pearls are finished next to the clasp are also low end.
Wipe them clean with a soft, damp cloth and gently rub one of the pearls against another. Imitation pearls glide smoothy against one another, while real pearls feel gritty. If the pearls have a patina of grime they may feel sticky, but not gritty.