Sorry to say but they really look like imitation pearls to me.
They are extremely uniform in shape, size and color, and very shiny. The clasp looks like the sort one sees on imitation strands.
Listen, I got married wearing imitation pearls. If these are sentimental to you (and it seems they are) there is no reason you can't wear them! It would not be hard to restring them yourself, either. We have tutorials for that on the Lowly Beaders Club.
But if you really want to wear genuine pearls, those can also be bought for not a lot of money now that freshwater pearls from China are so very nearly round.